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Qt for Symbian
Ltd.P. Fitzek Tony Torp Tommi Mikkonen A John Wiley and Sons.Qt for Symbian Edited by: Frank H. Publication .
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3.1 Symbian – The Technology 1.2 Java 2.1 A Cross-platform Development Environment 1.2.3 Perl 1.1. Janus Heide.2 Symbian – Evolution to the Leading Smart-Phone Platform 1. Fitzek.CONTENTS Contributors Foreword Preface Abbreviations Acknowledgments Publisher's Acknowledgments About the Editors 1 Introduction and Motivation Frank H.1 Ovi Suite 2.2.3 Symbian – Casual Application Developer 1.1.2 xi xiii xv xvii xix xx xxi 1 1 4 5 5 6 7 7 7 10 11 13 13 14 14 15 .P.P.3.3 Qt 1. Tony Torp and Tommi Mikkonen The Importance of Mobile Developers Symbian OS 1. Pedersen.2.1. Frank H.1 Installing the Development Environment 2.3 Qt Licensing Bibliography 2 Getting Started Morten V. Fitzek and Tony Torp 2.2 Qt in the Mobile Domain 1.1 1.3.
5 Open C/C++ Plug-in 2.1 Building 126.96.36.199.5 User Interface 3.4.3 Implementing Slots and Emitting Signals 3.4.2 Packaging 3.1 QObject 3.3 Signals and Slots 3.5. Fitzek 4.P.4.5.5 Connecting Signals and Slots 3.3 Widgets.2 Parameters 3.1 Creating a Network Session 3.2 Introduction Bearer Management 4.1 Input/Output 3.1.6 The Carbide.3.2 Files and Streams 3.3 2.7 Qt for Symbian Using Carbide.4 Qt Object Model 3.1 Basic Signals 3.2 Timers and Painting 3.7 Communication 3.2 2.4 Meta-object Compiler (moc) 126.96.36.199.6.3. Tony Torp and Frank H.2.c++ with Qt for Symbian Summary 15 17 19 20 21 26 29 29 30 31 32 32 34 35 35 36 37 37 38 39 39 40 42 42 42 43 45 47 48 49 51 52 52 56 64 65 65 66 67 3 Qt in General Andreas Jakl Hello World 3.2 Custom Signals and Slots 18.104.22.168 Networking and XML Bibliography 4 Qt Mobility APIs Tommi Mikkonen.1 Events 220.127.116.11 Basics 3.c++ IDE 2.2 Object Ownership and Memory Management 3.2 Internationalization 3.4.6 System 3.4 Symbian Platform SDK 2.6 Properties and Meta-information 3.1 Handling Text through Implicit Sharing 3.7.1 4.1.1 Layouts 220.127.116.11 . Dialogs and the Main Window 3.vi Contents 2.
3 Utilizing Platform Features beyond Qt APIs How to Use the Mobile Extensions in Your Project Alarms 5.7 .2 Using the Viewfinder Widget 5.1 Creating a New Contact 4.2 Creating a Workday Wakeup Alarm 5.3 4.2 Finding a Single Contact Detail 4.2 Accessing System Information 184.108.40.206 Messaging 4.2 Getting a List of All Landmarks in the Landmark Database 67 68 68 68 69 69 70 71 71 72 72 72 72 73 73 74 74 75 76 77 77 78 78 79 79 79 80 80 81 81 82 82 83 83 84 84 84 85 85 86 86 5.5.4 Deleting an Alarm Calendar 5.1 Getting a List of All Alarms 5.3 Editing a Contact Detail 4.10 System Information 4.1 Creating a Landmark for the Current Location 5.5.3 Changing the Time of a Specific Alarm 5.P.7.10.1 Playing an Audio File 4.10.1 Creating a New Calendar Item 5.2 Uninstalling an Application in the Background without Notifying the User 5.4.5 5.7 Multimedia 4.1 Camera Initialization 188.8.131.52 Summary Bibliography 5 Qt-Like Mobile Extensions Tony Torp and Frank H.3 Taking a Photo Installer 5.9 Service Framework 4.1 Creating and Sending an Email Message 4.6 5.2 Deleting Calendar Entries Camera 188.8.131.52 Getting and Following the User's Location 4. Fitzek 18.104.22.168 Accessing Device Information 4.2 5.6.5 Location 4.4 5.3.7.Contents vii 18.104.22.168 Getting a List of all Installed Applications in the Device Landmarks 5.4 Contacts The Contacts API 4.1 22.214.171.124 Publish and Subscribe 4.4.2 Creating a Playlist of Videos and Playing Them in a Video Widget 4.1 Installing an Application in the Background without Notifying the User 5.5.
12 Vibra 5.3 Setting the Ringing Volume of the General Profile to Maximum 5.2 Memory Management 6.1 Displaying Messaging Accounts 6.1.1 Descriptors 6.3 Executable Files 6.11.viii Contents Profile 5.8.1 Combining Qt and Native C++ 6.11 Utils 5.5 Active Objects 6.10. Pedersen and Hassan Charaf 18.104.22.168.2.8.7 Threads 6.1 5. Kyller Costa Gorgônio and Hyggo Oliveira de Almeida Data Types and Symbian OS Class Naming Conventions 6.10 Telephony 5.9 Summary Bibliography 7 Qt for Symbian Examples Bertalan Forstner.3 Two-Phase Construction 6.8.1 Making a Circuit-Switched Telephone Call 5.9.4 Other Issues 6.2 The Cleanup Stack 6.8 87 87 87 88 88 88 90 90 90 91 91 92 92 92 92 95 95 96 98 98 98 99 100 100 101 102 103 105 105 105 105 106 107 115 116 116 117 117 117 .3 Converting between QString and HBufC* 5.2 Arrays 6.2 Launching a File with the Default Viewer Application 5.1 Switching on the Vibration Function 6 Qt Apps and Native Symbian Extensions Angelo Perkusich.9 Sensors 5.8.1 Getting the Current Active Profile 5.1 Leaves and Exception Handling 184.108.40.206.1 Keeping the Device Backlight Turned On 220.127.116.11 Qt for Symbian 6. Imre Kelényi. Morten V.11.2 Receiving Notification of When Phone Call Status Changes 5.6 Error Handling 6.2 Building Qt Applications in the Symbian Environment 6.1 Mobility API Examples 7. András Berke.2 Setting the Current Profile to Silent 5.3 Separating Qt and Symbian Implementations 6.4 Thin Templates 6.1 Receiving Notification of Changes in Rotation and Orientation 5.4 Platform Security 184.108.40.206.
2.2.2 Background Worker Class 7.5 Website Downloader 7.2.1 Basic Widgets Example 7.9 Messaging API 7.2.3 Service Framework Qt for Symbian and Mobile Extension Examples 18.104.22.168.Contents ix 7.2 Displaying Recent Messages 7.3 Bouncing Ball 7.10 Camera API 7.1.2 7.11 Location API 122 129 132 132 137 142 146 149 152 156 169 172 175 178 181 Index .7 FriendsApp 7.8 Sensor API 184.108.40.206.2.2.6 Stored Settings 7.4 Options Menu 7.
aau. Campus Hagenberg Softwarepark 11 4232 Hagenberg Austria andreas.dk Janus Heide Aalborg University Mobile Device Group Niels Jernes Vej 12 DK-9220 Aalborg Denmark email@example.com Tony Torp TAMK University of Applied Sciences Teiskontie 33 FI-33520 Tampere Finland tony. Fitzek Aalborg University Niels Jernes Vej 12 DK-9220 Aalborg Denmark firstname.lastname@example.com Hassan Charaf Budapest University of Technology and Economics Magyar Tudósok körútja firstname.lastname@example.com . Pedersen Aalborg University Mobile Device Group Niels Jernes Vej 12 DK-9220 Aalborg Denmark mvp@es. PB Brazil firstname.lastname@example.com Angelo Perkusich Electrical Engineering Department Electrical Engineering and Informatics Center Federal University of Campina Grande CP 10105 58109-970 Campina firstname.lastname@example.com Kyller Costa Gorgônio Signove Technology 58400-565 Campina Grande.P.dk Andreas Jakl Upper Austria University of Applied Sciences.ufcg. PB Brazil firstname.lastname@example.com Hyggo Oliveira de Almeida Computer Science Department Electrical Engineering and Informatics Center Federal University of Campina Grande CP 10105 58109-970 Campina Grande.fi Morten V. 1117 Budapest Hungary email@example.com Tommi Mikkonen Tampere University of Technology Korkeakoulunkatu 1 FI-33720 Tampere Finland firstname.lastname@example.com. PB Brazil firstname.lastname@example.com Frank H.ufcg.aau.aau.
bme. 1117 Budapest Hungary Imre.hu András Berke Budapest University of Technology and Economics Applied Mobile Research Group Magyar Tudósok körútja 2.hu Imre Kelényi Budapest University of Technology and Economics Applied Mobile Research Group Magyar Tudósok körútja firstname.lastname@example.com . 1117 Budapest Hungary andras.xii Contributors Bertalan Forstner Budapest University of Technology and Economics Applied Mobile Research Group Magyar Tudósok körútja firstname.lastname@example.com@aut. 1117 Budapest Hungary bertalan.bme.bme.
tools and testing teams. The whole of 2007 was spent on figuring out the right path to follow to go forward. S40 (proprietary) and Maemo (Linux). and the involvement of talented people created a good starting point. Nokia has had three active software platforms: S60 (Symbian). Each of these applications needed its own localization. Each of them has its own distinct syntax and its own distinct tools. S60 relied on Symbian AVKON and S40 had its own proprietary UI library. you just create an environment or system where you can share code or applications between software platforms and then you do not implement everything from scratch. Companies have their own development tools. The work for Open C started in the first half of 2005. but leverage open source innovations. The next step was to find a good solution for an application UI development. lastly. Qt was also well known for its consistent. Nokia Maemo was based on a GTK+ platform. the cleanliness of the APIs and architecture. especially in the mobile arena. These are known as PIPS (Posix In Symbian). Key libraries like libm. Qt is a powerful technology providing a great performance. libc and libpthreads were delivered to Symbian Ltd. The end result was that Nokia selected Qt as the next application development framework. All together we ported 5000 C-function calls to S60. This has been a dilemma for a long time. Nokia had at least three different solutions for it. No matter what the application was. it was self-evident that the overall development model was very expensive How then could this be reduced? How could a development model be created that the developers would love? How could a better return on software investments be provided? How could open source innovations be leveraged? The answer to this last question is very simple. As one software engineer stated: 'Qt gave the joy of programming back to me!' The way Qt was created. Thus. others for ease of development. stable. and is suitable for a distinct purpose. a . The starting point was quite complex. The commercial name was S60 Open C. Each of these platforms has its own set of software components and applications.FOREWORD The world is full of programming languages and development tools. but hard to actualize. programming paradigms and selected programming languages. robust and high-quality APIs and world-class documentation. then find a common application development framework for S60 and Maemo and. provide a standard and common way to access platform-level services in the mobile domain. The implementation plan was also very simple: port the standard C programming libraries to S60. Some languages can be designed for embedded devices. from mobile terminals to desktop environments. whether for a calculator or browser. and the same code can rarely be reused between different segments. First. Most open source middleware solutions are developed on top of standard so-called C programming libraries: good old POSIX and other key C libraries. Since the beginning of this century. but the most important thing was that developers loved Qt.
Examples of current crossplatform layers are Web runtime. like bearer management.xiv Foreword product loved by developers. This book is about how to develop Qt applications for Symbian.com Helsinki. I would like to encourage developers to develop applications which can be shared between platforms. Flash. Qt is a cross-platform development framework. 2009 . an open source development model and a way of mixing web and native technologies. Why not make full use of the benefits of Qt? Just download the latest Qt Creator from the Web and with this book start your journey! Mika Rytkönen mika. such as support for multitouch and a common way to access mobile platform-level services. enabling the development of applications across the Nokia device range. Nokia tendered a public offer to acquire Trolltech ASA. Together with the 'Trolls'. Today this is known as the Mobility API. in January 2008. The year 2008 was quite busy. However. Mac and Windows-hosted PCs and now also with Symbian. Nokia's software strategy for devices is based on cross-platform development environments. across Nokia's device portfolio and on PCs. The announcement stated for the first time the role of Qt and Open C as part of Nokia's software strategy: The acquisition of Trolltech will enable Nokia to accelerate its cross-platform software strategy for mobile devices and desktop applications. December. The same source code can be shared between Linux. we at Nokia started the R&D integration project. Java and Open C. With Trolltech. and develop its Internet services business. Nokia and third party developers will be able to develop applications that work in the Internet. layers of software that run across operating systems.rytkonen@nokia. Thus. Together we planned the missing pieces.
this book does not serve as a compendium either for Qt or for Symbian development. Even though the main focus is on Symbian devices. the book explains in detail the Symbian support available for Qt development in terms of APIs and the possibility to extend Qt applications with native Symbian. Qt has proven its strength for application developers for decades. Qt will provide cross-platform capabilities that allow porting of applications over a wide range of mobile devices. Throughout the book the authors link the reader to the appropriate sources. Additionally. Qt for Symbian will enable developers to create appealing mobile applications in a fast and efficient way. The main scope of this book is to explain to the reader how Qt applications can be created in an easy and efficient way on Symbian devices. Symbian experts (but not familiar with Qt) and Qt experts (but not . while Symbian offers the most flexible mobile platform due to its openness for a wide range of APIs. Grady Booch Motivation for the Book The main reason why the editors started this book project is based on the fact that Qt on Symbian will be one of the most important steps in mobile development for years. we expect our readership to fall into three main groups: namely. part of the code presented in the book can be ported to Nokia's Maemo platform or Windows Mobile devices. It has seven chapters. The book can be used for self-study as well as lecture notes for basic courses. As given below in Figure 1. such as web pages or books. total beginners.PREFACE The function of good software is to make the complex appear to be simple. Targeted Readership The book is structured to be useful for beginners and professionals in the field of mobile device development. The reader will be made familiar with how to install the development environment and use it. Scope of the Book To make it clear from the outset. Furthermore.
familiar with Symbian). while Symbian and Qt developers may skip Chapter 2 and Chapter 3. http://mobiledevices.aau. Beginners should read the book chapter by chapter. exercises and programming examples are presented.kom. where teaching slides.P. respectively. Frank H.xvi Preface Figure 1 The book's structure and parts that should be read (marked by a bullet) by beginners. These latter two may also skip the Introduction.dk/qt4symbian Note Snippets of code included in the book are to some extent based on documentation available at the time of writing. Tony Torp and Tommi Mikkonen December 2009 . and some of them have not been fully tested in real applications due to the relative freshness of the available implementations. Symbian or Qt developers. we would like to direct them to our complementary web pages. Fitzek. For teachers planning to use the book as their main lecture material throughout a course. The reader is referred to the latest available web documentation for exact details.
ABBREVIATIONS 3G Third Generation API Application Programming Interface ASCII American Standard Code for Information Interchange DOM Document Object Model DLL Dynamic Link Library FM Frequency Modulation FP Feature Pack FTP File Transfer Protocol GB Gigabyte GPL GNU General Public Licence GPS Global Positioning System GUI Graphical User Interface HTTP Hypertext Transfer Protocol IDE Integrated Development Environment IM Instant Messaging IP Internet Protocol IRDA Infrared Data Association JRE Java Runtime Environment LGPL Lesser GNU Public Licence MHz Megahertz .
xviii Abbreviations MMS Multimedia Messaging Service MOAP Mobile Oriented Applications Platform OEM Original Equipment Manufacturer OS Operating System PC Personal Computer RAM Random Access Memory ROM Read-Only Memory S60 Series 60 SAX Simple API for XML SDK Software Development Kit SIM Subscriber Identity Module SMS Short Messaging Service SQL Standard Query Language STL Standard Template Library SVG Scalable Vector Graphics TCP Transmission Control Protocol UDP User Datagram Protocol UI User Interface UIQ User Interface Quartz URL Uniform Resource Locator USB Universal Serial Bus W3C World Wide Web Consortium WLAN Wireless Local Area Network XHTML Extensible Hypertext Markup Language XML Extensible Markup Language .
We would like to thank Harri Pennanen and Jarmo Rintamaki from Nokia for encouraging us to start this book project. You would not be reading this book were it not for the key contributions of our invited authors as well as the kind support of Nokia and Qt software. Juliet Booker and Martin Tribe from Wiley for their help on the book. The work of Federal University of Campina Grande. Tony Torp and Tommi Mikkonen December 2009 . The work of Aalborg University has been supported by the Danish government on behalf of the FTP activities within the CONE Project (grant no. Manaus. Ralph Waldo Emerson This book is the result of the joint efforts of many people working together over the last few years. They have successfully kept up our motivation and enthusiasm over the last few months. Colleen Goldring. We would also like to thank Flavio Fabrício Ventura de Melo Ferreira. 09-066549). We are also greatly beholden to Knut Yrvin from Trolltech/Qt software. Brazil. Graham Henry. He encouraged us to incorporate Qt into our teaching environment and supported us with material such as the very first Greenphone and with travel funds over the years.P. Brazil. we greatly appreciate their logistical help by organizing numerous meetings to bring us together with other experts and programmers. Fitzek. Chris Webb. within the scope of the Pervasive Computing Project. Campina Grande. Ellie Scott. Frank H. We are deeply grateful to all our co-authors and industry (or 'other') supporters of this book. Besides the material support provided. We are particularly thankful to Birgit Gruber. has been partially supported by the Nokia Institute of Technology.ACKNOWLEDGMENTS The man who can make hard things easy is the educator. from Federal University of Campina Grande.
PUBLISHER'S ACKNOWLEDGMENTS Some of the people who helped bring this book to market include the following: Editorial and Production: VP Consumer and Technology Publishing Director: Michelle Leete Associate Director – Book Content Management: Martin Tribe Associate Publisher: Chris Webb Executive Commissioning Editor: Birgit Gruber Assistant Editor: Colleen Goldring Publishing Assistant: Ellie Scott Project Editor: Juliet Booker Content Editor: Nicole Burnett Copy Editor: Neville Hankins Technical Reviewer: Antti Svenn Marketing: Senior Marketing Manager: Louise Breinholt Marketing Executive: Kate Batchelor Composition Services: Compositor: Sunrise Setting Ltd. UK Indexer: Annette Musker . Torquay.
He is a well-known author and he has pioneered mobile devices programming in universities in Finland. He was selected to receive the NOKIA Champion Award in 2007.-Ing. in 1997 and his Ph.-Ing.P. During the past decade he has shared his knowledge among several Universities. he was awarded the Nokia Achievement Award for his work on cooperative networks. Germany in 2002 and became Adjunct Professor at the University of Ferrara. web development and agile approaches to software engineering.ABOUT THE EDITORS Frank H. he won the YRP award for the work on MIMO MDC and received the Young Elite Researcher Award of Denmark.) in Electrical Engineering from the Technical University Berlin. University of Aalborg.) degree in Electrical Engineering from the University of Technology – Rheinisch-Westfälische Technische Hochschule (RWTH) – Aachen. heading the Mobile Device group. Germany. he received the Nokia Champion Award in 2006. Denmark. VTT. (Dr. He has visited various research institutes including Massachusetts Institute of Technology (MIT). He has a strong software development background in the industry since the very first Symbian based smartphone projects in Nokia. Italy. 2008 and 2009. 2009 and 2010. and at present his research interests include mobile devices programming. cross layer as well as energy-efficient protocol design and cooperative networking. He received his diploma (Dipl. In 2008. . He is also running a company offering training and consultancy services for mobile developers. Tony Torp is a senior lecturer of software engineering at Tampere University of Applied Sciences where he is heading mobile systems education and running the smartphone lab of the University. Tommi Mikkonen is a professor at Department of Software Systems at Tampere University of Technology. Being one of the top developers in the field. In 2005. His current research interests are in the areas of wireless and mobile communication networks. companies and developer communities worldwide. He has held several different positions in academia and industry. and Arizona State University.D. Fitzek is an Associate Professor in the Department of Electronic Systems. mobile phone programming. He co-founded the start-up company acticom GmbH in Berlin in 1999.
SAMSUNG as well as Google plan to do in the near future. . at least a subset of them should be able to create those services. Fitzek. The chapter also explains the reasoning why Qt for Symbian is an interesting solution for a wide range of mobile developers – from rookies to experts – using the full functionality of the Symbian platform and enjoying the easy programming style of Qt in combination with its cross-platform capabilities. there was a common understanding across mobile manufacturers that the creators of the new and appealing services might not just be the network or service operators in collaboration with the mobile manufacturers. Furthermore. but that most of the services could be created by the mobile user. Or. user interaction as well as user friendliness. than in the pure technology. and the additional services will be provided by the developers. It took a while to appreciate that. would be the only viable solution to attract more customers. new channels are provided to promote and market those additional mobile applications. In order to enable customers to install new applications on their devices. and the available services on board.1 Introduction and Motivation Frank H. not a single application. Consequently. The reason why mobile manufacturers are so interested in increasing their developer base is due to the fact that the differences in mobile devices across different manufacturers are more in the design. We refer to this subset as mobile developers. It will underline the importance of mobile developers in the mobile communication ecosystem and why they should choose Qt for Symbian. utilities. Tony Torp and Tommi Mikkonen This chapter gives a short introduction to and motivation for the bundling of Qt and the Symbian platform. Apple with the Apple Store. health services and others. and as RIM. 1. since not all mobile users might be able to program. only a small number of mobile phones were programmable and so it was up to the network and service operators to think about the next killer application – a reflection of the misunderstanding that a single application could attract as much attention as was gained previously by the mobile voice service.1 The Importance of Mobile Developers It was at end of the 1990s when mobile phones had become so popular that the question was posed: what will come after mobile voice services? At this time. but a large number of heterogeneous applications. the manufacturers will take care of the design and a basic set of the most desired mobile applications. such as gaming.P. as Nokia is doing with OVI.
efficient and at the same time cross-platform supportive. This is true even for Java. At the moment there is a clear trade-off between accessibility (how fast a developer can learn a language) and functionality and efficiency (what the platform readily offers). The very first mobile applications were in the gaming area. For instance. The problem is how to provide a programming environment that is easy for mobile developers to access (accessible). not all the functionalities of mobile phones could be used. such as games or utilities like calendars or address books. once coded. independent of the programming environment. accessible. At the moment Java applications need to be tested on every single mobile phone to make sure they are working. Nowadays. mobile applications need to be tailored for individual phones or groups of phones. as given in Figure 1. which claims. they were subject to the restrictions of the early versions of mobile Java.1 Developer needs. If you want to reach a lot of users. Due to the given limitations.2 Qt for Symbian Figure 1. it is desirable to have a cross-platform approach which would reduce the time wasted by testing for different devices. Mobile developers have several programming languages and platforms to program for.1. Consequently. . Such marketplaces are important to allow the user of a mobile phone to install those applications that are needed and for mobile developers to monetize their work. which needed no connection to the functions of the rest of the phone. As this costs time. there is a further problem when one aims at the mass market. Therefore. From the perspective of mobile developers. to run everywhere. which in essence only provided a sand-box on which applications could be run and a very limited set of interfaces. that has enough flexibility to utilize the full functionality of the mobile phone (flexible) and that allows the produced code to run efficiently on the platform (efficient). the introduction of programmable mobile phones meant that the door was open for them to come up with services they always wanted to have or which they believed the mass market would like to purchase. since personal data of the user could not be accessed in early mobile Java implementations for security reasons. the number of supported mobile phones should be large. and they were based on Java. From the developer's point of view. the first applications were stand-alone applications that could easily be executed in a sand-box. the desired programming environment should be flexible.
who want simply to experiment with rapidly available applications. The goal of the platform is to allow developers to target a large mobile developer group. Another attempt to ease the developers' lot was Open C/C++ from Nokia (2010). Also. Instead of using a scripting language. for example. Moreover. In general.com/projects/pythonfors60/ extends the S60 platform with the Python programming language. A number of attempts have therefore been made to support mobile developers in approaching Symbian. and are provided with an option to create stand-alone S60 applications written in Python. However. say. but there still remain demanding coding issues regarding the user interface. a larger degree of freedom became available to developers because more functionality of the phones could be used. not to install additional program infrastructure. used short-range technologies such as IRDA or Bluetooth to exchange data among mobile devices.nokia. however. Symbian C++ has one big disadvantage over many other programming languages and systems. Besides these. Open C/C++ delivers an extensive range of standard C and C++ APIs. allows applications to be written once and deploys them . Open C/C++ allows the use of real C or C++ code. they can also be helpful when developing application engines and middleware based on already existing components. cross-platform development environment for developing applications efficiently.Introduction and Motivation 3 With the introduction of the Symbian platform and its programming language Symbian C++. This approach has solved some of the problems associated with Symbian development. Symbian also had the technological advantage of using native code. Nokia introduced Python for S60 (S60 is just a subset of the Symbian platform). Java developers. The reason for the marriage of Qt with Symbian is based on the fact that Qt. One of the very first applications was a dating client that checked for matching user profiles. or interfaced with the built-in facilities of the phone. This can be discouraging for some users. With the available infrastructure. even people who have never programmed before are now able to write their own script and realize their own ideas. Thus applications built with Symbian C++ consumed less resources and ran faster than other solutions at that time. The new degrees of freedom allowed the construction of mobile applications that. They are intended to help in porting desktop applications to Symbian devices. which can be extended to phone-related libraries to employ those functionalities too. resulting in a notification in the case of a positive match. Open C/C++ enables the reuse of already existing software assets and open-source components. as a cross-platform application framework. since the learning curve of Symbian C++ is rather steep. the Python interpreter is not readily available in off-the-shelf mobile devices but must be installed later on. flexible. Using the easyto-learn Python scripting language. Python for S60. which in turn results in additional installation tasks when using Python. On the downside. Being a C++ derivative extended with proprietary conventions and a somewhat complex application framework resulted in difficulties in its adoption by a large number of mobile developers. Consequently. Interested readers are referred to Scheible and Tuulos (2007) and Scheible (2010) for further information about Python for S60. developers are encouraged to undertake rapid application development and prototyping. released as open source at http://opensource. IP network connections using the cellular operators' network were possible. which provides exactly those four essential features mentioned above – it is an accessible. To open up the Symbian platform to a larger group of developers. The most recent step towards introducing Symbian programming to all mobile developers is the introduction of Qt for Symbian. the number of real Symbian C++ developers is quite low compared with.
which means that development becomes easier and developers get results much quicker. and the ability of Symbian OS to support the introduction of new features expected of mobile phones can be taken as a tribute to the original designers. the most widely used platform in today's smart phones. at least originally. whereas licensees developed different device-specific variations. and later EPOC32. including their philosophy in particular. The creation of the Symbian Foundation was announced on 24 June 2008 by major names in the mobile industry. The origins of Symbian OS lie in the designs of Psion PLC. Motorola and NTT DOCOMO. S60. and extensive use of object-oriented design. The origins of Symbian OS can be traced back to the 1990s and Psion mobile devices.2 Symbian OS Symbian OS is a leading-edge mobile development platform used in widely deployed mobile phones. open and complete mobile software platform in the world. Relying on C++. From a developer's perspective the complexity of Symbian is hidden behind interfaces provided by Qt. something which turned out to be important when the next steps towards the current smart-phone platform were taken. For further reading we will provide links to other work. which was to be named Symbian in its later life. the original home base of Symbian OS as we know it today. with much of the intellectual property originating from Psion PLC. including Nokia. the underlying Symbian platform guarantees the highest possible flexibility in providing all the functionalities of a mobile phone. The idea is to create a common understand among all readers for both technologies. We do not claim completeness for the individual parts. Qt APIs have been designed with crossplatform use in mind. from its origins at Psion to the newly created Symbian Foundation. and include in particular SIBO. a microkernel. In terms of technology. The path from the operating system of Psion devices to the Symbian platform – the most prominent Symbian environment in use today – has passed through numerous phases. or EPOC16. Being the state of the art at the time. The Qt APIs provide a higher level of abstraction than the Symbian APIs. the aim is to unify Symbian OS. Motorola. The goal of the foundation is to create the most proven. Moreover. it has enabled the development of a number of devices and given birth to Symbian. Furthermore. was established in 1998 to develop a mobile platform for smart phones. Psion's devices were modest in terms of performance and capabilities by today's standards. 1. which was based on C. and are commonly considered easy to learn and use. Sony Ericsson. The company was also developing associated software development kits to enable third-party application development. The development mode was such that the company Symbian focused on the core operating system and main frameworks. and UIQ for communicators relying on a touchscreen. . Nokia and Psion – the goal was to license Symbian OS to the manufacturers of advanced 2. including Symbian for phone-like devices. Originally owned by a number of major mobile device companies – Ericsson. Matsushita. The company Symbian. UIQ and MOAP(S) in an open-source platform for converged mobile devices. the authors of this book believe that it presents a timely topic and the following chapters should help developers to get started with Qt on the Symbian platform. Qt development is done in C++.4 Qt for Symbian across many operating systems without rewriting the source code. The rest of this chapter offers a short introduction to Symbian and Qt. As a result.5G and 3G mobile phones.
including application development (application framework) and generic event handling (active objects). Major changes in Symbian OS include at least the following issues. a new file is required in any case. The original Psion devices relied on RAM disks that were fast but required a separate backup during writes. . When the resource is used. A number of extensive frameworks are used for different tasks. the reception of which results in the generation of an event. error management is incorporated into the scheme. resource managers – communicate with their clients using messages. as servers – that is. 1. it is common for the microkernel to implement a message-passing mechanism which allows resource managers to communicate using the facilities that the kernel provides. The most characteristic design decisions are as follows. which is responsible for managing the resource. Over time. The design of Symbian OS is based extensively on object orientation. mobile devices commonly use flash memory for implementing disks. such resource managers are referred to as servers. and then establishes a session with the server. The latter is also associated with resource management. Since the main context of Symbian OS is smart phones. It is an operating system that is specifically targeted for systems with limited memory and resources in general. and if a client dies. the client first contacts the server. both of which will be addressed in the following. Symbian OS is based on the microkernel architecture. Every resource of the system is encapsulated into a server. the client can use the resources and services offered by the server.2. The term microkernel is commonly associated with a design where all resource managers that have access to the underlying hardware run in different processes and the operating system kernel only has minimal scheduling and interrupt handling responsibility. but their removal from the actual code base can be hard.1 Symbian – The Technology The design decisions of Symbian OS closely reflect its origins addressed above. As is common in microkernel approaches. Moreover. assumptions about available hardware have required redesign and reconsideration of numerous parts of Symbian OS. The use of the microkernel approach has resulted in the definition of special software components. Moreover. If a server is killed. the server should be able to release the allocated resources. the introduction of a microkernel has been an important goal.2. However. error messages are passed to the clients. Due to the physical characteristics of flash memory. After establishing the session. the improvement of off-the-shelf C++ systems has in principle rendered some of these conventions useless. Also.Introduction and Motivation 5 1. numerous proprietary conventions were introduced to cope with corner cases. the language used for implementing the majority of Symbian OS. whose purpose is to manage different types of resources. In the design of Symbian OS. were underdeveloped at the time of the design.2 Symbian – Evolution to the Leading Smart-Phone Platform As with any long-lived operating system. it is only natural that the evolution of their assumed facilities has also been the driving force of Symbian OS evolution. following the state-of-the art design from the 1990s. Hardware facilities have changed fundamentally. since programming facilities for C++.
processing capabilities have improved. this also marks a major breach in the compatibility between different devices in general. such as threading and interfacing to subsystems such as SQL database and XML parsing. the evolution of the platform has led to complications that are visible to a casual developer. their cumulative effect in incorporating support for all of them has added to the complexity of Symbian OS.6 Qt for Symbian The amount of memory in different mobile devices has increased tremendously. Although commonly associated with GUI programming. The number of different subsystems that can be attached to current mobile phones has increased. For a device manufacturer. Qt for Symbian is an interesting solution. this phase also marks a major disruption in the evolution of Symbian OS. many considerations regarding the use of memory that were a necessity in early mobile phones using Symbian OS are no longer needed. For an application developer. Symbian's microkernel-based approach is well suited for this. This is considered frustrating when the development of applications for Symbian OS is performed only occasionally.3 Symbian – Casual Application Developer While the facilities of Symbian OS have been improving under the hood. not to mention binary compatibility. the adaptation interface between Symbian OS and underlying hardware resources which originally consisted of only a few servers has grown into a complex framework. the system also includes numerous other components. 1. where a plug-in architecture is used for variability between different hardware components. Qt is a cross-platform application development framework that is widely used for the development of GUI programs. but different extensions obviously require engineering efforts to integrate them into complete Symbian-OS-based systems. The introduction of platform security has required a major redesign of Symbian OS. especially when considering the tasks of an application programmer. the microkernel architecture has proven to be a flexible platform for complex applications. more and more processing-capable peripherals have been introduced. and embedding resources in servers has provided a practical approach for managing the ever-increasing number of new resources associated with mobile phones. Consequently. however. which can be considered as superfluous complexities by an application developer. which is to be used as the basis for developing applications with a graphical user interface (GUI). Indeed. generates standard C++ code. For example. . individual subsystems have become increasingly complex. Consequently. these issues remain valid. Internally Qt is based on C++. In general. Symbian OS's ability to sustain the above is a tribute to the original design that still forms the core of the operating system. On the downside. In addition to the increase in clock frequency. however. Besides Python and Open C/C++. for a casual programmer Symbian OS's facilities have remained somewhat challenging. At the same time. The challenges can be associated with two particular design choices: the Symbian application architecture. which were major improvements in the state of the art in the early 2000s when the first Symbian-based mobile phones were introduced. Qt runs on all major platforms and supports internationalization. As a consequence. In particular. which was also breached. especially in the form of evolving documentation. In parallel with the increase in the amount of memory. and a number of platformspecific details. which. but it includes several non-standard extensions implemented by an additional preprocessor. it is not uncommon to find hundreds of megabytes of available memory and gigabytes of disk.2.
In addition to the same APIs. and in some cases more importantly. In addition to APIs and cross-compilation support.3 Qt Qt (pronounced cute) is a product of QtSoftware which was originally named Trolltech (founded in 1994). From the developers' point of view the supported Qt APIs remain the same across the supported platforms. in 2006 Trolltech introduced the Greenphone. tools supporting Qt development were introduced. the same toolchain is available for different computing systems to support similar development experiences.3.1 A Cross-platform Development Environment The main idea behind Qt was the possibility to program an application in C++ or Java once and deploy it across many desktop and embedded operating systems without changing the code at all (see Figure 1.2 Qt in the Mobile Domain In the beginning Qt was targeted at Windows. Skype.0) and Linux systems only. when using Qt the resulting applications should look like a native program of the given platform to ensure user friendliness – namely. such as those offered in mobile devices only.3 shows the look of Qt buttons for multiple platforms.2). the very first prototype was ready in 1993. Figure 1. the approach was so appealing that it was quickly expended to embedded systems in 2000.9. Based on the initial idea of creating an object-oriented presentation system. which is a fully featured mobile phone based . Moreover. see Yrvin (2010). 1. which in turn results in increased productivity over different toolchains targeted for different contexts. such as Qt Designer or Qt Linguist. which could cause some irritation to the customer who is used to a given handling of the applications. adaptive look and feel. 1.Introduction and Motivation 7 Figure 1. Qt comes with an intuitive class library and integrated development tools offering support for C++ and Java development. Finally. the user interface would always look the same. Mac OS (starting with Qt 3.2 Qt development process: program once and use multiple platforms. However. 1. the first public release was launched under the name Qt 0. The name was a result of the nicelooking letter Q in the Harvard Emacs editor and the Xt technology. Over the last few years Qt has been used by many customers such as Google. provided that the developers are using common APIs only and do not use device-specific interfaces. Volvo and many more.3. and Trolltech was founded one year later in Norway. On 20 May 1995. In contrast to Java's SWING module where the application would also possibly run on all different platforms.
8 Qt for Symbian Figure 1. Figure 1. In addition to the existing programming languages of Java. the introduction of Qt and its toolchain to mobile devices will reduce the number of hurdles to creating a mobile application. But as this is a two-way street. In the mobile domain Qt is available on Linux-enabled devices and Nokia has pushed Qt onto the Symbian platform. Symbian C++. In order to enable Qt to use the full range of mobile functionalities.4a). Python or Flash. Together with the technology Nokia achieved access to a large and agile programming community. The vision of Qt has been to introduce it everywhere – covering both the desktop and the mobile domain.4b shows the user interface of the Greenphone. In 2008 Nokia took over Trolltech and introduced Qt to its platforms starting with the Symbian and Linux platforms. on Linux (see Figure 1. such .4 The very first Qt mobile phone. (a) The Greenphone (b) User interface of the Greenphone Figure 1. Qt programmers can now access the mobile domain with millions of new target devices yearly. The Greenphone already had a touchscreen and a number of wireless air interfaces.3 Qt look and feel for multiple platforms.
As long as pure Qt language is used. On the other hand. as those that are not available in the desktop world. inbuilt sensors and many more things. new Symbian APIs need to be introduced.5 The cross-platform capabilities of Qt source code on different mobile platforms. . Symbian APIs can only be used for the Symbian platform and may be extendable later for other platforms of the Nokia ecosystem. Such an approach is similar to the Qt embedded approach. where functionalities such as phone-related access of calendars and contacts or the use of wireless short-range Bluetooth are limited to the embedded environment.5 illustrates the applicability of Qt software for different platforms. These APIs are responsible for using localization information. Figure 1. mobile messaging such as SMS and MMS. social mobile networks and many others. but obviously those APIs have the potential to create real mobile applications for location-based services. including desktops and laptops. Of course it is possible to create mobile applications for the Symbian platform without using the newly introduced APIs. the code should work on any platform. Nokia ecosystems and third-party mobile devices.Introduction and Motivation 9 Figure 1. cameras.
1 License Agreements of Qt.0.0 or are otherwise willing to comply with the terms of GNU GPL version 3. . The latter allows developers to monetize their applications without making their source codes public. to those with valid maintenance Yes. Qt GNU GPL v3.0 This version of Qt is appropriate for the development of Qt applications where developers wish to use such applications in combination with software subject to the terms of GNU GPL version 3. the LGPL has only been added recently. freely distributed Not included but available for purchase separately No Not included but available separately for purchase No Charge for runtimes 1. Qt is offering different licence models. It is for developers who do not want to share the source code with others or otherwise comply with the terms of the GNU Lesser General Public Licence version 2.1. modifications can be closed Yes – no source code must be disclosed Yes.1 This version of Qt is appropriate for the development of Qt applications (proprietary or open source) provided developers can comply with the terms and conditions contained in GNU LGPL version 2. in accordance with the LGPL v2.3 Qt Licensing The most important issue for mobile developers is the licence agreement.1 or GNU GPL version 3.0. freely distributed GPL version Free Source code must be provided No. Qt GNU LGPL v2. Qt is available under the following licences: Qt Commercial Version This version is the appropriate one to use for the development of proprietary and/or commercial software. applications are subject to the GPL and source code must be made available Yes. Commercial version Licence cost Must provide source code changes to Qt Can create proprietary applications Updates provided Support Licence fee charged No.1 terms Yes. While the commercial and GPL versions have been present from the beginning.3.10 Qt for Symbian Table 1. freely distributed Yes LGPL version Free Source code must be provided Yes.
Inc. Oral Presentation Material. Scheible J 2010 Python for S60 tutorials.1 the licence agreements are compared with each other. Yrvin K 2010 Qt introduction. Scheible J and Tuulos V 2007 Mobile Python: Rapid prototyping of applications on the mobile platform.com/Resources_and_Information/Explore/ Runtime_Platforms/Open_C_and_C++/. http://www. Bibliography Nokia F 2010 Open C and C++.htm.forum.nokia. .com/pys60/menu. http://www. John Wiley & Sons.mobilenin.Introduction and Motivation 11 In Table 1.
1 Installing the Development Environment Figure 2. Frank H. 2. it is recommended that you scan through the first part of the chapter as some SDK versions require patching or similar. 2 GB RAM and enough free hard drive space for the tools. the only currently supported development platform is Windows and it is recommended that users run either Windows XP or Windows Vista. This restriction is due to the fact that some tools in the Symbian platform SDK are only available on the Windows platform. before proceeding to Section 2.1 shows an overview of the components that comprise a typical Qt for Symbian development environment.1.P. The sections following will go through the process of creating and running a 'Hello World' application using Qt for Symbian both in the emulator and on a mobile phone. Once this is installed we can extend it also to support Qt for Symbian development. the first tool we need to install and set up is a working Symbian development environment. This installation process may take several hours depending on which components you install. Linux or Mac. If you already have a working Symbian development environment and are familiar with the tools and application build process.e. so this requirement will therefore most likely be removed in future versions of the Symbian platform SDK. a table containing the original links can be found at the end of the chapter. it is recommended that a reasonably fast development PC is used. e. Pedersen. an 1800 MHz processor.2 Getting Started Morten V. Fitzek and Tony Torp This chapter gives an overview of the tools used for Qt development for the Symbian platform. i. There is. IDE and SDK. During the installation you will need to download approximately 1 GB of tools and updates. In addition to the current Windows requirement.3 GB installed. however. In the following we will go through the installation of the individual components. an ongoing effort to add official support for other development host environments. All tools take up approximately 2. Assuming that we already have a working Windows development machine.7 which focuses on the installation and introduction of the Qt for Symbian SDK. Janus Heide. . Note that throughout the chapter some long download links have been shortened using a URL shortener service. As indicated in the figure. The early sections will serve as an entry point for developers who are new to the Symbian platform by providing a step-by-step introduction and installation guide to the tools needed.g. If a shortened link does not work.
java. this step can be skipped. However. After installing the Ovi Suite you can connect your Symbian device to your development machine using either Bluetooth of a USB cable. 2. Download: http://www. If you already have the Nokia PC Suite application installed. Here you may install the latest available Java version. Download: http://www. The phone emulator is a valuable tool in the development and testing of our applications. it is recommended that it is installed as it enables easy transfer and installation of applications to the phone.com/exploreservices/ovi/ovisuite 2.1. the Ovi Suite is an optional component. a working installation of the Java Runtime Environment is necessary.com/en/download/ . Note that installing a JRE above version 5 may cause the error 'Cannot start ECMT manager' to appear when trying to access the preferences of the Symbian emulator.ly/7WCpIf.2 Java In order to utilize the phone emulator fully.1. If you do not intend to use the device emulator.14 Qt for Symbian Figure 2. as the PC Suite software provides similar functionality.nokiausa.1 Overview of the tools comprising a Qt for Symbian development environment.1. to resolve this problem see: http://bit. you may skip this installation.1 Ovi Suite As shown in Figure 2.
you may select any of the above-listed SDKs. E75. The officially supported version is ActiveState Perl version 5.4 Example devices 5700. E71. Should you need to access features of the Symbian platform not yet available through the Qt libraries. You will find that there are a number of different SDK versions. each targeting different Symbian platforms.1. since with Qt we may use any of the mentioned SDKs for application development and deployment. however.Getting Started 15 2. headers. in the device specification section on Forum Nokia (http://www. E63. However. 6650. The following table shows the platforms that currently support Qt for Symbian development: Platform S60 3rd Edition Feature Pack 1 S60 3rd Edition Feature Pack 2 S60 5th Edition (Symbian^1) Symbian OS version v9.ly/4vOXGX Note: The ActivePerl package should be installed before installing a Symbian SDK. This is. and so forth. This change is so new that we still use the vendor-specific SDKs during development. Symbian^3. Without a physical device you will still be able to test and run your applications in the .nokia. During the installation of ActiveState Perl ensure that the 'Add Perl to the PATH environment variable' option is checked.1. compiler. Of these the two most well-known UI platforms were the S60 platform used mainly by Nokia and the UIQ platform used mainly by Sony Ericsson and Motorola. E55. otherwise the installation might fail. Download: http://bit. These will be named Symbian^2. N97 Note that in this table the first Symbian Foundation SDK (Symbian^1) is a copy of the S60 5th Edition SDK.6. If you do not have a suitable device available.2 v9.3 Perl Several of the build scripts in the Symbian platform SDK rely on Perl. N82. 6120. not necessary with Qt for Symbian. libraries and additional tools that are needed to build applications for a Symbian device. Note that if you install a different version of Perl the Symbian build toolchain may not function properly. future versions of the Symbian Foundation SDKs will replace vendorspecific SDKs. When developing applications using native Symbian C++ APIs. Historically Symbian delivered the core operation system.3 v9. Note that platforms prior to the 3rd Edition Feature Pack 1 do not support Qt for Symbian. for a specific target device. However.forum. N85.1 build 635. which was then extended by different vendors using their own UI platforms. since the Symbian Foundation was formed in 2008 these have now been merged into one platform maintained by the foundation. you have to use an appropriate SDK determined by which version of the Symbian and UI platform your target device uses. N96 5800. you can determine which SDK you need. N95 5730. 2.4 Symbian Platform SDK The Symbian platform SDK includes the documentation.com/ devices/).
ly/4qdgTk If you are installing the 3rd Edition Feature Pack 2 or 5th Edition SDK the installation files can be found by pressing the 'Download all-in-one S60 SDKs' button. However. C:\Symbian\9. accept the licence agreement. and install the 'CSL ARM Toolchain'. choose a 'Typical' installation. This means that applications built with. the installation can be completed in the following three steps: 1.exe file in the temporary directory.nokia.exe file needs to copied to the epoc32\tools sub-directory. e.g. there are exceptions. for example. so it is recommended to install multiple SDKs and build the application for each platform. i.g. The SDK is delivered in one zip file. choose the default options. 2. If you are installing the 3rd Edition Feature Pack 1 SDK you will find the installation files by pressing the 'Download S60 SDKs for C++' button.e. If you wish to target several different S60 platforms. Follow the installer. e.16 Qt for Symbian device emulator. Installing the Symbian SDK In order to download the SDK you will need a valid Forum Nokia account which can be obtained at http://www.com/Sign_Up.forum. it is perfectly acceptable to install several different SDKs. After completing the registration and logging in to the Forum Nokia website. Overview of the Symbian SDK This section provides a brief overview of the SDK and the contents. If you are installing more than one of the SDKs supported by Qt for Symbian and are using the default suggested installation paths. you will notice that the SDK root directory since 3rd Edition Feature Pack 2 is installed under S60\devices\SDKversion and older SDKs . Note: If you choose to use Symbian C++ native code/extensions the different platform SDK versions are to some extent backward binary compatible. 3. a 3rd Edition SDK in most cases also run on a 5th Edition device.exe file can be downloaded from: http://bit. where to find Symbianspecific documentation.2\S60_3rd_FP1\epos32\tools. The updated getexports. A new version of the getexports. Run the setup. After downloading. you may download the SDK from the following location: Download: http://bit.xhtml free of charge.ly/8KMG9K. Patching the 3rd Edition Feature Pack 1 SDK In order for Qt for Symbian to function properly with the 3rd Edition Feature Pack 1 SDK we need to apply one additional patch to the installation: 1. Unzip the contents to a temporary directory.
ly/R1C2q 1 Variant refers to the build variant. 2. support for the C++ Standard Library. Later. you will see a number of Symbian-specific files being generated. several SDK sub-folders have changed names. In addition. e. typically S60 platform specific Development tools. and should be replaced with udeb for debug builds and urel for release builds. However. . The following table gives an overview of selected folders in the SDKs and their contents: 3rdFP1 Edition Epoc32 Examples Series60Doc Series60Ex Series60Tools 3rdFP2 and 5th Editions Epoc32 Examples docs S60CppExamples S60tools Description Contains cross-compiler.Getting Started 17 are installed under Symbian\OSversion\SDKversion.2. which contains various help files. emulator and system headers and libraries Non-S60 specific Symbian OS code examples The SDK documentation files. the build tools assume that we are building system applications and therefore place them in z:.1 When building for the emulator.g. However. the SDK does not include the Open C/C++ version 1. During building for the emulator the drives are mapped into the following directories: c: is mapped to \epoc32\winscw\c.g. Here you will also find the Symbian Developer Library containing searchable guides and API documentation. SVG to SVG-T converter The epoc32 folder containing the emulator also contains the drive mapping used when testing applications in the emulator.c++ help menu. We therefore have to install the plug-in into our installed Symbian SDK: Download: http://bit. e. Note that on the target device the z: drive is used for the ROM and contains the operating system files and standard applications.1. The Open C/C++ plug-in provides developers with standard C and C++ libraries. The c: drive provides both memory for running processes and storage for new applications. when we create our first Qt for Symbian application.6 plug-in required by Qt for Symbian. Another important folder is the documentation folder. This library may also be accessed from the Carbide. z: is mapped to \epoc32\release\winscw\variant\z. see Figure 2. including API descriptions Code examples. files created while the application is running in the emulator will be placed in the c: directory. The SDK documentation can also be accessed via the Windows Start menu under 'S60 Developer Tools'. the purpose of these is described in the Symbian Developer Library.5 Open C/C++ Plug-in We now have the Symbian platform SDK installed and ready for use.
2 SDK documentation containing essential information about the Symbian APIs. Note: For new users it is recommended that all software is installed into the suggested default directories. Select the SDKs that you wish to use for Qt development. Unzip the contents to a temporary folder. The plug-in is contained in a single zip file.18 Qt for Symbian Figure 2. The registration process is done via a registration wizard which requires that you can access your Forum Nokia web page account. The Open C/C++ libraries also need to be installed onto our target device. Symbian OS architecture. The Open C/C++ plug-in must be registered the first time you use it. as some applications have special requirements for the installation paths. gives you a 14-day trail before requiring registration. accepting any further default values. The installer will automatically detect our installed SDKs. if you have a default installation you can more easily find useful 'how-tos' and similar advice on the Internet. Furthermore. We will do this when installing the Qt for Symbian libraries.exe file in the temporary directory. 2. and continue the installation. Note: Both the Open C/C++ plug-in and the S60/Symbian SDK will require that you register your usage of them online. 4. Run the setup. however. Installation of the Open C/C++ plug-in can be done in the following steps: 1. development tools and programming idioms. . 3. the SDK.
Getting Started 19 2.c++ available from Forum Nokia's webpage is version 2. Qt for Symbian requires building projects to be enabled from the command prompt. 4. Go to download URL and press the 'Download Carbide.ly/6Rzaba 1. including additional features such as on-device debugging Extends the features of the Developer Edition with tools for performance analysis and extends the on-device debugging capabilities with systemlevel and crash debugging Extends the features of the Pro version with tools needed by manufacturers when creating phones using Symbian OS OEM All three variants can be used for Qt for Symbian development.c++ will store new projects.c++ IDE The recommended IDE by Symbian and Nokia is currently the Eclipse-based Carbide.c++ you will be prompted to select a workspace where Carbide.2.exe file and choose the default options. select Search for update of the currently installed features and click Finish.c++. Run the downloaded . The Carbide.0.c++ is available for free in three different variants: Variant Developer Pro Features Contains the tools needed to develop applications for S60/Symbian. If this is your first time starting Carbide. As the update dialog appears. 3. you must perform an update. since Qt for Symbian currently requires Carbide. If you have no specific reason to change it.1. However. which is done from within the IDE.6 The Carbide. 2.c++ variant to install and select the installation directory. Carbide.c++' button. and all three are included in the Carbide.c++. select the default directory suggested by Carbide.c++ IDE provides support for creating.c++ version 2. The update option can be found in Help → Software Update → Find And Install. managing and building applications developed for the Symbian OS and S60 platform devices.0. choose the Carbide. The following steps will take you through the installation process: Download: http://bit. i. This can be done by locating Carbide. if you are unsure which is the closest.c++ installer which may be downloaded from Forum Nokia (you select your preferred version during the installation).e. Note that this process may take in excess of 20 minutes. Once the update manager has found the updates available. accept the licence agreements. you will be prompted to select an update mirror.c++ → Configure environment for WINSCW command line under the Windows Start menu. Currently the latest version of Carbide. select Automatically select mirrors and press OK. Select all updates and accept the licence agreement and the update process should start. .
If the compiler version is older than what was specified above. Here we select 'Qt libraries 4. The compiler version number can be checked by executing the file mwccsym2. In the following we install the Qt for Symbian libraries which will allow us to start developing Qt applications for our S60 devices. C:\ProgramFiles\Nokia\Carbide. it contains the documentation. On the download page you can choose which licence you wish to use – in this case choose the LGPL tab. 2.5.com/downloads 1. but might. Note: If you also plan to do native Symbian C++ programming the patch should not.g. After applying this last patch we now have completed the installation of the common tools used in a standard S60/Symbian development environment. The updated can be downloaded from: http://bit. C:\ProgramFiles\Nokia\Carbide. you should create a backup of the x86Build directory before applying the patch. interfere with your Symbian builds.exe file. A new version of the compiler needs to copied to the x86Build sub-directory of your Carbide. Patching the Carbide Compiler To make the environment work properly we need to apply one patch to the Carbide. The Qt for Symbian distribution is delivered in one . build 482 to be able to build Qt for Symbian properly. you should update your installation using the following steps: 1.c++v2. This section will guide you through the installation: Download: http://qt.exe. e. To ensure that you can always revoke the changes. headers and libraries needed for Qt for Symbian development. e. which will show the available LGPL downloads. Qt 4. From the menu bar select Window → Preferences.c++ to use a proxy server: 1.exe from the command line.c++ installation.nokia. Expand the General tab and select Network Connections.c++ installation. at the time of writing. Select Manual proxy configuration and enter your proxy settings.6 for Symbian'. c++v2.7 Qt for Symbian The latest version for Qt for Symbian is.1.g. 2. 2. this is necessary as the Carbide compiler needs to be at least version 3.0\x86Build\Symbian_Tools\Command_Line_Tools\mwccsym2. Download this .6.0\ x86Build.20 Qt for Symbian Note: If you are behind a proxy you will need to configure Carbide.2. Download the Qt for Symbian package from the URL above. .exe file to your hard drive and double-click it to start the installation.ly/5fQEj4.
you should change the destination folder to. Note that we must select a folder on the same drive as where we installed the Symbian SDK.c++ IDE. Specifically for Qt for Symbian. You may revisit the welcome screen at a later stage by pressing Help → Welcome.0-symbian).c++ to use the Qt for Symbian distribution. The welcome screen contains a number of shortcuts to tutorials. for Windows application development. In the folder locate the file called qt_installer.Getting Started 21 3. Installing Qt on the Device Before we can run Qt applications on our mobile device we need to install the Qt for Symbian libraries on to our device. which can be accessed by pressing the Workbench icon in the top right corner of the welcome screen. 2. We are now ready to start building applications using Qt for Symbian. In the next step we need to set up Carbide.c++ you will be greeted with the Carbide. Under the Qt preferences click Add and in the Add new Qt version dialog enter the Qt version name. This can be done in the following steps: 1.0-symbian to allow other Qt versions to be installed in the same folder.3. C:\Qt\4.c++ Open Carbide.6.g. etc. 2. Development and project management are done in the workbench window. Navigate to the Qt folder where we just installed the Qt libraries and tools (in our case. The workbench window shown in Figure 2.sis – this file contains the Qt libraries for the phone packed in a Symbian installation package (. e.2 Using Carbide. The Qt installer will detect our installed Symbian SDKs and ask which one we want to use for Qt development.sis file). C:\Qt\4. The first time you start Carbide. Also. 4.c++ welcome screen. Assuming you have installed the Ovi Suite and connected your mobile device through either USB or Bluetooth. if you wish to use other versions of Qt. say. The Qt development guide may also be accessed via Help → Help Contents. Here we can simply add support for all Symbian SDKs by selecting all the SDKs currently installed and pressing Next. you may access Overview → Qt Development.6. . This is done from the application manager found on the device. you can now double-click the file and Ovi Suite will start the application installer on your device. Then we have to choose the destination folder for the Qt libraries.c++. Uninstall any previously installed Qt or Open C/C++ libraries that may be on the device. the path to the bin and include directories in the Qt installation folder as shown in Figure 2. release notes. go to Window → Preferences and select Qt. Configuring Qt Support in Carbide.4 can be broken down into the following main elements: Project explorer This shows the folder structure of the current projects and allows for navigating the files.c++ with Qt for Symbian This section provides an overview of the Carbide.
e. Editor Used for viewing and editing source files.22 Qt for Symbian Figure 2. The application wizard will show the following available project templates for Qt projects: . This collection of views/windows is called a perspective in Carbide.g.3 Qt properties must be updated in Carbide. There are other useful perspectives such as the Debug perspective that contains the windows/views useful during a debug session.g. Creating a 'Hello World' Application Now we can create our first project using the Carbide. the Qt C++ Property Editor and other Qt-related windows. and the Qt C++ perspective which we will use during Qt development.g. Also in the following we will go through the basic steps of creating a 'Hello World' application using Qt for Symbian. Output window This window allows for several different views. e.). Toolbar: Among other things this contains the 'Build' button which allows for building the current project.c++. The perspective can be changed using the Window → Open Perspective menu item. the Problems view that display problems encountered during the build process of a project and the Console view which displays the output from the build process (compiler. and the 'Run' button which launches the application for functional testing.c++ Project Wizard. the 'Debug' button which launches the application in debug mode.c++ terminology. the Qt C++ Widget Box. If you switch to the Qt C++ perspective you will notice that some additional windows appear in the workbench. allowing for inspection of variables and breakpoints. The project wizard can be found under File → New → Qt Project. e. etc. We will use these in the following when working with new Qt for Symbian applications. linker.
Switch perspective shortcuts Output window Project Explorer Shows active projects Collection of views useful during application development e. Console: Shows output from compiler and if configured correctly output from emulator.c++ workbench screen. which provides the basic functionality used in a dialog GUI application based on the QMainWindow class which provides a more sophisticated user interface option Simple GUI application based on the QWidget class . Qt C++ Widget Box tab Run Button Starts emulator and runs application. are processed Simple GUI application base on QDialog. File Editor Modify files in the project.4 Carbide. Qt C++ Property Editor Figure 2.Getting Started 23 Build Button Select the build configuration and build project. Problems : Shows warnings and errors issued during compilation. timer events.g. etc.. Template Qt Console Qt GUI Dialog Qt GUI Main Window Qt GUI Widget Purpose Used for applications not requiring a GUI and provides the Qt event loop where network.
24 Qt for Symbian Select the Qt GUI Dialog template and press Next. *.mmp The component definition (bld. *. To add a component switch to the Widget Editor view.rss The *_reg.mmp) file are used to describe the files contained in a Symbian project. double-click it and it will open in the Editor window.pro file and we should therefore use the .cpp These are the standard C++ source files containing the code used in the project. To see how the application looks. To add GUI components we may use the Qt Designer Editor. *. *.rss A standard Symbian resource file. In the following dialog specify the name of the new Qt for Symbian project. However.pro file when changing project settings. when building the project from the command prompt. This can be done by double-clicking the . press Qt C++ Widget Box in the upper left corner next to the Project Explorer tab.inf and *. dialogs. they are used. for example.sis. Change the label's text to 'helloworld'.loc The .pkg A Symbian package file.inf/*. select the SDK you wish to use and press Finish. The application wizard will show a dialog containing a list of SDKs and build configurations that you can use for the project. *. application icons and captions. in this case choose helloworld.pro file contains information about our application that is needed for the Qt build tools when building our application.c++ now creates the project and switches to the Qt C++ development perspective.inf) file and the project definition (*. as shown in Figure 2. Using Qt for Symbian these files are generated automatically from the . The .ui file. *. Using the Property Editor we can manipulate a wide range of additional parameters controlling the appearance and functionality of the widgets.loc file can be used for localization if the application must support multiple languages. it is needed by the Symbian application launcher or system shell. build the project and run it in the S60 emulator by first pressing the 'Build' button to build the project and thereafter the 'Run' button as previously shown in . and press Next. Changing the label text can be done by either right-clicking the label and selecting Change plain text or by selecting Qt C++ Property Editor and locating the text property for the label widget.ui The Qt .mmp files.pro file. Say 'OK' to adding headers and sources to the . The project is now ready and we can build and run it in the emulator. In the Project Explorer view observe that the application wizard has created a number of files for the new project: *_reg.pro The Qt project file.ui file is used by the GUI design tools to describe the components and properties of a GUI application. Select the Label widget and drag it to the Editor window. which should automatically open the design editor. Carbide.h/*. used when creating Symbian installation files . since the application wizard created an empty project we should first add some functionality to the application. which serves the same purpose as the bld. A resource file is used for defining a number of UI elements such as menus. Makefile Automatically generated makefile for project compilation. The list depends on the SDKs installed.rss file is a special Symbian resource file containing information about the application. *.5. To edit one of the automatically generated files.
. so be patient. There are two ways to achieve this: either edit the \epoc32\data\epoc. Select Tools → Preferences and choose the Enable EPOCWIND. which may be accessed from the Run command in the Windows Start menu. Figure 2.out can be found in the Windows temporary directory. Now that the application runs in the emulator we will configure the build process for a physical device. by typing %temp%. This can take some time. If all goes well you should see the emulator start and launch the application. you can find valuable information by inspecting the debugging output from the emulator. or control the same setting through the emulator's preferences menu. Note: If something unexpectedly does not work. You can read more about using the emulator by searching for the keyword 'emulator' in the Help → Help Contents menu.4.Getting Started 25 Figure 2.OUT logging option. The log file named epocwind.5 Using the Qt C++ perspective to design the UI of the application. For the S60 3rd Edition this first needs to be enabled.ini file where the line LogToFile 0 must be changed to LogToFile 1.
Note that if Carbide.6.forum. The following table summarizes a number of good Internet resources where additional information or help may be obtained: Forum Nokia Discussion Boards Forum Nokia Wiki Forum Nokia Developer's Library Qt Developer Zone http://discussion. Make sure the Ovi Suite is connected to your phone and then simply double-click the .c++ does not build the .sisx file in the Project Explorer view so that the Ovi Suite application installer will be activated and allow you to begin the installation on the phone.sisx file should be created. Rebuild the project and the . Building for a Target Device In order to deploy the application on a phone we need to change the build configuration.com http://wiki. This can be done through Project → Properties → Build Configurations and selecting the 'Phone Debug (GCCE)' configuration.sisx (Symbian installation file).nokia.forum. You should be able to find and run the application from the phone menu.com http://library. run them in the emulator and on a physical device.pkg file to the SIS build property. Press 'OK' to accept the changes and go to the Qt C++ perspective. Under the 'SIS Builder' tab add the . namely the helloworld_gcce_udeb.26 Qt for Symbian Figure 2. The easiest way to install the application on a phone is to use the Nokia Ovi Suite application installer and a Bluetooth dongle or USB cable.nokia. we can use the Project → Build Project menu option.6 Selecting an active build configuration.com/developer . Complete the installation on your phone.forum. You should now be able to create new applications. we have to add the .nokia. As when building for the emulator.nokia. but we will do it by selecting the project from the Project Explorer tab and then using the Project → Build Configuration → Set Active → Phone Debug (GCCE) menu option. The new active build configuration is now marked as shown in Figure 2. You can leave all other options as they are.sisx file.3 Summary In this chapter we installed and tested our Qt for Symbian development environment. 2. which will create a new file in Project Explorer. This can be done in several ways.com/ http://qt.pkg file.
zip http://pepper.ly/4vOXGX http://bit.ly/R1C2q http://bit.ly/6Rzaba http://bit.no/ s60prereleases/patches/x86Tools_ 3.troll.nokia.nokia.forum.com/id/ 91d89929-fb8c-4d66-bea0-227e42df9053/ Open_C_SDK_Plug-In.ly/4qdgTk Original URL http://www.html http://pepper.forum.ly/8KMG9K In the following chapter the cross-platform Qt API is introduced.forum.com/Resources_ and_Information/Tools/IDEs/Carbide.6/ http://www.5_Symbian_b482_qt.ly/7WCpIf http://bit. c++/ http://www.nokia.activestate.com/index.troll. com/info/sw.forum. upon which most of our Qt for Symbian applications will be built. exe http://bit.com/Resources_ and_Information/Tools/Platforms/S60_ Platform_SDKs/ http://wiki. php/KIS001066_-_'Cannot_start_ECMT_ Manager'_error_message_in_emulator http://downloads.no/ s60prereleases/patches/getexports.ly/5fQEj4 http://bit.com/ ActivePerl/Windows/5.nokia.2.nokia.Getting Started 27 Links The following table shows the mapping or URLs used throughout the chapter: Short URL http://bit. .
create a file called main. The generic Qt code works everywhere. See Figure 3. it is still important to know how the user interface elements work. the aim of this application is to show the text 'Hello World' on the screen. Of course. let us create the typical Hello World application. argv).c++. make sure that the full path to your project directory does not contain any space characters and that it is on the same drive as the Symbian SDK. before outsourcing this task to the designer tool. As a result. This also requires directly working with the Qt classes. let us do it manually this time. the major areas are introduced to give you a quick overview of the way Qt works and how you can use it for your own purposes. you could argue that it would be easier to use the Qt Designer instead of manually creating the necessary source code. we will take a look behind the scenes and develop the UI manually.1 Hello World In the previous chapter. you will often have to modify or extend existing components to suit the exact needs of your application. To understand how the multi-platform build chain works.3 Qt in General Andreas Jakl One of the major reasons for the success of Qt is that it is designed to be cross-platform. almost no in-depth knowledge is required about the specific platforms you want to target. 1 2 3 4 5 6 7 #include <QApplication> #include <QLabel> int main(int argc. this chapter will introduce you to the general principles behind Qt. While this argument is valid in many situations. Additionally. char *argv[]) { QApplication app(argc. Carbide. getting it on different platforms is just a matter of recompiling. Now. Therefore. . While not providing detailed in-depth explanations of every concept.1 for a screenshot on Windows 7 and Symbian.cpp in an empty directory called HelloWorld. you will use Qt Creator. Of course. QLabel label("Hello World!"). Visual Studio or another IDE to create and manage your Qt projects. As a first step. you saw how to use the Qt Designer to create a user interface quickly. First. When working with the Symbian toolchain. 3. Usually.
it will appear on the screen. 8 9 10 label. As you can see by quickly scanning the source code. Conveniently.1. In the last source code line. It takes care of managing application-wide resources and handles the main event loop. QApplication and QLabel. If the user closes the application window.show().1 The Hello World application. The application enters its event loop and waits for user actions like mouse clicks. we create a QLabel object with the text 'Hello World!' In Qt terms. 3. a visual element of the user interface. the QApplication object is created. the corresponding header files have been given exactly the same name.exec(). it is automatically embedded in a window on the operating system's desktop. Next. touch events or keyboard presses. By calling its show() method. featuring a label with the famous piece of text. Afterwards. return app. As the label has no parent widget. the exec() function passes control to Qt. we use two classes. the exec() call returns and the application terminates. as Qt also supports some command-line arguments of its own. The command-line parameters are passed to the constructor.30 Qt for Symbian (a) Windows 7 (b) Symbian Figure 3. it is invisible. Initially. } The first two lines include the required header files for our application. this is called a widget.1 Building Now it is time to try the application. go to the directory where you have created your project and type: . Open a command prompt.
If you get an error message. # Input SOURCES += main. which contains information about the type of application to create (app or lib). If you add the parameter debug.pro file should look like this: 1 2 3 4 5 6 7 TEMPLATE = app TARGET = DEPENDPATH += .2 Packaging In Windows. and then copy the executable file into protected directories where hardly any other component has read/write access. Due to the security model on Symbian phones. . Alternatively. main.cpp Typing the following creates the platform-specific makefile from the project file.sis file.c++ for on-device debugging on Symbian phones. To package the application and to install it on your phone. The -i parameter automatically installs it on the phone afterwards. Follow the installation process on your phone to complete the installation.sis file to your phone via Bluetooth or a USB connection to install it manually. different files will be created. Instead. it accordingly creates a debug version.cpp) and other settings.exe file and enjoy your 'Hello World' application. first connect your phone to the PC and start the PC Suite. you can use over-the-air delivery or simply send the .pro).Qt in General 31 qmake -project This command generates a platform-independent project file (HelloWorld. you can now directly start the . INCLUDEPATH += . By default. the included source and header files (here. so that it can check the validity of the certificate plus the requested permissions. the system's installer component has to install all applications. Use Carbide. make creates a release version. On Symbian OS.exe files.mmp): qmake The next step is to start the compiler for your current target platform.pkg This will package the executable and the generated resources files for the phone menu into an installable and self-signed . make sure the path to the /bin/ folder of your Qt installation is part of the PATH system environment variable. If you are using the Symbian SDK. you can no longer directly start . make 3. Then type: createpackage -i HelloWorld_gcce_urel. The . there is one more step to go. this includes the resource file needed to show the application on the phone's menu and a Symbian-specific project file (.1. Depending on the target platform.
2 Basics A good way to start learning Qt is to work through an example. which automatically align and resize the widgets they are in charge of. layout->addWidget(slider). Initially. QPushButton* exitButton = new QPushButton("Exit"). an application user interface is made of multiple widgets that are arranged on the screen according to some rules. return app. char *argv[]) { QApplication app(argc. it was made full screen on the Symbian device. applications typically have to adapt to the new screen orientation and scale the user interface on-the-fly. argv).show(). for the platforms Windows 7 and Symbian: 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 #include #include #include #include <QApplication> <QVBoxLayout> <QSpinBox> <QSlider> int main(int argc. most mobile phones support screen rotation (e.2. The following example demonstrates the use of a vertical layout manager for three widgets – the resulting window is shown in Figure 3. Afterwards. QSlider* slider = new QSlider(Qt::Horizontal). A simple application on a desktop PC might very well have a fixed size that cannot be changed by the user – think of the simple calculator that comes with Windows. layout->addWidget(exitButton). the example is further expanded with a communication concept that dynamically connects multiple class instances. In Qt. Consult the Qt documentation for a visual overview of the available layout managers.32 Qt for Symbian 3.2. 3. QVBoxLayout* layout = new QVBoxLayout(&window). QWidget window. In most situations. it demonstrates how to define the layout for multiple widgets and then deals with questions about memory management. Managed layouts are especially important on mobile devices. On the other hand.1 Layouts The previous section demonstrated the use of a single widget (called control in Symbian) as a window itself – essentially. window. this is done through various types of layout managers.exec(). using acceleration sensors). QSpinBox* spinBox = new QSpinBox. layout->addWidget(spinBox).g. } . To maintain usability.
The three widgets (spinBox. a slider and an exit button and using a vertical layout manager. This time. Both are added to the QVBoxLayout. (b) Same application on Symbian. the layout manager is created. . The most obvious additions are three widgets – a slider.2). the three widgets automatically become visible when the parent object is shown on the screen.Qt in General 33 (a) Windows 7 (b) Symbian Figure 3. For developers with previous experience in UIQ3. the widget is turned into a window of its own through the show() method. it is also possible to define the behaviour of widgets in more detail: for example. no argument is supplied – this turns the object into the root of an object hierarchy (see Section 3. slider and exitButton) are constructed similarly to the label object in the first example. a simple QWidget class instance called window is created. When it is constructed. developers have manually to set positions and dimensions of all controls because no layout managers are available. the layout manager automatically makes sure that the widgets adapt to the available space. Next.2 A widget containing a spinbox. QWidget is often use as a container for other widgets or sub-classed to create its own widgets. In the previous section. If developing native C++ code for Symbian. Of course. At the end of the main() method. If we resize the window.2. layout managers will be familiar. we directly used the label widget as a window. No extra calls of the show() method are necessary. which is going to manage those objects. The QWidget object is passed as an argument in the constructor to inform the QVBoxLayout that it is responsible for the layout of window. (a) Application running on Windows 7. if you want the push button to stay sleek and small instead of occupying a large area of the screen. As children of the window object. a spinbox and a push button – which are now arranged by the layout manager (QVBoxLayout).
3 for the resulting object tree.2. While the source code suggests that the user interface widgets are children of the layout manager instance. window is used as the parent object and the four other objects are its children – see Figure 3.exec(). the memory allocated for the object is automatically released.3 Classes inherited from QObject can be stored in a tree structure.g. calling the exec() method of the QApplication object in the last line of the small application starts the event loop. the objects have to lie on the heap – which is why they were created using new. All of the classes we have been using in the example are ultimately derived from the QObject base class. If we were not to call a. Even though we did not set up any event handlers. Only the parent object should be created on the stack. you might wonder why the previous example did not delete the allocated objects. keyboard or touchscreen events) and will forward them to the appropriate class in our application. thus exiting it. The reason is that Qt takes over some of the memory management. Of course. However. but instead return 0. One of the resulting advantages is that QObject can store object hierarchies. the other objects are created on the heap and not explicitly deleted by our application. In our example. slider. For this to work. Qt automatically assigns the widget that owns the layout manager as the parent of the child . As mentioned when discussing the 'Hello World' example (see Section 3. The QObject base class provides various methods to query or change the object tree manually. In our case. the button labelled 'Exit' does not yet have any functionality. When it goes out of scope at the end of the main() method.34 Qt for Symbian Figure 3. the window object deletes the other objects (layout manager.2 Object Ownership and Memory Management Especially if your background is in mobile development. 3. the quit() method of QApplication is automatically called when the user closes the application through the red X in Windows or the red button on a phone. the application would terminate immediately without becoming visible on the screen. The window object is created on the stack using QWidget window.1). it automatically deletes its children as well. spinbox and the button) when it goes out of scope at the end of the main() method and is itself destroyed. Finally. When the parent object is deleted. it will wait for application events (e.
The most important of these is the concept of 'signals and slots' for flexible but safe communication between objects. Flexibility is a big advantage of this scheme. &app. The pointer to this instance is then sent to the external service provider (music player library). which we have just introduced for handling object hierarchies. SIGNAL(clicked()). Whenever a signal is emitted. Most toolkits use call-back functions or event listeners for informing other parts of an application about events or status updates.Qt in General 35 widgets. A slot is a normal C++ method that matches the signature (parameters) of the signal and that will now be called whenever the signal is emitted. we extend the example from the previous section and add interactivity.4).1 Basic Signals To demonstrate the use of signals and slots.3. The first two arguments of connect() specify the sender of the signal: the emitting class instance and the specific signal that should be bound to a slot. As the connect() method expects addresses of the objects. The first step equips the 'Exit' button with the expected functionality of closing the application. The QObject base class. it is time to take a look behind the scenes to understand how to make the application interactive. defines additional functionality and metaphors. Additionally. see the Qt . Whenever a specific event occurs – in this case when the button has been clicked – the button object emits a signal. there are many predefined slots in Qt widgets. it is possible to nest layouts. However. The last two arguments identify the receiving object as well as the slot (method) that should be executed in response to the signal. the sender has to store and manage pointers to each registered callback listener and has to check manually if the listener still exists before executing the call-back. the reference operator (&) is not necessary for the exitButton. but you can also add additional slots by sub-classing from Qt classes. each slot can receive signals from multiple source objects. Again. Qt widgets have many predefined signals.3 Signals and Slots After our first steps with the visuals. These drawbacks are addressed by the signals and slots concept of Qt. type safety is not checked by C++ for parameters. which should be added after the button has been created: QObject::connect(exitButton. 3. 3. developing an audio player in Symbian OS usually involves deriving a class from an interface. but you can also add your own signals. but no layout. which uses call-backs when the file is loaded or when playback has finished. The call to QObject::connect() creates a connection between the signal and the slot of another object (see Figure 3. all connected slots are called one after another in arbitrary order (multi-threaded variants are available. A signal can be connected to multiple slots. This is because a widget can only have another widget as a parent. This concept has several disadvantages – the listening class needs to implement a specific interface. SLOT(quit())). including QObject. This is accomplished with the following additional line of code. which is already a pointer. For example. when storing function pointers.
3. SIGNAL(valueChanged(int)). Qt delivers signals to objects interested in these events and calls the connected slots. SLOT(setValue(int))). nothing happens. SIGNAL(valueChanged(int)). These have to comply with Qt internal standards and dynamically reference the corresponding slots. the receiving widget needs to be informed of the new value whenever the other widget is modified. slots need not be concerned with where the signal originates. slider. documentation). this widget emits a valueChanged(int) signal. QObject::connect(spinBox. it is not possible to connect signals with incompatible slots.2 Parameters In many cases. These characteristics are vital for information encapsulation and ease development of independent modules that can be dynamically connected at runtime. The emitter does not know or need to know if anyone in the system is currently waiting for its signals. we do not need to be concerned about this. These are necessary because Qt expects string values to be passed to the function. Obviously. Because of the connect() statement. spinBox. but no matching link to a slot has been established. the setValue(int) slot of the spinBox is then immediately executed. On the other hand.4 Signals are emitted by an object whenever an interesting event occurs. The same thing happens in the reverse direction whenever the value .36 Qt for Symbian Figure 3. In the connect() call. Our example contains a spinbox and a slider widget. What if we want to synchronize those widgets? Changing the value in the spinbox should also update the slider widget and vice versa.3. If a signal is emitted. both the signal and slot are enclosed by the macros SIGNAL() and SLOT(). The macros ensure that these strings are generated correctly based on the specified method names. which becomes relevant when you want to pass parameters. Only two additional connect() statements are necessary to achieve this: QObject::connect(slider. A visible advantage is that Qt can check when establishing the connection at runtime if the signatures are compatible – thus. Whenever the user changes the value of the slider. additional information about the event has to be transmitted with the signal. SLOT(setValue(int))).
2) • Signals and slots • Properties and meta-information. 3. however. a warning will be issued to the terminal window when the connect() statement is executed and fails. however.4 Qt Object Model Qt extends the functionality of C++ classes to provide more flexibility while still preserving the efficiency of plain C++. 3.2. This is prevented by the implementation of setValue(int). this connection in both directions would lead to an infinite 'dialog' between both widgets.1 QObject The QObject class is at the heart of the Qt object model. if the slot of an own Internet transmission class only offers a slot that accepts values as strings. imagine that the calculation takes a long time or the result needs to be fetched from a web service. the int keyword indicates the integer argument that is transmitted to the slot and which specifies the new value. broadcasting the finished result of the operation through a custom signal is indeed useful. or if the signatures of the signal and the slot do not match. connect() returns a Boolean value that indicates if the connection was successfully established. Of course. The Qt object model mainly offers the following benefits. which only emits a valueChanged(int) signal when the new value is actually different from the previous one. it has to be derived from QObject and use the Q_OBJECT macro in its definition in the header file. you would not implement a simple calculation like this with signals and slots in a real-life scenario. you cannot directly connect the signal from the slider that transmits an int parameter. In both cases. multiplies it by 2 and emits the result through a signal. . Now that we have seen how to connect two existing classes. A failed connection can occur if either the sender or receiver does not exist. For a class to take advantage of the additional functionality.Qt in General 37 of slider is changed. when using a different signal of the spinbox: QObject::connect: Incompatible sender/receiver arguments QSpinBox::valueChanged(QString) --> QSlider::setValue(int) Therefore. which we will examine in the sections below in more detail: • Support with memory management (see Section 3. In these cases. Neither the compiler nor the linker will notice this. signals and slots are type safe. Note that the argument types are not automatically cast by Qt.g. the next step is to create your own signals and slots for communicating between different classes in your applications. Obviously. where the slider and the spinbox send updated values back and forth. e. For example. The following example demonstrates a custom class called SimpleMultiplier that receives a value through a slot.4.
If defined. public slots: void startCalculation(const QString value). signals: void resultReady(int result). Within a single class.) as well as the last line of the header file are common in C++. it therefore has to be derived from QObject. mingw32-make[1]: *** [debug/moc_simplemultiplier. it is usually sufficient to use direct function calls. They are used to avoid problems that could otherwise occur if multiple files in a larger project include the same header file. The Q_OBJECT macro is inserted right at the beginning of the class declaration. it is possible to specify a parent object. resulting in the class not having a parent. depending on the access requirements. This macro defines several functions that are required for the Qt object model.38 Qt for Symbian 3. The accessibility is set to public to make them accessible from outside the class – it would also be possible to use the protected or private access levels. it is not a widget: 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 #ifndef SIMPLEMULTIPLIER_H #define SIMPLEMULTIPLIER_H #include <QObject> class SimpleMultiplier : public QObject { Q_OBJECT public: SimpleMultiplier(QObject* = 0). Signals are always public to make communication between different classes useful. resulting in a redefinition of a class that is already known to the compiler. In contrast to the slots.2 Custom Signals and Slots Our new SimpleMultiplier class is using signals and slots.cpp] Error 1 Through the SimpleMultiplier constructor. this object will get the parent in an object hierarchy through its QObject base class. Signals can never have return values. therefore they always use void. .. If you forget to add the macro. }.. the signals: designator does not need an access control mode. the default value of 0 leads to a zero pointer. Otherwise. As described above. The next block in the class declaration contains the definition of the single custom slot that is offered by SimpleMultiplier instances.h:16: Error: Class declarations lacks Q_OBJECT macro. As the class does not display anything on the screen. #endif // SIMPLEMULTIPLIER_H The include guards in the first two (#ifdef .4. this will usually be noticed during the build process: simplemultiplier.
.4 Meta-object Compiler (moc) The extended concepts provided by the Qt meta-object model are not defined in C++. the argument is first converted to an integer through QString (see Section 3. 3.5. the source code is extended by the meta-object compiler tool called moc before being submitted to a standard compiler. Sending Qt-style source code directly to a standard C++ compiler would not work – for example. if (ok) { emit resultReady(num * 2).h" SimpleMultiplier::SimpleMultiplier(QObject* parent) : QObject(parent) {} void SimpleMultiplier::startCalculation(const QString value) { bool ok. If the conversion is successful. the signals: and slots: designators in the header files would not be recognized and result in an error. However. Indeed. It converts signals and slot constructs to standard C++ by generating additional source code.1). The argument of the slot is a const QString.5. the signal is only defined in the header file but not implemented in the . because of the public slots: designator in the header file. Qt opted for the second alternative to maintain the flexibility of Qt and to ensure that the Qt code works with every C++ compiler on all supported platforms. Two solutions are possible: using a custom C++ compiler.1. int num = value.4. } } The constructor passes the pointer of the parent object (or 0) to the QObject base class. without the use of signals and slots. due to Qt employing implicit sharing – see Section 3. it is additionally available as a slot. In contrast to the slot. Using call-by-value instead of passing a reference to the string does not generate the overhead you would expect. In the method implementation. it is a normal method that you can also call directly from your source code.Qt in General 39 3. Notice that the slot startCalculation(QString) is implemented as a normal C++ method.3 Implementing Slots and Emitting Signals The implementation of the SimpleMultiplier class described in the previous section is simple and short: 1 2 3 4 5 6 7 8 9 10 11 12 13 14 #include "simplemultiplier.4. Qt automatically adds the code to make the signal work through the meta-object compiler. the result of the multiplication by 2 is emitted as a signal. so that the slot can directly process the output of a standard QLineEdit widget. However. Therefore. or creating a tool that automatically rewrites the source code.cpp file.toInt(&ok).
If qmake is used to create the makefiles (as done by Qt Creator and Carbide. } After the construction of the QLineEdit object. the main() method creates a widget called window which contains two predefined Qt widgets: a text box (QLineEdit) and a label (QLabel) – see Figure 3.2.4. QLineEdit* input = new QLineEdit(). QIntValidator* validateRange = new QIntValidator(0. argv). The include statements are omitted in the following source code.1. 3. SLOT(startCalculation(QString))). the process works without problems.5 Connecting Signals and Slots To demonstrate the use of the SimpleMultiplier class defined in Section 3. QLabel* result = new QLabel(). The same article also lists reasons why C++ templates were not suitable for this task. a validator is assigned to it. return app. QObject::connect(&mult.4. QObject::connect(input. Validators can restrict the input of an editor widget. we use a minimal user interface. result. Similar to the first example from Section 3. SLOT(setNum(int))). &mult. window. layout->addWidget(input). input). SimpleMultiplier mult. moc creates additional files that are included in the build process (moc_myclass.cpp). SIGNAL(textEdited(QString)).2. char *argv[]) { QApplication app(argc. the required header file names correspond to the class names used in the example: 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 int main(int argc. This time. QHBoxLayout* layout = new QHBoxLayout(&window).40 Qt for Symbian your own source files are never modified – instead.c++). SIGNAL(resultReady(int)). In this case.exec(). a horizontal layout manager (QHBoxLayout) is responsible for distributing the available space of the window to the widgets. This is done for all classes that include the Q_OBJECT macro. layout->addWidget(result).5. A few limitations are listed in the official Qt documentation (accessible through the help in Qt Creator) under the topic 'Using the Meta-Object Compiler (moc)'.show(). 255. a predefined integer validator (QIntValidator) . In general. QWidget window. build rules that call moc when required are included automatically. input->setValidator(validateRange).
Own validators can easily be developed. whose first two parameters specify the minimum and maximum value respectively.6 The calculation of the custom SimpleMultiplier class is triggered by the startCalculation(QString) slot. With the second connection. the result of the calculation is relayed to the label widget. As already described in Section 3. Through these two connections.Qt in General 41 Figure 3. If you wanted to display the result in a second label or transmit it over the Internet. Figure 3.3. Because of this. no automatic type conversion is performed. Two signals and slots connections are responsible for responding to the user typing into the text box (see Figure 3.5 A custom class multiplies the input received through a custom slot by 2 and emits the result through a signal. it publishes the results through the resultReady(int) signal. the use of regular expressions is possible as well.2. we use a QString parameter for the startCalculation() slot. is used. you would simply create another connection that binds the signal to a second slot. .6). Afterwards. The beauty of this solution lies in its flexibility. The first connects the textEdited signal emitted by the QLineEdit widget whenever its contents are modified with the startCalculation(QString) slot of our own SimpleMultiplier class instance. the result is always updated as soon as the user types in the line edit widget. as this is the same as the parameter emitted by the textEdited() signal.
Of course. This concept is extensively used for the user interface components. // Print name and value to debug out const char *name = metaproperty. which stores text on the heap in Unicode format. value:" << value. for (int i=0. its super-class or the available meta-methods (signals. The following code discovers and queries the properties of a standard QPushButton instance named but: 1 2 3 4 5 6 7 8 9 10 11 12 13 QPushButton but("Hello Property"). // Get meta object of target object const QMetaObject *metaobject = but. qDebug() << "Name:" << name << ". QVariant value = but. These range from layout parameters like the position and size.1 Handling Text through Implicit Sharing Almost every application requires text in some form. However. the main difference being that these can not only be declared in the class header file (through a specific Q_PROPERTY() macro). A prime example is QString. but even be added dynamically at runtime. That is only a tiny part of the truth. 3. They can be added to classes or class instances and behave like member variables. It can be compared with the new LString class or the RBuf descriptor . it can be useful for meta-applications like scripting engines. UI classes especially are usually derived from QObject as described in the previous sections.6 Properties and Meta-information Properties are another Qt extension to the standard C++ object system. up to the locale being used.5. As a result. Therefore. we will take a look at some of those. the QMetaObject instance created for each QObject sub-class provides information about the class name of your object. many other classes do not require signals. ++i) { // Retrieve current property QMetaProperty metaproperty = metaobject->property(i). so we will start with that. as Qt is much more than this and provides many other helpful services and modules to application developers. } The result will be 71 defined properties. In later sections. they are not derived from QObject. i<count. While this is usually not required for standard application development. slots or automatic memory management. the UI is still an essential part of almost all Qt applications. Additionally.4.name(). through visibility and button text.5 User Interface Qt is often considered as a UI toolkit that allows the creation of a UI that works on multiple platforms. // Number of properties int count = metaobject->propertyCount(). 3.42 Qt for Symbian 3.property(name). like network or XML support (see Section 3. we first take an in-depth look at how to work with text and strings.metaObject(). slots).7).
As a result.Qt in General 43 Figure 3. in Symbian OS. Different language variants can then easily be created by including the corresponding file. it automatically converts the const char* data to Unicode in the following scenario: QString str1 = "Hello world". After executing this short segment of code. Users commonly expect localized content on their mobile device. This is exactly what you would expect and all that you usually need to care about. only the pointer is passed and both variables still reference the same text buffer on the heap (shallow copy). whereas str2 now reads 'Hello Qt'. whereas usually only the one corresponding . Additionally. str2. This happens behind the scenes. As a result. during initialization. str1 will still contain its original 'Hello world' text. Especially when working on mobile devices where memory is limited. Using the QSharedDataPointer class. For the UI.sis installation file. Only when the contents of str2 are modified does Qt have to make both strings separate in memory and perform a deep copy.g. QString comes with plenty of overloads and functions. it is usually vital for mobile applications. QString str2 = str1. (atomic) reference counting is used for the data. 3. it is therefore usually not necessary to pass pointers to strings for parameters.7 For QString objects. All strings are externalized to an additional file.2 Internationalization While internationalization might not be important for your first steps with desktop applications.replace("world". you can easily use implicit sharing for your own classes. Qt does not copy it right away (see Figure 3. "Qt"). While the second line of the code above actually assigns the value of str1 to str2. Instead. C++ resource files are used. The same mechanism is also employed by other classes. All localized resource files are shipped with the .7). the QImage class for loading and saving images. without intervention from you as a developer. it is interesting to know that Qt automatically applies the concept of implicit sharing. both the speed and memory usage are optimized. as call-by-value does not actually copy the contents of the string. native C++ applications for Symbian OS tightly integrate internationalization. making it easy to use. To make this mechanism safe.5. For example. e. data is automatically only copied when needed (implicit sharing).
Take a look at the help section of Qt Creator for instructions on how to handle those situations. The following example demonstrates the initialization of a label widget with localizable text: QLabel* label = new QLabel(tr("Hello World")). you can provide a textual description of the situation.pro-filename>. further calls to the same tool will update the existing . in this case for German and French: TRANSLATIONS = demo_de. the QObject base class enables easy integration of translated text even in special cases (e.ts – translation source). but instead to embed the default language directly into the code (usually English) and if necessary to replace the text through external translation files at runtime. maintaining at the same time the advantages of having extra translation files. The only remaining task is to load the translation files accordingly. which can easily be used by external translators without technical proficiency.ts files. run lrelease <. After all strings have been translated and are marked as 'finished'. Only if your application does not include the required language will the user get the choice of which other language is preferred.qm files out of the XML-based . It parses all files registered in the project file under SOURCES.ts files. it might have to be placed at a different position for different languages. whereas the resource file approach of Symbian OS mostly requires manual solutions. translation is often not this straightforward. HEADERS and FORMS and generates the .. The aim is not to kick all text out of the source code.ts files. which you can ship with your applications or embed into the executable file. Text written in the source code is the default language. which will then be visible only to the translator. a method provided by QObject. all you need to do is to enclose the string in the source code with tr(). If you add additional text later on. The word order of languages especially has an effect on dynamic text – when inserting for example a file name into a status message. The process of translating text is different in Qt. which are based on an XML format. depending on their value. Of course. In the application source code.ts files. Add any additional translations to the project file.g. the QTranslator class is initialized at the beginning of the main() method: . Additionally. numbers might require different text for singular and plural.ts To extract all translatable strings from your source code and to generate the translation files (. plurals). This application provides a convenient UI for the translation process. Specific Qt tools help with generating and working with these files. This makes the code easier to write.ts \ demo_fr. Additionally.profilename>. The tool generates compact binary . Translating Text For basic translation. Usually.44 Qt for Symbian to the current phone language is installed. call the tool lupdate <. a more convenient way is to use Qt Linguist. The tool also provides a preview (if Qt Designer was used for generating the UI) and validation features. utility classes like StringLoader are responsible for loading text from resource files into memory (descriptors). If the context is relevant for correct translation. While it is possible to work directly on the .
which is returned as a string consisting of a language code and a country code (e.g. If a suitable file has been found. Of course.name()). Dialogs and the Main Window When developing bigger applications.toLower(). Qt will automatically try to find more generic versions of the translation file. These include sub-classing widgets.arg(QLocale::system(). // Load the correct translation file (if available) QTranslator translator. QTranslator first tries to load the specific translation file. Sub-classing Widgets A common approach for creating a UI is to derive a custom class from the generic QWidget base class.8). translator. as member variables and create them in the constructor. etc. which also happens to be a widget.Qt in General 45 Figure 3. it will go through more generic variants step by step to find a suitable translation (see Figure 3. For example. buttons. add individual UI widgets like labels. the class would automatically load the de file if you did not provide specific translations for Austria (de_AT) or Switzerland (de_CH).load(filename. the work is done and your application is translated.installTranslator(&translator). The first line retrieves the current system locale. dialogs or using the main window. Qt offers more flexible and powerful approaches.. That way. Modifications or additions do not influence the rest of the . qApp->applicationDirPath()). Adding additional languages is just a matter of creating more translation files and adding them to the project file. de_AT for Austrian German). the approach of simply creating various widgets in the main() method will soon reveal its limits. // Adds the loaded file to list of active translation files app. 3. if you only provided a generic German translation.8 If needed. If this is not available.5. Next. 1 2 3 4 5 6 7 // Get locale of the system QString filename = QString("demo_%1"). UI elements that belong together are encapsulated in a single class.3 Widgets.
. which are controls themselves. Qt already comes with different predefined dialogs.46 Qt for Symbian (a) Windows 7 (b) Symbian Figure 3. This can be compared with the containers in the traditional Symbian architecture. (b) Same application on Symbian. it is common to sub-class QDialog. and many others. for entering text or numbers. the resulting choice being reflected in the integer return value: int ret = QMessageBox::warning( this. Two options are offered. Using predefined dialogs is easy. a file or a font. but only serve to manage sub-controls that are the visible UI elements. "Exit?". QMessageBox::Yes | QMessageBox::No ). asking if the user really wants to exit (see Figure 3. The box shows a warning message. Similar to widgets. These are intended to be used for in-between information. "Do you really want to exit the application?". Dialogs In addition to sub-classing widgets.g. the basic concept is the same – the QDialog class just adds additional methods that are useful for dialogs.9). (a) Application running on Windows 7. The following code demonstrates this using a simple message box. like asking the user if an Internet connection is to be established (yes/no). application. which is fundamental for most applications. e. the whole application is usually not terminated. it is also possible to use dialogs.9 Predefined dialogs for common usage scenarios are provided by Qt – this example shows the warning dialog. selecting a colour. If a dialog window is closed. Therefore. which is itself derived from QWidget.
They wait for the user to interact in order to start working on the requested task.7.3 for an example.Qt in General 47 Figure 3. menu commands are automatically mapped to the Options menu of the left softkey on Symbian. the parent is blocked until the dialog returns – interaction is only possible with the dialog as long as it is possible. you can also create non-modal dialogs.10). . using the main window is more comfortable and ensures a consistent appearance across multiple platforms. which already defines several components that standard UI applications commonly need. Additionally. for a search dialog in a text editor application. Compared with continuously polling for status changes ('is the user currently pressing a button?'). The central widget represents the main window content (= the workspace for the user).10 The standard layout of a main window on a desktop platform. See Section 3. 3. sending events to a sleeping application saves a considerable amount of processing time and thus battery life. Of course. To create your own main window. By default. This means that the dialog window is always in front of the parent window. This section takes a look at how to work with events and timers in Qt. derive it from the QMainWindow class. Of course.6 System Usually. however. this dialog is modal. This can be useful. a menu and a status bar (see Figure 3. but still allow interaction with the editor. the QMainWindow represents a predefined layout for the application window. UI-based applications are event based. For example. for example. Main Window Essentially. This includes toolbars. dock widgets. Such a dialog should stay in the foreground so that the user can search for the next word. creating a layout like that is also possible with dialogs and widgets.
Figure 3. fetches those events from the event queue.g. Through an event dispatcher. keyboard presses. the main event loop. The generic event() method then calls a specific event handling method suitable for this kind of event (mouseReleasedEvent()). Therefore. Up to now. when a window is shown for the first time). . Widgets like the QPushButton already include event handlers that emit corresponding signals in response to events. QCoreApplication::exec(). it is a QPushButton. etc.6.48 Qt for Symbian Figure 3. 3. First. The first event is concerned with native system window events.1 Events Events are generated in response to user actions (touch events. Event Delivery Events can be generated in two different ways. the hardware event is delivered to the event loop of QCoreApplication::exec(). events are mostly important when implementing a widget of your own or if you require to modify the behaviour of an existing Qt widget.) or by the system (e. the clicked() signal when an appropriate mouse or keyboard event is received. System events are then translated into QEvents and sent to relevant QObjects.11 shows a schematic overview of the relation between events and signals and slots through the example of a mouse release event being delivered to a button.g. you will not be in touch with events in this case. like queries to redraw the screen. Usually. e. we have only been concerned with using predefined widgets. Signals on the other hand are important when using a widget or for internal communication within your own application. the QEvent is then sent to the virtual event() method of the appropriate QObject – in this case. This also leads to a clicked() signal that is emitted by the QPushButton. The signal is finally delivered to your own custom slot that starts the appropriate action for the mouse click on the button.11 This diagram demonstrates in a simplified way how an actual hardware event is translated into a QEvent and then a signal that is handled by your own custom slot.
For more control. It is mainly used to perform processing at regular intervals. with the QEvent object as parameter. 3. These events are then processed by the same event loop. Blinking cursors or other animations are good examples of the use of the timer. In this method. To support low-level drawing. the following example draws a slowly rotating square (see Figure 3.6. This example directly creates an object of type QTimer. which is triggered after a specific time has passed. Our class is a widget and thus also indirectly derived from QObject. like the mouse cursor position or the area to redraw. Regular call-backs of the timer cause the graphics to redraw.Qt in General 49 Secondly. In contrast to a user-generated mouse button click as in the scenario described earlier. the code is omitted here. you do not have to write your own event handler function for taking care of common events – you only need to override the corresponding predefined handler method from the QWidget base class. A timer can be started in multiple ways. this event is generated by Qt itself. protected: . This results in regular subsequent calls to paintEvent(). it might be propagated to its parent). Due to the object hierarchy. Therefore. the class usually examines the event and decides whether to handle or to ignore it – therefore. this method can be referred to as event handler. The QTimerEvent is an example of a self-generated event. events are distributed automatically and you do not have to register explicitly for events in standard usage scenarios. Specific sub-classes like QMouseEvent or QPaintEvent extend the QEvent class to store specific information. The QCoreApplication dispatches events to the event() method of the target QObject. The basic QEvent only stores the event type plus a flag where a receiving QObject can indicate if it accepted this event (otherwise. The main() method simply creates an instance of the custom RotateWidget class and calls show() on it. However.12).2 Timers and Painting Among the most common events are timer events. Then. before using QCoreApplication::exec() to start the event loop. a QEvent can also be generated by Qt itself. The rotation angle of the quad depends on the current system time. The implementation of event() in the QWidget class distributes common events to specific handler methods like mouseMoveEvent() or paintEvent(). you can write custom event filters and register for events of other QObjects. The method is an event handler that is called in response to paint events: 1 2 3 4 5 6 class RotateWidget : public QWidget { public: RotateWidget(QWidget* parent = 0). the full source code is available online. As this is similar to the previous examples. it connects its timeout() signal to the update() slot of the widget. Support for timers is built into the QObject base class. To introduce timers as well as repaint events and the basics of low-level painting. The header file of the RotateWidget class is short and simple. which is in turn called as part of the widget redraw process. which is required for event and timer support. it overrides the paintEvent(QPaintEvent*) method from the QWidget base class.
Only redrawing a certain region .50 Qt for Symbian Figure 3. The constructor of the RotateWidget class first creates a new timer. It turns the timer into a child of the widget. Most importantly. The quad rotates with the speed of the clock. Qt automatically takes care of double buffering the output. The supplied parameter specifies the parent of the timer (this). connect(timer. } The paintEvent() method is called in response to paint events. thus preventing flickering. The parameter of type QPaintEvent contains event parameters for paint events. it contains the region that needs to be updated. As specified above. timer->start(50). SLOT(update())). so that it will be deleted when the parent RotateWidget is deleted: 1 2 3 4 5 6 7 8 9 10 RotateWidget::RotateWidget(QWidget* parent) : QWidget(parent) { QTimer* timer = new QTimer(this). resize(360. this. 7 8 void paintEvent(QPaintEvent* event). This means that the changes caused by the individual drawing operations are only copied to the screen when the paintEvent() method is finished. }. 360).12 A screenshot of the timer example. which can occur if repaint() or update() is invoked on the widget (as in our case) or if the widget was obscured and is now uncovered. SIGNAL(timeout()). this example demonstrates the creation of an instance of the QTimer object. setWindowTitle(tr("Rotating Quad")).
Also. like bitmaps or a printer. especially on mobile platforms. painter. 3.Qt in General 51 instead of the whole widget can lead to significant performance improvements.0)) * 6. no direct connections to the slot can be made with the startTimer() method.12 shows a screenshot of this application running on Symbian. Next. which results in less jagged edges of the rectangle due to the use of transparencies. 0.drawRect(QRect(-50. This method returns an ID. Figure 3.0). The brush defines the fill colour and pattern of an object. height() / 2). In contrast to using a dedicated QTimer object. When you execute the application. it is easier to redraw the whole widget contents. -50. painter. painter. Qt features streamlined interfaces that simplify communicating over various 'devices' like sockets. First. Instead. which were not required in this example but are often useful. 100. only QTimer supports single-shot timers. 255). painter. we adapt the settings of QPainter. In the end.msec() / 1000. you should see the blue square slowly turning clockwise. the timerEvent() method of your class will be called at regular intervals. files or even processes. QTime time = QTime::currentTime(). a square with a size of 100 × 100 is drawn at the coordinates −50/−50.translate(width() / 2. in order to centre it around the origin of the translated (and rotated) coordinate system. The next three source code lines ensure the correct position and rotation of the square. which is used to identify and further control the timer. Next. QColor quadColor(0. communication is a vital aspect of almost every application. Not only is it easy to . In the next few lines of the source code. the coordinate system of the painter is translated to the centre of the available size of the widget. The first activated configuration is to prefer using anti-aliasing. painter. } In the paintEvent() method. it would be possible to start a timer using the startTimer() method of the QObject base class instead of using QTimer directly. Its rotation is directly related to the current seconds and milliseconds – it would be easy to extend the application to create a full analogue clock (see the Qt documentation for such an example). 100)). The parameter is therefore unused: 1 2 3 4 5 6 7 8 9 10 11 12 13 void RotateWidget::paintEvent(QPaintEvent*) { QPainter painter(this). whereas the pen defines the outline style. It offers many convenient methods for drawing simple or more complex shapes.second() + (time. In our case.rotate((time.7 Communication Especially on a mobile phone. a rotate command applies a rotation of the coordinate system depending on the current number of seconds. Much like Java ME with the Generic Connection Framework.setBrush(quadColor). This class is used to perform low-level painting on widgets or other paint devices. as well as text and pixmaps. the brush is configured to use a blue colour.setRenderHint(QPainter::Antialiasing). we first create a QPainter object. Alternatively.
Qt for Symbian
Figure 3.13 Class hierarchy of QIODevice and its sub-classes.
replace the employed device using a common base class, but also, when developing distributed or client/server applications, the same code can be used on the Symbian mobile phone as well as on the PC/server side with, for example, a Linux-based operating system.
3.7.1 Input/Output
Figure 3.13 illustrates the classes that inherit from the abstract base class QIODevice. These include various socket-related classes, QBuffer for reading from and writing to a QByteArray, file-related classes for accessing files in the local file system, embedded resources and temporary files, and finally QProcess for inter-process communication. Obviously, all these devices behave differently, so QIODevice implements the lowest common denominator of all input and output operations. The most important distinction that still remains is the way of reading data. Sockets and processes are sequential devices; data must be read in one pass. On the other hand, files and QBuffer are random access devices, which allow reading at arbitrary positions using seek(). Comparable with Java, Qt provides additional higher level stream classes that simplify reading and writing Qt data types to byte-based streams. QDataStream provides serialization of binary data and already includes implementations for C++'s basic data types as well as many Qt data types. By overloading the << and >> operators, you can add support for custom data types. For text-based data, the class QTextStream helps with reading and writing words, lines and numbers. These two stream classes take care of lower level necessities like byte ordering and text encoding and therefore help in developing international cross-platform applications.
3.7.2 Files and Streams
To demonstrate the use of files and data streams, we will use a console application without a GUI. In contrast to the previous examples, this type of application only requires QtCore. Adding the configuration console to the project file (.pro) enables console output on Windows. For Mac OS X, the project settings also tell qmake not to put the executable inside a bundle:
Qt in General
1 2 3 4 5
TEMPLATE = app QT = core CONFIG += console CONFIG -= app_bundle SOURCES += main.cpp
This application does not use a QCoreApplication object, as QFile does not need the event loop – our example is finished after sequentially working through the source code in main(). First, the example creates a file and then serializes three different variables. In the second part, these variables are read back in again:
1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26
#include #include #include #include
<QtCore> <QDebug> <iostream> <stdio.h>
int main(int argc, char* argv[]) { // Writing a file QFile outFile("data.dat"); if (!outFile.open(QIODevice::WriteOnly)) { std::cerr << "Cannot open file for writing: " << outFile.errorString().toStdString() << std::endl; return 1; } QDataStream out(&outFile); out.setVersion(QDataStream::Qt_4_5); quint32 outValue = 12345678; QTime outTime = QTime::currentTime(); QVariant outVar("Some text"); out << outValue << outTime << outVar; outFile.close(); // (continued in next listing)
At first, our application tries to open the file data.dat for writing. If this operation fails, an error message is printed. This is done using the standard error stream (std::cerr), which is by default directed to the console. The QString returned by outFile.errorString() needs to be converted to a std::string using toStdString(), for which <iostream> has a << overload. If the file was opened correctly, a QDataStream is constructed using the QFile object (based on QIODevice). In our example, the task of the stream class is to write three different variable types to the file using operator«(), which is overloaded to handle various data types. QDataStream's binary representation of objects has changed in the many years since Qt 1.0 was released, and will continue to do so in the future. In order to maintain forward and
Qt for Symbian
Figure 3.14 Properties of the QDataStream in the debug view of Qt Creator.
backward compatibility, it is helpful to hard-code the version number in the application (e.g. QDataStream::Qt_4_5). This ensures that the data is written and read in exactly the same way. Additionally, the data format is platform independent. You can transfer data via a network connection from an ARM-based mobile device to an Intel-based PC without problems. In Figure 3.14 you can see that Big Endian data encoding is used by default (see the byte-order property of the out class instance). The data format version of Qt_4_5 equals decimal 11. Especially for settings files, it is a good idea to extend the example to include a brief file header. This should contain a magic string that allows you to check if the file is really from your application. A version number helps to import correctly old versions of settings files if you decide to expand the file in future versions. See the documentation of QDataStream for an example.
Qt in General
The QVariant data type used for the third variable is a powerful data type. It acts like a union of the most common Qt data types. It stores one type of data and can additionally convert between different types. In our case, the QVariant contains a QString. In addition to serializing the actual content, QVariant additionally saves the type of the variable to the stream, so that it can be read back using a QVariant. As the outFile object was created on the stack, it will close the file automatically when the variable goes out of scope. However, to be on the safe side and to save resources, it is still a good idea to close resources as soon as you no longer need them. Reading the file back in works in a similar way to writing the data. After opening the file and creating a QDataStream, we set the stream version to ensure compatibility. Next, the three variables are read back in exactly the same order:
1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24
// Reading a file (continued from previous listing) QFile inFile("data.dat"); if (!inFile.open(QIODevice::ReadOnly)) { std::cerr << "Cannot open file for reading: " << inFile.errorString().toStdString() << std::endl; return 1; } QDataStream in(&inFile); in.setVersion(QDataStream::Qt_4_5); quint32 inValue; QTime inTime; QVariant inVar; // Read values in same order as they were written in >> inValue >> inTime >> inVar; qDebug() << "Variant type:" << inVar.typeName() << ", contents:" << inVar.toString(); inFile.close(); return 0; }
The variable inVar of type QVariant recognized the type that was previously written to the file. The debug output line prints the type of the variable (as text) and then returns the variant as a QString:
Variant type: QString , contents: "Some text"
Instead of using the standard streams provided by <iostream>, the qDebug() global function (available when including <QDebug>) is used as the output stream. By default, this prints the text to stderr output under Unix/X11 and Mac OS X and to the console (for console apps) or the debugger under Windows. An additional advantage is that Qt data types like QString can be directly serialized, without conversion to a std::string or char*.
Especially in the mobile context. take a look at the Fortune Server example from the Qt SDK. as well as for resolving host names and working with network proxies. As mentioned above. you can directly transmit byte arrays through the read() and write() methods of the socket.7. 3.3 Networking and XML While the QFile class is part of the QtCore package that is part of every Qt project. the bind() method of the QUdpSocket is used to bind a socket to the specified address and port. you can easily implement a server that creates individual threads to serve each incoming client. which is a metainclude that contains all the include files for the classes offered by the QtNetwork module. low-level TCP connections are often preferable to HTTP connections. Status changes and errors are emitted via signals.7. Another option is to derive from the class to customize the behaviour. You can use an instance of the QTcpSocket class in your application to handle the network communication. The operations are performed asynchronously. you can use the classes of QDataStream and QTextStream introduced earlier on a socket (see Section 3. Due to the nature of the connectionless UDP.2). Instead of working with higher level data types. using classes related to communication with the network requires the additional QtNetwork extension module. . Instead. as they involve less overhead and therefore result in less data to be transferred over often slow wireless connections. Usage is easy through the convenient QDataStream class. as we did before. TCP and UDP The stream-oriented TCP communication protocol is implemented by QTcpSocket. simply include the appropriate header files of the Qt classes in use. as demonstrated in this example. Insert the following declaration into your qmake project file: QT += network In the source code. The module provides classes that enable working with both the TCP and UDP protocols. If you prefer a lower level way of handling data. convenience classes for the higher level protocols HTTP (through the network manager) and FTP are included. where each one contains the target address as well as the data. Alternatively. no extra server class is required for implementing a UDP server. Apart from these differences. the QUdpSocket behaves mostly like its TCP counterpart. you can use the directive #include <QtNetwork>. To compare a simple single-threaded server with the more powerful multi-threaded variant. the QTextStream class is specialized on serializing text and can take care of different character encodings.56 Qt for Symbian You can store data in a very compact way using binary data formats. Transferring data is done through (usually smaller) datagrams. you can use the QIODevice's write() and readAll() functions directly without using higher level stream classes. Additionally. Depending on the expected number of simultaneously served clients. As QTcpSocket is indirectly derived from QIODevice. The QTcpServer class makes it possible to accept incoming TCP connections.
It is parsed by the QXmlStreamReader.google.com/intl/en/apis/maps/documentation/index.html. but instead directly provides the result of a query formatted in plain text. In Qt.org/TR/xquery/.15 for a screenshot of the example application. pull tokens from the reader one after another. Enter the name or address into the upper text box of a location that you want to look up. 2 http://code.58 Qt for Symbian Figure 3. Austria'.15 Through parsing the output of the Geocoding web service from Google Maps. as well as a point in the centre of this area. The main advantage is that it does not require manual procedural programming in C++. Austria</name> <Placemark id="p1"> <address> Fachhochschule Hagenberg. Clicking the 'Ok' button sends an HTTP request to the Geocoding web service.w3. the XQuery/XPath language is very suitable. 4232 Hagenberg im Mühlkreis. latitude and altitude (if available. Finally. the extracted coordinates of the placemark are converted to numeric values and shown in the second text box. this element is called <coordinates> and contains the longitude. This is comparable with an iterator with embedded intelligence specifically tailored for XML files. the Geocoding API will return the resulting XML which is shown below in a truncated version – the full XML file contains some additional details.2 See Figure 3. the example demonstrates the use of HTTP and XML parsing. the following example provides a UI for Google's Geocoding web service. When searching for the location 'FH Hagenberg. Example: Geocoding Web Service To demonstrate the use of the HTTP and XML APIs as well as the main window. 1 http://www. otherwise set to 0): 1 2 3 4 5 6 <kml> <Response> <name>FH Hagenberg. an implementation is provided in the QtXmlPatterns module. which contains the longitude and latitude. It is defined by the W3C1 to address the need for intelligently querying XML data sources. The Keyhole Markup Language (kml) data provides information about the full address of the placemark. the region that it occupies on the map. The response is encoded as an XML file. Especially for tasks that require searching and transforming XML files. .
or if you want to access more restricted areas of the phone (e.symbiansigned. accessing the network is only allowed if you specify in the project file that your application might require it (the capability is called NetworkServices).cpp file simply creates an instance of the UI class.4990745"/> </ExtendedData> <Point> <coordinates>14. Additionally. do not forget to add the capability to the project file to indicate that your application will want to use the network – if you forget to do so. In this concept.3760743" south="48. it is shown full screen (non-full-screen applications are not common on Symbian).CAPABILITY = NetworkServices Setup As usual. the standard self-signed certificate is sufficient if we can live with the security warning during installation on a Symbian device. informing the user what the application might do and that it does not originate from a trusted supplier. if you want to simulate key presses for the whole system).cpp QT += network xml symbian:TARGET.48. In a desktop environment. By default. connection attempts will fail at runtime: 1 2 3 4 5 HEADERS += xmldataview. This distinction is executed by a preprocessor directive.3686622. the self-signed certificate is no longer 'mighty' enough. the IDEs create a self-signed certificate on your PC when you first build an application.0</coordinates> </Point> </Placemark> </Response> </kml> As mentioned above. 3 http://www. See the Symbian Signed website3 for more details on how to use these capabilities for development and on how to obtain a trusted certificate for commercial release. the main.cpp \ main. you also have to take Platform Security into account.g. For example. a security warning will be shown during installation. For our web service example. If the application is executed on a Symbian OS device.3612490" east="14. the window is shown using the default size.h SOURCES += xmldataview. However. which is called XmlDataView in this example.Qt in General 59 7 8 9 10 11 12 13 14 15 16 17 18 Österreich </address> <ExtendedData> <LatLonBox north="48. using Qt's networking and XML classes requires adding the corresponding modules to the qmake project file.com/ .5310893" west="14.5150819. While this certificate is sufficient for using basic capabilities like network access. the certificate that is used to sign the packaged application has to be sufficient for the requested capabilities. For commercial distribution. When targeting the Symbian platform. access to certain security-relevant parts of the system is only allowed if the corresponding Capabilities are specified at compile-time.
. public slots: // Send the HTTP request to retrieve the resulting XML file void retrieveXml().60 Qt for Symbian 1 2 3 4 5 6 7 8 9 10 11 int main(int argc. } The class declaration reveals that XmlDataView is derived from QMainWindow. void parseXml(const QString &data).exec(). Two QLineEdit objects are stored as instance variables. as we will just connect its clicked() signal to the slot that starts the lookup process. QLineEdit* resultEdit. It is not required to keep a pointer to the 'Ok' button.2. #if defined(Q_OS_SYMBIAN) geoWindow. All three UI widgets are defined as children of the main window's central widget. #endif return app. private: // Private function that parses the XML returned from the web service. #else geoWindow. which contains the XML file void handleNetworkData(QNetworkReply *networkReply). which was described in Section 3. char* argv[]) { QApplication app(argc. as the application needs to interact with the text content. argv). // Parsed coordinates from the XML file QString coordinates. Our class provides two slots.2).showMaximized(). // Ui-Elements QLineEdit* locationEdit. private: QNetworkAccessManager networkManager. so they will be automatically deleted when the main window is deleted due to Qt's object hierarchy (see Section 3.show(). }.5.3: 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 class XmlDataView : public QMainWindow { Q_OBJECT public: XmlDataView(QWidget* parent = 0). which are executed in response to signals emitted by the UI and the network connection. // Handle the network response. XmlDataView geoWindow.
this. query. QPushButton* okButton = new QPushButton(tr("Ok")). Submitting the HTTP request Next up in the logical application structure is the slot called retrieveXml(): 1 2 3 4 5 6 7 8 9 void XmlDataView::retrieveXml() { QString query = locationEdit->text(). First. setCentralWidget(cw).addEncodedQueryItem("q". statusBar()->showMessage(tr("Welcome")). Instead of tracking the progress of individual requests we simply connect the finished() signal of the network manager to the handleNetworkData() slot. lay->addWidget(locationEdit).toUtf8()). connect(&networkManager. locationEdit = new QLineEdit(). it configures the UI. QWidget* cw = new QWidget(). SLOT(retrieveXml())). SIGNAL(finished(QNetworkReply*)). which stores the layout and the three UI elements and is then handed over to the main window through setCentralWidget(). QVBoxLayout* lay = new QVBoxLayout(cw).com/maps/geo"). url.google. let us take a look at the implementation of this class: 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 XmlDataView::XmlDataView(QWidget* parent) : QMainWindow(parent) { setWindowTitle(tr("Geocoder")). . lay->addWidget(okButton). this. connect(okButton. SLOT(handleNetworkData(QNetworkReply*))). SIGNAL(returnPressed()). The last part of the constructor deals with the signals and slots connections. lay->addWidget(resultEdit).replace(' '. QUrl url("http://maps. if (query. the signal will be executed when processing of the network request has finished. this. resultEdit = new QLineEdit(). connect(locationEdit. SLOT(retrieveXml())). The main window's status bar is used to inform the user of the current state. The first two connections ensure that both methods create a network request: clicking on the Ok button as well as pressing the Enter key while the locationEdit element has keyboard focus. SIGNAL(clicked()).Qt in General 61 Now. query. } The constructor contains relatively few surprises. As the name already implies.isEmpty()) return. A central widget of the basic type QWidget is used as the parent object. '+').
split('.count() == 3) { . coordinates.tokenType() == QXmlStreamReader::StartElement) { if (xml. QStringList l = coordinates. "abcdefg").'). The method returns immediately and the request is queued and executed asynchronously in Qt's event loop. This will happen as soon as the control returns to the event loop: 1 2 3 4 5 6 7 8 9 10 11 12 13 void XmlDataView::parseXml(const QString &data) { QXmlStreamReader xml(data). if (l.atEnd()) { xml. calling deleteLater() schedules the object for deletion.62 Qt for Symbian 10 11 12 13 14 15 16 url.addEncodedQueryItem("sensor". if (xml. Parsing the XML response As soon as the network response is available. you will have to request your own free key from Google.name() == "coordinates") { coordinates = xml.readNext().get(QNetworkRequest(url)). Space characters are then transformed into + signs and the final location string is embedded into the full query URL. we print the error message to the status bar of the main window. url.arg(networkReply ->errorString())). while (!xml. networkManager. Otherwise. } This method first retrieves the text from the locationEdit widget. } The private parseXml() method (see below) is only executed if the network request completed successfully.addEncodedQueryItem("oe".addEncodedQueryItem("output". This is achieved through the QUrl class. which provides a convenient interface for working with URLs.addEncodedQueryItem("key". networkReply->deleteLater(). the request is submitted. The addEncodedQueryItem() method is used to add the parameters to the network request. The maps key (abcdefg) is for demo purposes only. url. "false"). "utf8"). The automatically applied encoding replaces all non-ASCII and control characters with a percentageencoded format. Qt will call our handleNetworkData() slot as a result of the connection that we set up in the constructor: 1 2 3 4 5 6 7 8 void XmlDataView::handleNetworkData(QNetworkReply *networkReply) { if (!networkReply->error()) parseXml(networkReply->readAll()). "xml").readElementText(). url. Finally. else statusBar()->showMessage(tr("Network error: %1"). After the response has been processed.clear().
Qt provides many more interesting features and modules like data models. readElementText() continues reading the stream up to the corresponding XML tag end element and returns all text in between. This might also be the case if there was an error while parsing the XML document (e. the while loop checks whether the parser has reached the end of the currently available data. } } 19 20 21 22 23 24 25 26 27 28 29 30 The QXmlStreamReader class in parseXml() behaves like an iterator.toDouble(). Long: " + QString::number( longitude)). These are well worth taking a look at – but.atEnd() call. In case the string actually contains the expected three values. SQL. } } } } if (coordinates.Qt in General 63 14 15 16 17 18 statusBar()->showMessage(tr("Successfully received XML data")). } if (xml. resultEdit->setText("Lat: " + QString::number( latitude) + ".at(0).error() << ": " << xml.error()) { qWarning() << "XML ERROR:" << xml. we set them as the new text for the resultEdit widget. if it is not well formed. We are only interested in the local name of the XML tag start elements. The three values are separated by commas. readNext() jumps to the next token. This completes the implementation of the Geocoding example. you should dive deeper into the mobile world and learn more about using Qt on your Symbian handset.lineNumber() << ")". In case the XML reader has not yet reached the end of the available data. If the Geocoding API was happy with the request.toDouble(). the QString coordinates member variable now contains the longitude. which incorporates many of the concepts introduced in this chapter. double longitude = l. meaning that it does not comply with XML syntax rules). Through the xml. double latitude = l. latitude and altitude of the placemark. we are waiting for the coordinates tag. You should now have a solid basic knowledge of Qt and be prepared for your first steps in writing your own Qt applications.isEmpty()) { statusBar()->showMessage(tr("No valid coordinates found in network reply")). Once this tag is found. . Of course. which is appended to our coordinates string variable.at(1). errorString() << " (line " << xml. This character is used to split the string into a QStringList. for now. threading and more advanced graphics. a list of strings (inherited from QList<QString>). More specifically.g.
64 Qt for Symbian Bibliography Blanchette J and Summerfield M 2006 C++ GUI Programming with Qt 4. San Francisco.digitalfanatics. NJ. Jakl A 2009 Symbian course materials: http://www. Prentice Hall PTR. Prentice Hall PTR.com/. Ezust A and Ezust P 2006 An Introduction to Design Patterns in C++ with Qt 4 (Bruce Perens Open Source). NJ. Upper Saddle River. No Starch Press. . Qt Development Frameworks 2009 Qt reference documentation: http://qt. Upper Saddle River.symbianresources.com/doc/. Molkentin D 2007 The Book of Qt 4: The Art of Building Qt Applications.html.nokia.org/projects/qt_tutorial/chapter02. Thelin J 2004 The independent Qt tutorial: http://www.
1 Introduction In the previous chapters. Moreover. location information and mobile messaging systems are some features that are typically applicable to portable systems only.org/qt-mobility) delivers a set of new APIs to Qt.gitorious. Consequently. For example. to name but a few. Furthermore. as in any other mobility library. a new set of APIs for utilizing mobile features in a cross-platform fashion is becoming a practical necessity. file-related functionality and multi-threading. By their nature. The APIs of the Qt Mobility project are real cross-platform APIs. Fitzek This chapter introduces the very first Qt Mobility APIs. Tony Torp and Frank H. it is only natural that they are provided for cross-platform development as an integral part of the general Qt. The Qt Mobility project v1. including facilities such as example networking. These escape the common cross-platform Qt libraries. netbooks and desktop computers. However. assuming of course that the associated facilities are available in the device in the first place. the Qt framework introduces a powerful way to create cross-platform user interface applications. As demonstrated.0 (http://qt. The goal of these APIs is to enable the use of mobile phone functionalities in Qt applications. These APIs provide access to features that are well known from other mobile programming systems. The Qt Mobility package implements a set of APIs that grants access to the most commonly needed mobility features without forcing the developer to implement platform-dependent native code like Symbian C++. Therefore. portable devices like smart phones have many special features. the framework not only improves many aspects of a mobile development experience by simplifying the use of associated . The APIs are easy to use and are designed for cross-platform usage. such as Python or Mobile Java. these system features exist on all platforms – including both the portable and desktop environments.4 Qt Mobility APIs Tommi Mikkonen. 4. these APIs allow the developer to use mobility-related features with ease from a single framework and apply them to phones. the general cross-platform portion of Qt also provides APIs for implementing the most important system features. Since Qt is now supported by a number of mobile platforms.P. we introduced the main concepts of general cross-platform Qt.
In the following we will briefly explain the different parts of the Qt Mobility API (Figure 4. 4.2 Bearer Management The fundamental goal of bearer management is to reduce developers' concerns when locating the best available connection from a list of possible IP bearers and 3G connections. source code can be reused over the Symbian border (which is covered in this book). or the connection can be selected transparently so that WLAN roaming can occur seamlessly. With the bearer management API.1 Qt Mobility APIs. The bearer management API controls the connectivity state of the system.1). The application developer is in control and if needed the application can . When a user starts to use a browser. • Always-on applications – such as email or IM – roam automatically between cellular packet data and WLANs. the appropriate access point is selected from available ones and a connection is made transparently. technologies. but also has applicability beyond the mobile device arena. Consequently. the user can start or stop communication interfaces and roam between access points in a transparent fashion. The user can select the best connection. Some examples of the bearer management functionality are listed below: • On-demand use of an appropriate access point.66 Qt for Symbian Figure 4.
case QNetworkConfiguration::UserChoice: // The access point is resolved by asking the user break. for example. case QNetworkConfiguration::ServiceNetwork: // System determines the best IAP available and starts it immediately break.3 Contacts The fundamental use case for a mobile phone is establishing communications. } QNetworkSession* session = new QNetworkSession( configuration ).isValid() || !canStartAccessPoint ) return. 4. . this is one of the most essential mobility extensions for Qt from the developer's viewpoint.1 Creating a Network Session QNetworkConfigurationManager is a class that manages the network configurations provided by the system. • The application developer can create a settings user interface. Therefore. Consequently. Most commonly this takes place with an already existing contact. if ( configuration. QNetworkConfiguration configuration = manager. const bool canStartAccessPoint = (configurationManager. where the user can select a certain connection to be used with the application. one of the special use cases of a mobile device is the management of contacts.defaultConfiguration().type() ) { case QNetworkConfiguration::InternetAccessPoint: // System starts the IAP immediately break. shows counters and allows the user to connect or disconnect. The following code example illustrates how a network session can be established without any user interaction: 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 QNetworkConfigurationManager configurationManager. • A connection manager application can be implemented with Qt. This application enumerates available connections. switch( configuration.Qt Mobility APIs 67 gracefully close TCP connections over the old bearer after setting up new TCP connections over the new bearer.2. 4. session->open().capabilities() & QNetworkConfigurationManager::BearerManagement). Class QNetworkConfiguration provides an abstraction of access point configurations.
setNumber("555112233"). name.2 Finding a Single Contact Detail The next code example illustrates how to get the phone number of a specified contact.setPostCode("33220").setRegion("Springfield). The example takes the first contact in the contact database and gets the phone number for it: .4 The Contacts API This API defines the structure and retrieval of contact data from local or remote backends. address. name.saveDetail(&number).setCustomLabel("Homie").68 Qt for Symbian 4. list. edit.setSubTypes(QContactPhoneNumber::SubTypeMobile).saveDetail(&address). The IDs of contacts are first fetched as a QList of contact IDs. name.setFirst("Homer"). // Create address detail QContactAddress address. The API offers operations such as create. address.setLast("Simpson"). homer. QContact homer. address. delete and lookup contact information.4. number. homer.setCountry("USA"). This is carried out in the following code snippet: 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 QContactManager* contactManager = new QContactManager( this ). adding contact details and saving it to the contact database via the QContactManager class. number. // Create name detail QContactName name.setContexts(QContactDetail::ContextHome).1 Creating a New Contact A contact can be created by creating an instance of the QContact object. // Save the contact to the contacts database contactManager->saveContact(&homer). homer.saveDetail(&name). homer. } 4. 4. // Create phone number detail QContactPhoneNumber number. number). number.setPreferredDetail("DialAction". regardless of whether the data is stored locally or remotely.4.
detail(QContactPhoneNumber:: DefinitionName). firstContact. Since location is an increasingly important piece of context for many applications. email. numerous mobile devices offer access to location information. The location API encapsulates basic geographical information about the user obtained from satellite or other sources. changing or adding the required details and then storing the updated contact in the contacts database. Information provided includes the following: • The date and time at which the position was reported.saveDetail(&email). QList<QContactLocalId> contactIds = contactManager->contacts(). QString phoneNumber = firstContact. 4.setNumber("555123321").4.details(QContactPhoneNumber ::DefinitionName). including latitude and longitude.org"). email.setValue("Label".setEmailAddress("homer.Qt Mobility APIs 69 1 2 3 4 QContactManager* contactManager = new QContactManager( this ). QContact firstContact = contactManager->contact( contactIds. QContact firstContact = contactManager->contact( contactIds. the location API is also an important mobile extension.value(0). In the case of Qt. // Change the phone number QList<QContactDetail> numbers = firstContact. • The velocity of the device that reported the position. phoneNumber. // Save the details firstContact. speed and altitude.5 Location One of the promises of mobile computing is context sensitivity.setContexts(QContactDetail::ContextWork). bearing. QContactPhoneNumber phoneNumber = numbers.simpson@email. . "Homer's work email").3 Editing a Contact Detail Contacts can be edited by first fetching the contact. 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 4.first() ).first() ). It enables a range of geographical applications such as maps. email. // Add an email address QContactEmailAddress email. // Save the updated contact to the database contactManager->saveContact(&firstContact).saveDetail(&phone). This can be achieved with the following piece of code: 1 2 3 4 5 6 QContactManager* contactManager = new QContactManager( this ).value(QContactPhoneNumber::FieldNumber). QList<QContactLocalId> contactIds = contactManager->contacts().
longitude. relative to true north.5.70 Qt for Symbian • The altitude of the reported position (height above sea level). The positioning info is then eventually passed through the positioningUpdated() signal with a parameter containing latitude. then request updates. The QGeoPositionInfoSource class is used to get the default positioning source of the device. If the source exists. altitude. This is realized with the following code: 1 2 3 4 5 6 7 8 9 10 11 12 // Get the default positioning source. SIGNAL(positionUpdated(QGeoPositionInfo)). • QGeoCoordinate – Defines a geographical position on the surface of the Earth.longitude(). } // Custom slot for getting the updates void handlePositionUpdated(const QGeoPositionInfo &info) { double latitude = info. The main classes of the location API are as follows: • QGeoAreaMonitor – Enables the detection of proximity changes for a specified set of coordinates.1 Getting and Following the User's Location The code example below gets registers for getting notifications on changes in user location. if (source) { connect(source.. The user class must create the source and request updates by calling the startUpdates() method. . • QGeoPositionInfoSource – Abstract base class for the distribution of positional updates. it can use either satellite data or some other positioning method. • QGeoPositionInfo – Contains information gathered on a global position.latitude(). • QGeoSatelliteInfo – Contains basic information about a satellite. source->startUpdates(). etc. If exists. Location data sources are created by creating a sub-class of QGeoPositionInfoSource and providing QGeoPositionInfo objects through the QGeoPositionInfoSource:: positionUpdated() signal. • The bearing of the device in degrees. 4. as location information. Clients that require location data can connect to the positionUpdated() signal and call startUpdates() or requestUpdate() to trigger the distribution of location data.coordinate(). SLOT (handlePositionUpdated(QGeoPositionInfo))). direction and velocity at a particular point in time.coordinate(). this. QGeoPositionInfoSource *source = QGeoPositionInfoSource:: createDefaultSource(). double longitude = info. • QGeoSatelliteInfoSource – Abstract base class for the distribution of satellite information updates.
// Set message body message. message.jpg"). // Add attachments QStringList attachments. It enables messaging services to search and sort messages.setBody("Here you go!"). which can also be used for retrieving messages and message data and other appropriate messaging-related actions: 1 2 3 4 5 6 7 8 QMessageServiceAction* serviceAction = new QMessageServiceAction( this ).6 Messaging A common interface for handling SMS.jpg"). The required message fields. body. attachments.setTo(QMessageAddress("myfriend. or to compose a message. 9 10 11 12 13 14 15 16 17 18 19 20 21 . // Create a new email message QMessage message. such as an email. The following code snippet creates a new email message and sends it to a specified email address. MMS and email messages is given by the messaging API. QMessageAddress::Email)). notify changes to messages stored.1 Creating and Sending an Email Message Creating messages is quite straightforward.bestis@emailaddress".append("Picture2. retrieve message data and launch the preferred messaging client either to display an existing message. MMS or SMS message.altitude(). message. 4. // Send the message serviceAction->send(message). 4. attachments and other data that can be added depend on the message type.Qt Mobility APIs 71 13 14 double altitude = info. which can be of various types. attachments. The API provides access to numerous operations associated with messaging.appendAttachments(paths). QMessage represents a message object. This is done by the class QMessageServiceAction. // Add required fields message. message. }.coordinate().setSubject("Pictures from our holidays :)").6. send messages with or without attachments.append("Picture1.setType(QMessage::Email).
7 Multimedia Multimedia has become a standard feature in mobile phones. In addition to playing and recording.2 Creating a Playlist of Videos and Playing Them in a Video Widget The class QMediaPlaylist can be used to create playlists for media types. this. . The method duration() returns the total playback time of the object media file: 1 2 3 4 5 QMediaPlayer* mediaPlayer = new QMediaPlayer. playlist->append(QUrl("/MyVideos/video3.mp4")). SLOT( myPositionChangedHandler(qint64))). QVideoWidget is a special widget for video playback. slide shows can be invoked using this API. mediaPlayer->setMedia(QUrl::fromLocalFile("http://music.72 Qt for Symbian 4. where communication is decoupled from both producers (publishers) and consumers (subscribers) of data. mediaPlayer->play(). The Qt Mobility API provides access to a multimedia library. This example creates a video playlist and uses the media player to play back the videos on a video widget: 1 2 3 4 5 6 7 8 9 QMediaPlayer* mediaPlayer = new QMediaPlayer( this ).com/song. player->play().8 Publish and Subscribe Publish and subscribe is a widely used messaging paradigm. 4. The signal positionChanged() is emitted with a parameter specifying the audio playback position in milliseconds from the beginning of the audio file. which offers an easy way to play and record audio and video in various formats. playlist->append(QUrl("/MyVideos/video2. The API sends signals of the progress of the media file playback.7. 4. other features can also be accessed using the API. The communication takes place asynchronously. SIGNAL(positionChanged(qint64)).1 Playing an Audio File The following code snippet plays an MP3 song in a remote website.mp4")). playlist->append(QUrl("/MyVideos/video1. For instance. mediaPlayer->setVolume(50).mp4")). Moreover. parentWindow ). FM radio can be used through this API. QMediaPlaylist* playlist = new QMediaPlaylist(player). 4. connect(mediaPlayer. most commonly using an additional data object.mp3" )).7. QVideoWidget* widget = new QVideoWidget( mediaPlayer. widget->show().
CDMA. 4. It is intended to be an enabling technology. Ethernet and others. Network keeps information about the network connection (e. Features lists the supported hardware on the device. WiFi. the application does not need to be concerned with the underlying protocol. with data being able to 'shadow' other data with the 'same key'. the values of the objects change but the relationships remain the same. and so forth. 4. Therefore. a string specifying the leaf or node. Moreover. As the context changes. a defined set of relationships. Qt and the service framework. connectivity. MAC address) and type of network such as GSM. For a software developer. They are addressed in the following: Version contains information for a range of supporting software on the device. The system information API offers access to discover system-related information and capabilities. Features include subsystems such as the camera. Display information provides access to display information (brightness/colour depth) from the system. because the service framework essentially is an abstraction layer.Qt Mobility APIs 73 The publish and subscribe API will enable context-sensitive access to information in future releases. such information may include details of different pieces of included software. the basis of a range of future applications. Device information provides access to device information from the system. WCDMA. information is available from the operating system and firmware to the version of WebKit. service is an independent component that allows a client to perform a well-defined operation. one of the most interesting mobile Qt extensions is a platform-independent method to discover services. there is a lot of information regarding itself.10 System Information Inside every mobile device. hardware characteristics. In terms of the framework. . where the servers are. this information is important. the service framework API defines a unified way of finding. For example. implementing and accessing services across multiple platforms.g. GPS. For example. the hardware peculiarities with networking and other low-level details. removable. and so forth. or require information on the system in order to customize themselves. The services are implemented as plug-ins installed on the device and can look for supporting external services running on a central server. The context is an example of a context ontology. Within the scope of Qt Mobility APIs. FM radio. The passed data is organized as a tree. CD-ROM or even if there no devices. since applications may need certain hardware features in order to be useful.9 Service Framework It is common for mobile devices to provide device-specific services. Bluetooth. Storage information details the presence of various storage devices such as internal.
The example snippet here fetches battery status information and then connects to get updates on battery status. keypad. or multi-touch. void MyClass::handleBatteryStatusChanged( QSystemDeviceInfo:: BatteryStatus batteryStatus ) { if( batteryStatus == QSystemDeviceInfo::BatteryCritical ) { // Do something } } 5 6 7 8 9 10 11 12 4. current profile and power state of the device: 1 2 3 4 QSystemDeviceInfo* deviceInfo = new QSystemDeviceInfo( this ). qwerty.1 Accessing Device Information The following code snippet illustrates how to get information synchronously from QSystem DeviceInfo about the underlying system and then request notifications when the state changes. vibrating. Power state details how the phone is currently powered up and whether it is charged or not. The example code demonstrates how to check which features are supported by the device: 1 2 3 4 QSystemInfo* systemInfo = new QSystemInfo(this). SIM indicates the presence of a SIM card.74 Qt for Symbian Battery status gives the energy status of the battery at certain levels. Input method determines the type of input method such as keys/buttons.10. // Getting the current language and country code of the device QString language = systemInfo->currentLanguage(). 4.SIGNAL(batteryStatusChanged(QSystemDeviceInfo:: BatteryStatus)). . Other similar signals can be connected for the Bluetooth state. dual SIM card or locked SIM card that can be retrieved. Profile enables the developer to check on the profile settings of this API for silent. connect(deviceInfo.SLOT(handleBatteryStatusChanged(QSystemDeviceInfo:: BatteryStatus))). this. Screensaver provides access to the screen saver and blanking. single touchscreen. QString countryCode = systemInfo->currentCountryCode(). normal and others. QSystemDeviceInfo::BatteryStatus batteryStatus = deviceInfo-> batteryStatus().10.2 Accessing System Information The next code snippet demonstrates the simple usage of QSystemInfo.
However.Qt Mobility APIs 75 5 6 7 8 9 // Check if the device has a camera if( systemInfo->hasFeatureSupported( QSystemInfo::CameraFeature ) { // Take a picture..2 Qt Mobility APIs. } 4. S60 3rdE FP1 S60 3rdE FP2 S60 5thE Service framework Messaging Bearer management Publish and subscribe Contacts Location Multimedia System information Yes Yes Yes Yes Yes Yes No Yes Maemo Maemo Windows Linux MAC 5 6 Mobile Yes No No No No No No No Yes Yes Yes Yes Yes No No No Yes Yes Yes Yes Yes Yes No Yes Yes Yes Yes Yes No No Yes Yes Yes No Yes Yes No No No Yes In this chapter. but over time the holes will be closed and more APIs will be added.11 Summary The motivation of the Qt Mobility APIs is that they can be used on any system as illustrated in Figure 4. Table 4.1..1 Platform compatibility. Symbian devices have many other features beyond the cross-platform Qt and Qt .2. we introduced the Qt Mobility API and the features that can be accessed through it. Figure 4. Other systems such as Windows Mobile or Maemo might not fully support the individual APIs as given in Table 4.
76 Qt for Symbian Mobility package. We will cover Symbian-specific mobile extension APIs in the next chapter. Forum Nokia Wiki provides a wide set of Qt-like wrappers that hide native Symbian C++ under APIs that provide Qt-like interfaces for utilizing Symbian-specific features. Bibliography Fitzek HF and Katz M (eds) 2006 Cooperation in Wireless Networks: Principles and Applications – Real Egoistic Behavior is to Cooperate! Springer. If you want to utilize those features. . Acceleration sensors and a camera are examples of features that exist in almost all the latest Symbian devices. you would normally need to implement your application against native interfaces.
P. We extend our application with native Symbian C++ using those native Symbian APIs that the platform offers. We can use a Qt-like approach for implementing the functionalities of sensors. In contrast to Qt Mobility APIs.1 Utilizing Platform Features beyond Qt APIs In the previous chapter we introduced Qt Mobility APIs for cross-platform development across various device types. a camera. but on the other hand new functionalities or flexibility are introduced. Symbian devices still have many platformspecific features that Qt libraries or Qt Mobility APIs do not reach. As richly featured smart phones. in our applications and we do not need to go too far beyond Qt-like programming. 5. . They are Qt-like API extensions provided for Qt on Symbian developers for easy utilization of the most important platform features beyond Qt APIs.5 Qt-Like Mobile Extensions Tony Torp and Frank H. which is known to have a very steep learning curve. The extensions introduced in this chapter and given in Table 5. Some of them overlap with Qt Mobility APIs and these are excluded from the list. The drawback with this approach is that then we have to do programming on native Symbian C++.. When implementing mobile applications. etc.5) but they are extensions offering Qt-like interfaces for application developers to utilize easily the key features of Symbian devices. The other approach is to make use of prefabricated wrappers offered by Forum Nokia Wiki. The goal of the APIs is to provide a high enough abstraction level for easy and simple usage for developers. Mobile extensions give developers Qt-like access to Symbian smart phone platform-specific features without the need to learn how to program in native Symbian C++. we are typically willing to take advantage of those features. We call them Qt-like APIs because they are not cross-platform Qt APIs (see Figure 1. A camera and sensors are examples of those features that exist in every latest Symbian device but are not yet covered by standard Qt APIs. We basically have two alternative approaches to utilize them from our Qt applications. The first alternative is the native choice. these APIs are not that easy to integrate without knowledge of Symbian. Fitzek This chapter gives an overview of native Symbian APIs. In the following sections we will introduce the current set of API extensions available for Symbian smart phone development.1 do not cover the whole set of extensions offered.
5.2 How to Use the Mobile Extensions in Your Project The extensions are API wrappers typically consisting of an object that implements the Symbian C++ API calls and a wrapper class providing Qt-like APIs for your application to use. which can be used to set. The API allows you to set an alarm that goes on or off at a particular time of the day. In the next chapter we give an overview of Symbian C++ with an example on how these wrappers are really implemented. receive call status notifications Launching viewer applications for file types. WriteDeviceData and WriteUserData. The main API is class XQAlarms. Using an extension might require certain capabilities to be added to your application project.78 Qt for Symbian Table 5. ReadUserData. expire time and message attached to the alarm. . Qt Mobility APIs and the current mobile extensions cover the most important features of Symbian smart phones. 5. If you need to use platform features beyond these and possibly want to implement your own Qt-like Symbian extensions. viewing current alarms and removing alarms on the device. using the Alarms API typically requires capabilities ReadDeviceData. modify and remove alarms.1 List of extensions described in this chapter. then you need to utilize native Symbian APIs and learn Symbian C++ concepts. Chapter 6 introduces the main concepts needed for native Symbian development with an example on how to implement Qt-like wrapper APIs. WriteDeviceData and WriteUserData depending on the method used.3 Alarms The Alarms API can be used for setting alarms. Class XQAlarm is used to store alarm data such as category. A list of alarms set on the device can also be retrieved with the API. The capabilities are listed in the extension documentation together with the API descriptions. ReadUserData. In order to use an extension you need to add the source files of that extension to your project in your IDE and build them together as part of your application source codes. API name Alarms API Calendar API Camera API Installer API Landmarks API Profile API Sensor API Telephony API Utils API Vibra API Description Set an alarm to go on at a particular time Access appointments in the device's calendar database Take pictures with the device's on-board camera Install a Symbian application from an install package List the available landmarks and add new landmarks Read profile information and set the active profile Detect the acceleration and orientation of the device Make circuit-switched phone calls. backlight control Use the vibra on the device to give physical feedback to the user Qt libraries. Using the API requires capabilities ReadDeviceData. For example.
QList<int> ids = alarms->alarmIds().2 Creating a Workday Wakeup Alarm Alarms can be created by creating an XQAlarm object and then adding the alarm with the XQAlarms instance.date(). alarmDateTime.setExpiryTime(alarmDateTime).3. // Create XQAlarm data object XQAlarm weeklyReport. QString alarmMessage = alarmToChange. 0)). weeklyReport.3 Changing the Time of a Specific Alarm Existing alarms can be modified.value(0)). QList<int> ids = alarms->alarmIds(). int alarmDay.Qt-Like Mobile Extensions 79 5.3.setMessage("Do weekly report"). weeklyReport. 1 2 3 // Create an XQAlarms instance and fetch ids XQAlarms* alarms = new XQAlarms(this).dayOfWeek(). if (alarmToChange. QDateTime dateTime = alarmToChange. alarms->addAlarm(weeklyReport). weeklyReport. 5. 14 15 16 .3. QDateTime alarmDateTime = alarmDateTime.expiryTime(). 5.1 Getting a List of All Alarms The following snippet creates a list of alarm IDs of all alarms that have been set.currentDateTime(). // Create XQAlarm data object to get the data of the existing alarm. The following code example creates a weekly repeated alarm for a weekly report from the current day onwards: 1 2 3 4 5 6 7 8 9 10 // Creating a workday wakeup alarm XQAlarms* alarms = new XQAlarms(this).setTime(QTime(15. XQAlarm alarmToChange = alarms->alarm(ids.message().repeatDefinition() == XQAlarm::RepeatOnce || alarmToChange. This code example shows how to change the time of a first alarm on the alarms ID list: 1 2 3 4 5 6 7 8 9 10 11 12 13 XQAlarms* alarms = new XQAlarms( this ).repeatDefinition() == XQAlarm::RepeatWeekly ) { alarmDay = dateTime.setRepeatDefinition(XQAlarm::RepeatWeekly).
3.addDays(1). changing and adding items. The other classes are as follows: • XQCalendar – the calendar database . // Delete the old alarm alarms->deleteAlarm(ids[0]). alarms->deleteAlarm(ids[0]). The Calendar API can be used for application access to the calendar database for retrieving.time() < QDateTime::currentDateTime(). } // Create a new alarm based on the alarm data XQAlarm updatedAlarm. alarms->addAlarm(updatedAlarm). updatedAlarm. // Set new alarm time to 15. 5.4 Deleting an Alarm Alarms can be deleted by the alarm ID. QDateTime alarmDateTime = alarmDateTime. 'ToDo' notes.repeatDefinition(). // If the time has passed. 5.setMessage(alarmMessage).setExpiryTime(alarmDateTime). The main class of the API is XQCalendar.00 QTime newTime = QTime(15. updatedAlarm.4 Calendar The Calendar API provides access to items in the calendar database of the device.setTime(newTime). 00). which represents the calendar database.80 Qt for Symbian 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 } int oldAlarmDefinition = alarmToChange. we add one day to the alarm time if (alarmDateTime.time()) { alarmDateTime = alarmDateTime. Appointments. anniversaries and other time-specific events are stored in the calendar database.setRepeatDefinition( static_cast<XQAlarm::RepeatDefinition>(oldAlarmDefinition)).currentDateTime(). The following code snippet deletes the first alarm from the alarm ID list: 1 2 3 4 XQAlarms* alarms = new XQAlarms( this ). // Get the list of all alarm ids and delete the first one (index 0) QList<int> ids = alarms->alrmIds(). updatedAlarm. alarmDateTime.
count().). entry. 12.2 Deleting Calendar Entries Deleting a calendar entry requires an entry ID for the entry. 7 )..)). entry. // Get the list of all entry IDs in calendar database // and delete entries after the specified date QList<ulong> entryIds = calendar->entryIds(). The following code snippet deletes all calendar entries after a specified date: 1 2 3 4 5 6 7 8 9 // Create a calendar object XQCalendar* calendar = new XQCalendar( this ).setTimeOffset( 60 ).setStartAndEndTime( QDateTime(.setSummary( QString("Find and buy a new tie") ).4. // Add the entry to the calendar database calendar->addEntry(entry).. QDateTime(. The XQCalendarEntry instance is created with specified data and then added to the calendar database by using XQCalendar. for (int i = 0. Using the API requires capabilities ReadDeviceData. entry. WriteDeviceData and WriteUserData. of appointment attendee • XQCalendarAlarm – alarm for a calendar entry • XQCalendarRepeatRule – for repeating calendar entries • XQCalendarWidget – widget for showing a month at a time. i < entryIds. The entry IDs can be fetched as a list by method entryIds() which returns the complete list of entry IDs.Qt-Like Mobile Extensions 81 • XQCalendarEntry – an entry in the database • XQCalendarCategory – an entry category • XQCalendarAttendee – name.. role. // Setting an alarm 60 mins prior to the entry XQCalendarAlarm alarm. ReadUserData. 5. QDate dayOfDoom( 2009. The following code snippet creates a 'ToDo' note with an alarm attached: 1 2 3 4 5 6 7 8 9 10 11 12 // Create a calendar object XQCalendar* calendar = new XQCalendar( this ). // Create a new ToDo entry XQCalendarEntry entry(XQCalendarEntry::TypeTodo).1 Creating a New Calendar Item Adding new items to a calendar is fairly straightforward.4.setAlarm( alarm ).. Single calendar entries can then be fetched and data can be checked.. alarm. i++) { . 5. etc.
Similarly. The main API class is XQCamera.82 Qt for Symbian 10 11 12 13 14 15 XQCalendarEntry entry = calendar->fetchById(entryIds[i]). The desired picture size can also be reset from the default of 640 × 480 pixels. The following code snippets demonstrate the usage. private: XQCamera* camera. then focus the camera and then actually take the photo. the camera focusing is ready or image capture is completed. XQViewFinderWidget* viewFinder.5 Camera Most Symbian smart phones come with a built-in camera. is a widget that can be used for previewing an image. 5. starting a viewfinder widget might end up in an error. then the user clicks the capture button to take the photo. Using the API requires capabilities MultimediaDD and UserEnvironment. if (entry. If the operation fails. which can then fetched by XQViewFinderWidget::error(). }. then the image is available and can be saved. .startTime(). Signals are emitted when the camera is ready. Capturing images typically consumes a lot of memory.date() > dayOfDoom ) { calendar->deleteEntry( entryIds[i] ). The other class of the API. focusing or capturing.5.1 Camera Initialization The next code snippet initializes the camera and connects the camera signals to slots in our application. which provides slots for focusing and capturing a picture. The default image capturing size is 640 × 480 pixels which can be changed by using the setCaptureSize() method: 1 2 3 4 5 6 7 8 9 10 11 12 class MyXQCameraUser : public QObject { Q_OBJECT protected slots: void imageCaptured(QByteArray imageData). The user class is MyXQCameraUser. With the API you can first see a preview of the image you might take. XQViewFinderWidget. The Camera API can be used for taking photos. } } 5. The API indicates an error on possible error situations during opening. so this should be considered when several images are open at any one time. the corresponding method returns false and the error code can be fetched by XQCamera::error(). then the viewfinder is started. Taking a picture with the Camera API involves a number of steps: first the camera class is initialized.
camera->releaseImageBuffer(). The button's clicked() signal is connected to the camera's capture() slot. 5.5. connect(captureButton. // Create a capture button and connect it to the camera's capture slot QPushButton* captureButton = new QPushButton("CaptureImage"). You can connect this to a slot in your application that will handle the captured image. // Connect to the captureCompleted signal connect(camera. Then the viewfinder is started again: 1 2 3 4 5 6 7 8 9 void MyXQCameraUser::imageCaptured(QByteArray imageData) { // Stop the viewfinder and show the captured image in the viewfinder viewFinder->stop().Qt-Like Mobile Extensions 83 13 14 15 16 17 18 // Create a camera object and set the capture size camera = new XQCamera(this). The camera class will emit a captureCompleted() signal when the image capture is completed. SLOT( imageCaptured(QByteArray))). . viewFinder->setImage(capturedImage). viewFinder. SIGNAL(cameraReady()).2 Using the Viewfinder Widget The viewfinder is started when the camera is ready. SIGNAL(clicked()).960)).3 Taking a Photo Clicking the 'CaptureImage' button initializes the image capture process. // Start the viewfinder when the camera signals it is ready connect(camera. 19 20 21 22 23 5.5. this. 192)). viewFinder->setCamera(*camera). // Get the image data into an image class QImage capturedImage = QImage::fromData(imageData). The following code stops the viewfinder and the captured image is shown for 5 seconds in the viewfinder widget. SIGNAL(captureCompleted(QByteArray)). SLOT(capture)). SLOT(start())). viewFinder->setViewfinderSize(QSize(256. camera. set the source camera and the size of the image viewFinder = new XQViewFinderWidget. We connect the cameraReady() signal straight to the start() slot of the viewfinder: 1 2 3 4 5 6 7 // Initialize the viewfinder. camera->setCaptureSize(QSize(1280.
sisx"). this. On the Symbian platform.6. So you can use this API silently to install applications or you can create for example your own installation user interface. so this is how you specify which application to uninstall.84 Qt for Symbian 10 11 12 13 // Restart the viewfinder after 10 seconds QTimer::singleShot(10000. UID3. SLOT(installationFailed())). Each Symbian application is identified by the system through a unique application identifier. SIGNAL(applicationInstalled()). SLOT( installationSucceeded())). this. After . The Installer API provides a method for fetching the list of UIDs or names of all applications currently in the system.sisx extension.6 Installer The Installer API can be used to install and uninstall applications without notifying the user through the standard installation dialogs. SLOT(start())). SIGNAL(error()). After installation is completed. // Connect the signals and slots connect(installer. viewFinder. connect(installer.6. either an applicationInstalled() or error() signal is emitted depending on whether the installation was successful or not: 1 2 3 4 XQInstaller* installer = new XQInstaller(this). the installation package is referred to as a SIS file and has a . Installing new applications is done by specifying the full path of the SIS file of the application. // Add possible error handling code here } 5 6 7 8 9 10 11 12 13 14 15 16 5.1 Installing an Application in the Background without Notifying the User The following code snippet shows how to install an application from an installation file. } 5.2 Uninstalling an Application in the Background without Notifying the User The snippet below shows how to uninstall an application without informing the user. Using the API requires capability TrustedUI from the application. Each application has a unique identifier. // Install an example package from the installs folder bool result = installer->install("c:\\Data\\exampleapplication. The Installer API can also be used to get a list of all the applications that are installed on the device. // Check that the installation started if (!result) { // Installation start failed XQInstaller::Error error = installer->error(). 5.
icon. // UID3 of the application uint appId = 0x12345678. security failure.6. // Connect to the applicationRemoved() signal connect(installer. this.Qt-Like Mobile Extensions 85 the process is completed. // Uninstall the application with the given ID bool result = installer->remove(appId). either an applicationRemoved() or error() signal is emitted depending on whether the uninstalling was successful or not: 1 2 3 4 XQInstaller* installer = new XQInstaller(this). SIGNAL(error()). The Landmarks API provides methods for adding landmarks and listing available landmarks. e. 5. connect(installer. // Get a list of applications by name QList<QString> applications = installer->applications(). which might be maintained locally on your device or. SIGNAL(applicationRemoved()).keys(). SLOT( uninstallationFailed() )). // Add possible error handling code here } 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 Possible error situations can arise from the system. The list can be fetched as application names or application UIDs: 1 2 3 4 5 6 7 XQInstaller* installer = new XQInstaller(this). // Check that the uninstall started if (!result) { // Uninstall failed XQInstaller::Error error = installer->error(). SLOT( uninstallationSucceeded())).values(). on a remote server that your device can access over the Internet.g.3 Getting a List of all Installed Applications in the Device The Installer API can be used to get a list of the applications that are currently installed on the device. // Get a list of applications by UID QList<uint> uids = installer->applications(). for example. package not supported or installer busy. Landmarks are organized in landmark databases. not enough memory. address details. 5.7 Landmarks A landmark is a location tag with a name and possible other data such as description. . this.
a description and other possible details. query a description from the user and add the newly created landmark to the database.addCategory("Amusement"). QString name = landmark.setName("Wonderland"). 20. The class XQLandmark describes a landmark.count(). QString description = landmark.setPosition(40. //. 5. landmark. The following code snippet creates a new landmark object with a name and coordinates and adds it to the landmarks database: 1 2 3 4 5 6 7 8 9 // Create a new landmark and set the name and location information XQLandmark landmark. The landmarks can be fetched in one list containing landmark IDs. position information. } .321).1 Creating a Landmark for the Current Location The Landmarks API enables you to store details about a particular location and the Location API can used to supply the coordinates of your current location.2 Getting a List of All Landmarks in the Landmark Database The next code snippet shows how to use the Landmarks API to get a list of all landmarks in the landmarks database.86 Qt for Symbian The main API class is XQLandmarkManager. 5.description(). A common use case will be to get current location. // Go through all the landmark items in the list for (int i = 0..7. qreal longitude landmark. A single XQLandmark can then be accessed by the ID: 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 XQLandmarksManager* landmarksManager = new XQLandmarksManager(this). landmark. which gives you access to the landmark database.name(). Adding a new landmark can typically be related to the current location information.longitude().value(i)).. qreal latitude = landmark. which can be obtained through the Qt Location Mobility API. Applications using the API require capabilities ReadUserData and WriteUserData. i < ids.123. landmarksManager->addLandmark(landmark).7. It provides methods for adding landmarks and getting the list of currently available landmarks. // Add the landmark to the landmark database XQLandmarksManager* landmarksManager = new XQLandmarksManager(this). // Get list of all landmark IDs from the database QList<int> ids = landmarksManager->landmarkIds(). ++i) { XQLandmark landmark = landmarksManager->landmark(ids. which can consist of a name.latitude(). landmark.
ProfileMeetingId. The API contains methods for modifying predefined profiles. ProfileDriveId } 5. the phone will not play any sounds when such an event occurs. Using the API requires capability WriteDeviceData. The main class of the API is XQProfile. ProfileOutdoorId.8. The profiles API only works for the predefined profiles so custom profiles are not supported.1 Getting the Current Active Profile The following code snippet shows how to use the Profile API to get the profile that is currently active on the device: 1 2 3 4 XQProfile* profile = new XQProfile(this). message alert tone or ringing volume can be set by simple API calls.2 Setting the Current Profile to Silent The following code snippet shows how to use the Profile API to set the current profile to flight mode.8 Profile A profile defines the sound scheme of when various events like incoming messages or phone calls are received. a small beep will play in the case of an incoming call or message. the network connectivity is then set off: 1 2 3 4 XQProfile* profile = new XQProfile(this).Qt-Like Mobile Extensions 87 5. When the meeting profile is active.8. The active profile is enumerated as: 1 2 3 4 5 6 7 8 9 enum Profile { ProfileGeneralId. When the silent profile is active. // Get the current profile XQProfile::Profile activeProfile = profile->activeProfile(). The API does not provide methods for creating new profiles or modifying profiles that are not predefined. 5. ringing tone. The General profile is the usual profile with user-selected ringing tones and message alert tones. . ProfilePagerId. ProfileSilentId. For example. ProfileOffLineId. The Profile API can be used for changing between different profiles and also for fetching the current active profile. The method isFlightMode() can be used to check if the phone is in an offline state and the network connectivity is disabled. // Set the profile to Silent bool result = profile->setActiveProfile(XQProfile::OffLineId).
5 5. // Set ringing profile to maximum. Y and Z dimensions. if the device is in free fall then the value of each axis is zero. // Start listening X-rotation updates with the resolution set connect(orientation. i.9 Sensors There are two types of sensors available through the Sensor API extension. // Opens orientation sensor data flow orientation->open(). 5. The orientation of the device affects the acceleration sensors due to the acceleration caused by the Earth's gravity.88 Qt for Symbian 5. Rotation is defined by the X.9. Orientation sensors can be used for getting the display orientation or. The display orientation describes the current orientation in a rough way. The new rotation angle is sent as a signal parameter: 1 2 3 4 5 6 7 8 9 10 11 12 XQDeviceOrientation* orientation = new XQDeviceOrientation(this). The latter applies to all coordinates X. The resolution is set here to 15 degrees orientation->setResolution(15).8. SLOT(rotationUpdated(int))). XQProfile:: ProfileGeneralId). namely orientation (Figure 5. . each varying between 0 and 359 degrees (Figure 5. the vibrating alert to the general profile is also set to 'no vibra': 1 2 3 4 XQProfile* profile = new XQProfile(this).1) and acceleration sensors. XQProfile::ProfileGeneralId). bool vibra = profile->setVibratingAlert(false. volume level 10 bool volume = profile->setRingingVolume(XQProfile::RingingVolumeLevel10. Y and Z.3 Setting the Ringing Volume of the General Profile to Maximum The following example modifies the general profile by setting the ringing volume to maximum. the rotation angle of the device. specifying the direction in which the device's display is heading. In fact. The API notifies the client by sending signals orientationChanged() and xRotationChanged(). more accurately.2). SIGNAL(xRotationChanged(int)).1 Receiving Notification of Changes in Rotation and Orientation The following code snippet uses the orientation sensor to receive notification of when the device is rotated in the X direction by at least 15 degrees and when the device orientation changes. such as moving the device up or down. The API for accessing the orientation sensor is XQDeviceOrientation. You can use the acceleration sensor extension to determine the acceleration of the device. this.e. Therefore you cannot assume that the axis values are zero when the device is still. // Set the number of degrees the device must rotate // before you are notified. This is useful for detecting movement gestures.
SLOT(orientationUpdated(XQDeviceOrientation::DisplayOrientation ))). this. The current rotation angle can also be fetched synchronously using the following simple query API: 1 2 3 4 // We read the current rotation (synchronous) int xRotation = orientation->xRotation(). SIGNAL(orientationChanged(XQDeviceOrientation:: DisplayOrientation)). .1 Orientation. int zRotation = orientation->zRotation(). 13 14 15 16 // Start listening changes in display orientation connect(orientation.Qt-Like Mobile Extensions 89 (a) (b) (c) Figure 5. int yRotation = orientation->yRotation().
2 The device's own coordinate system.). . SIGNAL(lineStatusChanged(XQTelephony::LineStatus.10. etc.10 Telephony The Telephony API extension brings voice telephony dialling and line monitoring functionality to our applications. telephony->call("+358301234567"). 5. You can do this by creating an XQTelephony instance and connecting the lineStatusChanged() signal to a slot method in your application. The following code shows the connection of the lineStatusChanged() signal to the application's handleStatusChange() slot: 1 2 3 XQTelephony* telephony = new XQTelephony(this). No packet-switched telephony is supported. The main API class XQTelephony provides methods for making circuit-switched telephone calls and monitoring the call line status (idle. 5. connect(telephony.2 Receiving Notification of When Phone Call Status Changes The call line status can be monitored by using a signal and slot mechanism.1 Making a Circuit-Switched Telephone Call This simple API opens a voice telephony call to a telephone number specified by parameter: 1 2 XQTelephony* telephony = new XQTelephony(this). You can also use the Telephony API to inform you when the call line status changes. when a phone call starts or ends. QString)). dialling. 5.90 Qt for Symbian Figure 5. hold.g.10. This API can only be used for traditional circuit-switched telephony calls. e. connected. ringing.
11 Utils The Utils API provides assorted platform-specific utilities. The API XQUtils can be used to launch a default viewer application for certain file types. XQConversions. // Our slot for handling telephone line status changes void MyTelephoneLineListener::handleLineStatusChange(XQTelephony:: LineStatus status. e. This API could be useful. Symbian devices have a background process running and detect user activity on the device. The next chapter covers the most important Symbian coding concepts. Take action } } } 8 9 10 11 12 13 14 15 16 5. QString number) { switch(status) { case XQTelephony::StatusRinging: { // Incoming call. timer->start().g. // Create a timer that goes off once every second and start it QTimer* timer = new QTimer(this). 5. So this code keeps the background lights of the device on. . key or pen presses or slider movements. which is very useful when mixing Symbian C++ and Qt code.Qt-Like Mobile Extensions 91 4 5 6 7 this. SLOT(handleStatusChange(XQTelephony::LineStatus.11. e. QString))).1 Keeping the Device Backlight Turned On The following code has a timer that goes off once every second and uses the method XQUtils::resetInactivityTimer() to reset the system inactivity timer. If there is no activity for a few seconds the timer expires and the backlight is switched off. The Utils API also offers a method for applications to reset the system inactivity timer to keep the backlights on. videos or pictures: 1 2 3 static QString videosPath() static QString imagesPath() static QString picturesPath() The Utils API also has another class. The timer is reset whenever there is some user activity. in game applications where the user has to see the board for a while when thinking about the next move: 1 2 3 4 5 6 7 XQUtils* utils = new XQUtils(this).g. The API also provides methods for fetching the file paths of certain stored items such as images. timer->setInterval(1000). It provides methods for converting Symbian descriptors and QString and vice versa.
5. Possible values are between -100$\%$ and 100$\%$. vibration off and vibration on. 5. SIGNAL(timeout()). The actual intensity depends on the hardware. 5. It is possible that the user has set the vibration off. utils. // Convert the descriptor back into another QString QString anotherBookName = XQConversions::s60DescToQString( * bookNameDescriptor ).1 Switching on the Vibration Function The code here uses the Vibra API to switch on the vibration function for 2 seconds at 80% intensity: 1 2 3 XQVibra* vibra = new XQVibra(this).3 Converting between QString and HBufC* The following simple code snippet allows conversion from QString to HBufC and back again: 1 2 3 4 5 6 // Allocate the QString QString bookNameString("Qt for Symbian").12. 4 . in silent mode. The main class of the API is XQVibra. The API has an access method currentStatus() which returns the status.11. 5. The intensity value can be between −100 and 100. Vibration can be started and stopped by invoking methods start() and stop(). vibra->setIntensity(80).12 Vibra The Vibra API can be used to vibrate the device. utils->launchFile("MyPicture. // Convert to a descriptor HBufC* bookNameDescriptor = XQConversions::qStringToS60Desc( bookNameString ).92 Qt for Symbian 8 9 // Connect the timer's timeout() signal to XQUtils::resetInactivityTime() connect(timer. The vibration intensity can be set by the method setIntensity(). which can also be used for getting the vibration settings from the current profile. Intensity value 0 stops the vibration. // Set the vibration intensity to 50$\%$. SLOT(resetInactivityTime())). The signal statusChanged() is also emitted when the vibration status changes between vibration not allowed.11. The status can be fetched by invoking the currentStatus() method.g.2 Launching a File with the Default Viewer Application The code snippet below launches a system default viewer application for JPEG files: 1 2 XQUtils* utils = new XQUtils(this). so that can easily be checked by the API.jpg"). e.
.Qt-Like Mobile Extensions 93 5 6 7 8 9 10 11 12 // Activate the vibra function for 3 seconds vibra->start(2000). //.. // Vibra can be stopped explicitly before the timer by calling vibra->stop()..
Developers can use the Qt framework to create new applications and port existing Qt applications to devices running Symbian OS with 5th Edition v1. Symbian OS has its own fundamental types defined as a set of typedefs in the Symbian header file e32def. . This requires higher level tools to speed up the development and increase software quality.0.1 Data Types and Symbian OS Class Naming Conventions Instead of using native C++ types. In this chapter we present an overview of the Symbian OS main features as well as Qt Native Symbian Extensions.2. This is necessary to keep compiler independence. including modules for networking. With the increasing power and dissemination of smart phones.6 Qt Apps and Native Symbian Extensions Angelo Perkusich. the demand for software is also growing. such as where objects may be created (on the heap. on the stack. concurrency and accessing native smart-phone features. as well as 3rd Edition FP1 and later devices.2. Symbian OS types should always be used instead of the native ones. As a consequence of this approach. Qt is the most promising solution for achieving massive and high-quality application development. Symbian OS offers a fully featured framework for developing applications in the C++ language. a native exception handling mechanism. must not contain any member data implementing destructors. hence. instead of TAny. Developers should use void when a function or method has no return type.3). In this context. mobile operating system that is embedded in a large diversity of smart phones today. By convention.2 and 6. 6. with different characteristics. When Symbian C++ was created.h. Kyller Costa Gorgônio and Hyggo Oliveira de Almeida Symbian OS is an open. as described in the following: T classes behave in the same way as the fundamental built-in data types. class conventions were defined and named with a prefix according to the type. T stands for Type. named leaving. was used instead of the standard C++ exception handling. T classes contain all their data internally and have no pointers. or on either) and how those objects should later be cleaned up. Closely related to leaving is the use of the cleanup stack and two-phase construction (see Sections 6. there are several class types on Symbian OS. These classes have an explicit destructor and.
M classes or 'mixin' are often used in call-backs or observer classes. and there is no need for this to be done explicitly in the constructor. and to avoid memory leaks you should use an idiom named two-phase construction. for which they are intended. Since Symbian v9. a C class typically needs to call code which may fail.96 Qt for Symbian references or handles to data. User and Math. At this point you can observe that the use of the naming convention for classes helps the creation.2. It is now possible for a T class to have a destructor to be called when the object goes out of scope. They are used for utility classes that cannot be instantiated.2. e.3.1. and the behaviour of a user-defined class can always be matched against the Symbian OS class characteristics. Thus. Note that in most cases only pure virtual functions are defined for an M class. 6. use and destruction of objects. The mains of this class. so a CBase-derived object is destroyed properly by deletion through a base class pointer. they derive from the CBase class (see e32base. As descriptors hold . if used in functions that may leave. Such a style ensures that even if you are not familiar with a class. such as User::After(200). are (i) safe destruction: CBase has a virtual destructor. use it and destroy it. see Section 6.1 Descriptors Descriptors encapsulate strings and binary data in Symbian OS and are used to manipulate and to provide access to data. Also. R objects must be made leave safe.h). as opposed to T classes.2). You can call their functions using the scope-resolution operator. unless that data is owned by another object responsible for its cleanup (see Section 6. resulting in the suspension of the currently running thread for 200 microseconds. Descriptors allow efficient and secure string and binary data manipulation for memory-limited devices. They are often small and usually contain no other member data besides the resource handle. and (iii) private copy constructor and assignment operators: CBase classes declare these to prevent calling code from accidentally performing invalid copy operations. which identifies the underlying memory layout of the data. C class objects must always be created on the heap and may contain their own pointers. When instantiated. A static class is sometimes implemented to act as a factory class. by using the cleanup stack. which are inherited by every C class. this is no longer the case. They are safe since buffers can be controlled and the programmer can keep control of memory usage. R classes own an external resource handle.g. R classes may exist as class members or as local stack-based variables.2).2..1. Each descriptor object holds the length of the string of data it represents as well as its 'type'. avoiding memory leaks. and thus all member data in a CBase-derived object will be zero filled when it is first created. you can be sure of how to instantiate an object. (ii) zero initialization: CBase overloads operator new to zero-initialize an object when it is first allocated on the heap. the M class is an abstract interface class which declares pure virtual functions and has no member data. Static classes have no prefix letter and contain only static member functions. Whenever you use them on the heap. you must guarantee that the memory allocated is released properly (see Section 6. for instance a handle to a server session.
The base classes provide common APIs for modifiable and non-modifiable descriptor operations. such as function Set(). There are separate descriptor classes for data stored in the descriptor. there is a further distinction between those which are stack based and those created on the heap. named 'buffer' descriptors. Descriptors can also exist in either 8-bit ASCII or 16-bit Unicode format. Descriptors are defined by fundamental classes TDesC and TDes implementing constant functions such as Length(). Further. which typically lives on the program stack. which lives on the program heap. Pointer descriptors contain a pointer to data. TBuf<n> and TBufC<n> are buffer descriptors. Also. An example of a heap descriptor is HBufC. TBufC and HBufC are directly derived from the TDesC class. they do not need to be null terminated and can thus be used to store binary data as well as text. As illustrated in Figure 6. Observe that the trailing C indicates that the descriptor is non-modifiable. There are three types of descriptors: Buffer descriptors store the data as part of the descriptor object. replacing or appending to the data.Qt Apps and Native Symbian Extensions 97 Figure 6. named 'pointer' descriptors. They are used for larger amounts of data and are resizable. there are a number of descriptor classes sharing the same base classes. The concrete classes add only initialization data during construction time. The TDes class is derived from TDesC and implements functionalities to . The descriptors TPtrC.1 Descriptor class hierarchy. These descriptor types are used for lookup and comparison. which lives elsewhere in memory. They are used for smaller amounts of data with a fixed maximum size.1. or in a separate area of memory. TPtr<n> and TPtrC<n> are pointer descriptors. and those which may be changed by formatting. Heap descriptors store the data as part of the descriptor object. there are descriptor types which may be accessed but not modified. Size() and Find(). which are invariant to the implementation type. length information.
Member data is used to store the maximum length for the descriptor.2 Memory Management As mentioned earlier. was introduced. and this is also the case for leaving methods. or throw an exception. On the other hand. The most basic class is TFixedArray. such as ConstructL. Format(). named a TRAP harness. to be used when you know at build time how many data items the array will contain. Whenever an error condition or abnormal event happens. Whenever you want to capture the exception. among others. for example. due to the lack of either main or mass memory space. the cleanup stack destroys each of the resources allocated dynamically.1 Leaves and Exception Handling In Symbian OS the use of conventions for names is very strong. lightweight exception handling mechanism. and the leave is propagated back through all calling functions until the first function containing a Trap() or Trapd() macro is found. Append(). you have to know how to mix leaves and exceptions in such a way that the ported code behaves as expected. An example of a leaving function is as follows: 1 2 3 4 5 void ProcessL() { //. Developers working on Symbian OS must use the cleanup stack to keep track of resources to which the only pointer is an automatic variable. A leave causes the execution of the active function to terminate. when Symbian OS was developed there was no mechanism for handling exceptions in C++. } The User::Leave() method is a static method that invokes the leave mechanism.2. it offers various classes than can be used to define static and dynamic arrays. A function name ending with LC means that this function may leave and it will also push one item on the cleanup stack. The developer must take into account that local resources.2 Arrays Symbian OS does not include an implementation for collections found in the Standard Template Library. will be 'orphaned'.. error handling based on leaves is still a fundamental part of Symbian OS. such as Copy().g. Thus. A leave propagates the error to a point in the calling code to be properly handled. When a leave occurs. 6. This section describes these classes. Thus. a catching function must be defined. leaves may occur. therefore resulting in either memory or handle leaks.. named 'leave'. which is a static array class.98 Qt for Symbian change data. Instead. 6.1. 6. Replace() and Trim(). such as memory allocated on the heap. for example: . e. Finally. Note that porting standard C++ code to Symbian OS is now easier because it supports C++ standard exceptions. a function name ending with LD means that this function may leave and the item that has been pushed on the stack can be released. if(error) User::Leave(). even though only standard C++ exceptions are used. since Symbian OS v9. a native. A function name ending with L means that this function may leave.
if(error) { } Note that when the function leaves.2. Sometimes. you clean the memory. the cleanup is also performed in the context of leaving. CleanupStack:: PopAndDestroy() As you can see. This is done through a Pop(object) statement.Qt Apps and Native Symbian Extensions 99 1 2 3 4 5 void CatchingL() { //. When you no longer need the object. which is discussed next. there is a stack. In such a case.. if an object is created with NewLC. You can also call PopAndDestroy to do both actions in a single step.2 The Cleanup Stack To ensure that objects allocated on the heap are properly deallocated. If the OperationThatCanLeaveL() leaves. required to recover any byte of data that can become orphaned by leaving. To avoid this situation you must ensure that when you leave. it will already be pushed on the cleanup stack at creation. for example. In the case when the execution leaves. thus leaving the demo object on the heap. delete demo. OperationThatCanLeaveL(). it is provided only in order to check that you pop the expected object. named 'cleanup stack'. It is not necessary to specify the object but it is useful to catch errors in debug build (the application panics if the popped object does not match with . The most important issue is the cleanup stack. where objects that need to be deallocated later are pushed on. objects are popped from the stack and destroyed automatically. When an object is created by new or NewL. OperationThatCanLeaveL(). you have to pop the object from the cleanup stack to avoid double deletion. thus leaving currently allocated objects on the heap and leading to a memory leak. ProcessL(). CleanupStack:: PushL(demo). 6. When the object is already on the cleanup stack. // } And you must set up a trap such as: 1 2 3 TRAPD(error. On the other hand.. So the leaving mechanism is strictly connected to the resource management and cleanup system. an object may change ownership: if you put it in an array. it immediately returns. you have to push it on the cleanup stack if any action that follows can leave. delete demo will never be reached. If the execution is performed normally. CatchingL()). the cleanup stack. it should be destroyed. the array will take ownership and the array cleanup routine will be in charge of deleting it. Consider the code snippet: 1 2 3 CDemo* demo = new CDemo. The object parameter is not required. you should remove it from the stack with Pop and then delete it. You must use the cleanup stack as follows: 1 2 3 4 CDemo* demo = new CDemo(). the object that must be deallocated is pushed on a deallocation stack.
the class can be implemented without the need to test each member variable to see if it is valid before using it.e. A class typically provides a public static function which wraps both phases of construction. Note that there is also a NewLC() function in the class CExample. This could be slightly less efficient since this would require an extra PushL() call to put a pointer back on the cleanup stack. all functionality is provided in a non-typed base class: . The first phase is the standard C++ constructor which is called by the new operator. Before it is called. To avoid memory leaks the code called by this constructor should not be able to leave. Consider the case when the constructor leaves: the memory already allocated for the object as well as any additional memory the constructor may have allocated will be orphaned. If a leave occurs. so it can be called without first having an existing instance of the class. According to the thin template pattern. an R type. For instance. Each factory function returns a fully constructed object. if an object exists. a code within a constructor should never leave.3 Two-Phase Construction Two-phase construction ensures that all objects being constructed and initialized do not leave before being stored in the cleanup. Note that objects of C classes should be initialized using an object constructed in two phases: 1. That is. In order to avoid this situation. it has been fully constructed. 2. Note that the cleanup stack can be used in other ways. the constructor is called to initialize it. if an object is initialized entirely by two-phase construction. but its implementation leaves a pointer on the cleanup stack when it returns. The factory function is typically called NewL() and it is static. the resource is closed.100 Qt for Symbian the parameter). In release builds. must be closed after use.2. Whenever an object is constructed on the heap. This method is also a factory function. either if there is insufficient memory to allocate the object (i.4 Thin Templates A thin template allows code reuse in Symbian OS to avoid code duplication. the object is placed on the cleanup stack so the memory allocated for the object is leave safe. The second phase of the construction is where the code that is called may leave. The secondphase constructor is typically named ConstructL. The NewL() factory function is implemented in terms of the NewLC() function rather than the other way around. providing a simple and easy way to identify means to instantiate it (the two construction methods can then be made private or protected to avoid accidental usage).2. It can be pushed on the stack with CleanupClosePushL and when you execute PopAndDestroy(). or leaves. defining an external resource. the result is an efficient implementation. 6. if operator new(ELeave) leaves) or if the second-phase ConstructL() function leaves for any reason. the check will be disabled. This means that. Since it is not necessary to test each member variable before using it. the cleanup stack calls the destructor to deallocate any resources which have already been successfully allocated and frees the memory allocated for the object itself. 6.
in containers. When used in a program. named EXEXP. it generates no extra code. program code exists only once. This code is exported from its Dynamic Link Library (DLL). The derived template class is thin: it generates no new code at all. DLLs are further divided into separate types. // works fine anotherarray. } } Because this class uses only inline functions. The base class may contain an arbitrary amount of code. normal templates would generate separate code for the integer array and Boolean array. avararray. An EXE runs separately and a DLL is dynamically linked into the program that loads it. Other supported types are: physical and logical device drives. EXE and PLUGIN. PDD and LDD. ECom is a client/server framework in Symbian OS that provides a service to instantiate. Symbian OS uses thin templates. a static library with binary code that is included in compilation time. such DLLs are automatically loaded by the system. However.3 Executable Files The most commonly used Symbian OS target types are DLL. the class is type safe to its users. The details of the idiom are hidden from the application programmer so they can be used like normal C++ STL (Standard Template Library) containers. like integer and Boolean. so it exists only once. resolve and destroy plug-ins.Insert( TInt( -1 ) ). and an executable which exports functions that can be used by other applications or DLLs.Insert( TInt( 20 ) ). respectively. Polymorphic DLLs implement an abstract API such as a device driver or a GUI application. } This base class has the real code. but still there is type safety for all array types. An example of Symbian OS container usage is described below: 1 2 3 4 5 CArrayPtrSeg<TInt> avararray( 16 ). named LIB. Shared library DLLs provide a fixed API that has several entry points potentially called by the user. Two of the most important DLL types are shared library DLLs and polymorphic DLLs. e. A derived template class is implemented as follows: 1 2 3 4 5 6 7 class CArrayFix<T> : public CArrayFixBase { inline const T& At(TInt aIndex) const { return(*((const T *)CArrayFixBase::At(anIndex))). since casting is encapsulated in the inline function.g. CArrayPtrSeg<TBool> anotherarray( 32 ). 6. UID is a 32-bit value that uniquely identifies a binary and can be as follows: . An ECOM plug-in allows you to encapsulate functionality in a DLL and access it from multiple clients through an interface class. The user uses the thin templates as normal template classes. With thin template patterns. // does not compile // go to Boolean array In this example.Qt Apps and Native Symbian Extensions 101 1 2 3 4 class CArrayFixBase { IMPORT_C const TAny* At(TInt aIndex) const.
1 is said to be a secure platform because of changes to the operating system to extend its security model and ensure more protection against malware or badly implemented software. ROM-based EXEs allocate RAM only for read/write program data. The secure platform prevents programs from acting in unacceptable ways. for example. irrespective of whether these actions are intentional or unintentional. read-only static data and read/write static data. In this case. Such a signing approach avoids applications assigning to themselves capabilities prior to installation. problems with locking up the phone. and must be included in the MMP file of any application. UID2 is used to differentiate between shared library and polymorphic interface DLLs. UID2 is KSharedLibraryUid(0x1000008d). Thus. 6. So. no loading is required. the Symbian OS installer verifies whether the application has the proper capabilities by means of a digital signature issued by a trusted authority. for shared libraries. ROM-based code is executed in place so no copying is required. For instance. or affecting other software or the network. Refer to the SDK help to get more detailed information about them. For polymorphic DLLs. When a DLL is loaded for the first time. they cannot have writable static data. the value varies depending on their plug-in type. EXE programs in Symbian OS are not shared. so that the DLL is unloaded when no threads are using it. . compromising user data. Values must be requested from Symbian. it is reallocated to a particular address. Symbian OS maintains reference counts. This avoids. A total of 20 capabilities are provided in Symbian OS.symbiansigned.102 Qt for Symbian UID1 is the system-level identifier that distinguishes between EXEs and DLLs and is built into the binary by the build tools depending on the target type. software and system or user data. Dynamically loaded link libraries are shared.4 Platform Security Symbian OS v9. An executable program has three types of binary data: program data. Whenever an application is installed. The only exceptions are EXEs residing in ROM. the program code and read-only data are read directly from ROM. Because Symbian OS DLLs are shared. A capability is a privilege level assigned to every Symbian OS process. This is an optimization to save expensive RAM and improve efficiency. held by the kernel.com as well as the Symbian Developer Library documentation in your SDK for detailed information about UIDs. When a second thread requires the same DLL. every time the program runs it gets new areas of memory allocated for all those three types of data. UID3 uniquely identifies a file. that grants the trust that it will not abuse the services associated with the associated privilege. it is attached to the same copy of the code. Refer to www. Two executables cannot have the same UID3 value. which allocates them from a central database to ensure that each binary has a different value. The security model operates at the software level to detect and prevent unauthorized access to hardware. A DLL resides in the same memory address in all threads that are using it.
~ CMyActive (). The scheduler is executed in non-pre-emptive mode. Active objects must run to completion. CActive is an abstract class with two pure virtual functions. Basically.h.5 Active Objects Symbian OS uses active objects to provide lightweight event-driven multitasking and simplify programming based on asynchronous tasks within a single thread. The base class for active objects is CActive. detect the completion of any task and process the results. . Define functions to create the active object (ConstructL(). there is a loop running that checks if any event of any active object ends. Thus. as well as to use system resources efficiently. You must create a class derived from CActive.NewL()). In what follows you will find details on what active objects are and how to use them. active objects provide ways to make asynchronous requests. private: void ConstructL (). This method corresponds to a RunL() of CActive that each derived class must implement. The scheduler returns to standby mode after the active object performs the response to the event. Also. / / Asynchronous call public: // Declared in CActive // It is executed when the asynchronous call is completed (mandatory) RunL void (). // Call to treat leaves that may occur in RunL (optional) TInt RunError (TInt err). In this case. define the method that represents the asynchronous call. an active object cannot be interrupted in order to switch to another active object. The following snippet defines an active object: 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 CMyActive class: public CActive { public: static CMyActive * NewL (). // Define what to do to cancel a call in progress (required) DoCancel void (). it performs the call to the active object to handle the event. and implement some base class methods that are required for the operation of active objects. RunL() and DoCancel(). TRequestStatus iStatus. Therefore. Register the active object to the active scheduler. the scheduler invokes a method of the active object to warn about this event. InvokeAnyService void (). you must create a class derived from CActive. CMyActive ().Qt Apps and Native Symbian Extensions 103 6. They are used in preference to threads to reduce the overhead whenever context switches occur. } In order to create an active object you must execute the following steps: 1. The active scheduler is a component of the system that manages the implementation of active objects and determines which active object is associated with a given event. To create an active object. 2. defined in e32base.
to set this value to KRequestPending before initiating the asynchronous request. which will be executed upon processing of the asynchronous call. Reset DoCancel(). the scheduler calls the RunL() method of the active object. Before making the call. so that you do not need to do so explicitly. 6. to be able to cancel an asynchronous call that is still in progress. 4. because in practice each active object can have only one request in progress. Submit the request. Reset RunL(). The active object is removed from the scheduler when it is destroyed. which should call the Cancel() class CActive. the method SetActive() must be called to indicate that a request is pending and the object is waiting. Active objects may have priorities for implementation. it is important to check whether there exists some outstanding request. } This call could also be done in ConstructL() or in NewL(). defines the standard values for active objects. The current status of the asynchronous request can . If the request is successful. This property can be used if there are several active objects to be executed. The scheduler of active objects is represented by the class CActiveScheduler. Note that this step is optional. When the processing related to the request finishes. Define the destructor.104 Qt for Symbian 3. 7. by calling ConstructL. A call to CActive::SetActive() indicates that a request has been submitted and is currently outstanding. passing the iStatus member variable of TRequestStatus for the service provider asynchronously. so that all calls may be cancelled if the object is destroyed. redefining the method RunError(). The enumerated type TPriority. Handle exceptions and leaves. 3. a member of the class CActive. 2. Public methods provided in an active object class are used to perform calls that initiate the request to asynchronous service providers. The standard behaviour is as follows: 1. The class constructor CActive requires that a priority is determined so that derived classes must meet this requirement: 1 2 3 CMyActive: CMyActive () : CActive (CActive: EPriorityStandard) {} The method NewL() is responsible for constructing an instance of this object. and objects are registered when you call the static method Add() of this class: 1 2 3 4 5 CMyActive:CMyActive() : CActive (CActive: EPriorityStandard) { CActiveScheduler::Add(this). 5. Define and implement the functions that represent the asynchronous calls. Note that an active object class always implements the pure virtual RunL() method that is inherited from the CActive base class.
such as Aubert (2008). the Qt libraries may access Open C libraries or native Symbian libraries.8 Qt for Symbian 6. Any active object must implement the pure virtual DoCancel() method of the base class in order to terminate a request. CAknDocument and . The method should return KErrorNone if the error has been handled. As illustrated in Figure 6. when you are porting code from other platforms or writing code with real-time requirements.8.6 Error Handling Leaves that occur in RunL() are treated by the method RunError(). the same that was passed to the function in the asynchronous call. defining a handle to a thread. 6. Note that possible errors (panics) might occur when using active objects.2. A thread is created in the suspended state and its execution initiated by calling RThread::Resume(). Thus. you can use threads for multitasking – more specifically. for more details on such a situation as well as on active scheduler behaviour. 6. The Qt port was put on top of native Symbian and Open C libraries. You should be aware that whenever an active object is cancelled.Qt Apps and Native Symbian Extensions 105 be monitored through the field iStatus in the TRequestStatus object of the active object. Threads can be suspended. A call to Kill() or Terminate() normally finishes a thread and you can call Panic() to announce a programming error. and therefore no longer scheduled. the active scheduler will be responsible for handling the error. 6. Note that the thread itself is a kernel object. Open C libraries or even native Symbian libraries. and can be restarted by calling Resume(). by calling RThread::Suspend(). Symbian OS provides the class RThread. The standard entry point of Qt application is the main() function. Refer to the literature. a Symbian Qt application may access Qt libraries. If another value is returned.7 Threads Instead of using active objects. The CActive::Cancel() calls DoCancel() and waits for notification that the request has terminated. including instantiation of objects of the CAknApplication. Also. In order to manipulate threads. This method cannot leave since it can be called in the destructor of the active object. Such exceptions are generated by the active scheduler when a request ends but cannot identify the active object responsible to process it. Threads are scheduled based on a pre-emptive decision mode and threads with the same priority are selected based on a round-robin policy. This implementation should call the appropriate method that cancels a request to the asynchronous service. the method RunL() is not executed. On Qt/Symbian applications the S60Main method implements the E32Main() that initializes the Symbian application UI framework. The parameter represents the error code of the exception.1 Combining Qt and Native C++ The Qt port for Symbian was designed to provide the same level of performance as Avkon on Symbian devices. the method DoCancel() releases resources being used when a cancellation is issued.
Qt for Symbian
Figure 6.2 Qt/Symbian port.
CAknAppUI classes, and the creation of the control environment and active scheduler for the main thread. Finally, the S60Main method also calls the Qt main() function. At the time of writing, the libraries ported to Symbian in the Qt 4.6 release include: QtCore, QtGui (partially), QtNetwork, QtScript, QtSvg, QtTest, QtWebKit and QtXml.
6.8.2 Building Qt Applications in the Symbian Environment
Qt/Symbian projects use the underlying Symbian toolchain, though the projects are built in a different way. First of all, the standard Qt build tools are used as a wrapper around the Symbian tools. This means that the standard Qt project files, such as .prj and .pro, are used instead of Symbian project files. Furthermore, those files are built in the same way as a non-Symbian Qt application, using make and qmake. This integration between Symbian and Qt tool chains is illustrated in Figure 6.3. Developers must first generate project files using the command qmake -project. As occurs for standard Qt applications, this command finds a source code file such as .h, .cpp and .ui in the current directory and builds a .pro file. Then the developer can generate the Makefile from the .pro file using the qmake command. This also generates standard Symbian build items, such as the bld.inf file, .mmp file, _reg.rss default registration file, .mk extension makefiles and .pkg package files. The well-known Makefile also generated by qmake works as a wrapper around the standard Symbian toolchain. When the make command is executed, it calls bldmake and abld to build the Qt application. After executing the make command, and if no compilation errors were found, the binaries files are generated. Using command-line tools may add extra levels of difficulties for some developers. An alternative to those tools is the Carbide.c++ environment. Carbide provides support for project creation, compilation, debug and UI design. To create a new Qt project, click File→New→Qt Project and follow the wizard.
Qt Apps and Native Symbian Extensions
Figure 6.3 Integration of Symbian and Qt toolchain.
6.8.3 Separating Qt and Symbian Implementations
Besides Nokia's efforts to provide full Qt support on its devices, there are still some situations in which it is necessary to use Symbian code in order to access some functionalities of the device. One example is access to the Sensor API, such as the magnetometer API which is not yet directly supported in Qt. The main drawback is that it is necessary to separate the Symbian code explicitly from the Qt code. This is particularly true when the application can be ported to other platforms. In this way, the specific Symbian code can be easily replaced by another platform-specific code through the use of the private implementation (pimpl) pattern. The private implementations can be achieved through wrapper classes. In what follows, we will describe how to access Symbian APIs from Qt using the pimpl pattern. The example program reads data from a magnetometer using an active object and updates the data on the device display using a QLabel data type. The following files are required to execute this simple task: 1. MagnetoWidget.pro – this is the Qt project file that qmake uses to generate the Makefile in order to compile the project. 2. main.cpp – this is the entry point of the Qt application.
Qt for Symbian
3. MagnetoWidget.h and MagnetoWidget.cpp – these are the header and source files of the Qt widget that shows the magnetometer data on the display. 4. AOWrapper.h and AOWrapper.cpp – these are the header and source files of the Qt wrapper that will access platform-specific, in our case Symbian, classes. 5. AOWrapperPrivate.h and AOWrapperPrivate.cpp – these are the header and source files of the Symbian-specific classes that access the Sensor API. The Project File Let us start by showing the MagnetoWidget.pro file which should be modified to specify which are the Qt file classes and the platform-specific file classes. A typical Qt project file looks like the following:
1 2 3 4 5 6 7 8 9
TARGET = MagnetoWidget QT += core \ gui HEADERS += AOWrapper.h \ MagnetoWidget.h SOURCES += AOWrapper.cpp \ MagnetoWidget_reg.rss \ main.cpp \ MagnetoWidget.cpp
The TARGET variable indicates the target application that will be generated. QT is used to specify the Qt libraries that should be compiled with the project. In our case, QtCore and QtGui have been added. Finally, HEADERS is used to specify the headers files and SOURCES is used to specify the source files of the project. In order to support platform-specific classes, the MagnetoWidget.pro file above should be modified by adding a section for the platform files. In our case, MagnetoWidget.pro looks like the following:
1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16
TARGET = MagnetoWidget QT += core \ gui HEADERS += AOWrapper.h \ MagnetoWidget.h SOURCES += AOWrapper.cpp \ MagnetoWidget_reg.rss \ main.cpp \ MagnetoWidget.cpp symbian { TARGET.UID3 = 0xE5D4CBCC HEADERS += AOWrapperPrivate.h SOURCES += AOWrapperPrivate.cpp LIBS += -lsensrvclient \ -lsensrvutil }
Qt Apps and Native Symbian Extensions
Note that the last seven lines have been added. These lines specify which are the Symbianspecific files. Here LIBS specifies which Symbian libraries are required to compile the classes while HEADERS and SOURCES specify the header and source code files. There may be more than one platform-specific section. In this case, the compiler will decide which files should be compiled depending on the target. The Qt Classes The first Qt class is MagnetoWidget, which specifies the widget that will show the magnetometer date on the display. This class inherits from QtWidget and has all the UI elements of our example. Since our example is very simple, and our main purpose is to show how to separate Qt classes from Symbian-specific classes, the UI can be implemented only in the constructor of the MagnetWidget class:
1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19
MagnetoWidget::MagnetoWidget(QWidget *parent) : QWidget(parent) { wrapper = new AOWrapper(this); QGridLayout *layout = new QGridLayout; QLabel *aLabel = new QLabel(this); aLabel->setAlignment(Qt::AlignHCenter); aLabel->setText("Angle From Magnetic North:"); layout->addWidget(aLabel, 0, 0); angle = new QLabel(this); angle->setAlignment(Qt::AlignHCenter); angle->setText(""); layout->addWidget(aLabel, 1, 0); setLayout(layout); connect(wrapper, SIGNAL(angle_changed(int)), angle, SLOT(setText( QInt))); }
On line 3 the active object wrapper is instantiated. The AOWrapper class provides an abstraction of all platform-specific classes for accessing the Sensor API. In this way, if we are developing a program that should run on many platforms, only the AOWrapper class will be referred to by the Qt classes. On line 19, the signal angle_changed is connected to the setText slot of the Qlabel angle in which the value read from the magnetometer is shown. In short, every time the value read from the sensor changes, a signal is sent to the angle QLabel and its text is updated. The rest of the code is usual Qt:
1 2 3 4
class AOWrapper : public QObject { Q_OBJECT
the private classes need to access the signals defined in the public class: 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 /* * AOWrapper constructor */ AOWrapper::AOWrapper(QObject *parent) : QObject(parent) { d_ptr = CAOWrapperPrivate::NewL(this). } /* * AOWrapper destructor */ AOWrapper::~AOWrapper() { delete d_ptr. } The Symbian-Specific Classes The public class is responsible for providing a unique way to access platform resources from the Qt source code. virtual ~AOWrapper(). In our case we have only one platform-specific class: d_ptr allows referring to the private class from the public class. to allow the private class to access its methods. the private classes are declared to be friend classes.110 Qt for Symbian 5 6 7 8 9 10 11 12 13 14 15 16 17 public: // Class constructor and destructor AOWrapper(QObject *parent = 0). is the wrapper used to access the Symbian-specific code. Note that in the class definition above. Now we discuss how to implement the Symbian-specific classes to access the platform resources. signals: // Signals to connect with private classes with UI void angle_changed (int angle). which is used by MagnetoWidget. private: // Friend class definitions friend class CAOWrapperPrivate. private: // Pointer to private classes CAOWrapperPrivate *d_ptr. The public class constructor instantiates the private class object passing itself. using the this operator. a destructor and a pointer to the platform-specific classes. Our example uses the Sensor API to get data from the magnetometer. The AOWrapper class. This is necessary to allow the platform-specific classes to access the methods of the public Qt class. }. This data can be used to implement a number of interesting applications – from a simple compass to a complete . It has a constructor. More specifically.
CAOWrapperPrivate uses the two-phase constructor of Symbian. TTime iAngleFromMagneticNorthTimeStamp. . The specific class. // How to cancel me void DoCancel(). // Two-phase constructor static CAOWrapperPrivate* NewL(AOWrapper *aPublicAPI = 0). private: // Second-phase constructor void ConstructL(). To allow cross-platform implementation. TInt iAngleFromMagneticNorth. and all objects are instantiated using the NewL method. // Two-phase constructor static CAOWrapperPrivate* NewLC(AOWrapper *aPublicAPI = 0). private: // Handle completion void RunL(). public: // Function for making the initial request void StartL(TTimeIntervalMicroSeconds32 aDelay). public: // C++ constructor CAOWrapperPrivate(AOWrapper *aPublicAPI = 0). If the application is being built for more than one platform. it is necessary to have specific private classes for each target platform. This is necessary to allow a constant update of the data read from the sensors. // Cancel and destroy ~CAOWrapperPrivate(). accesses the Sensor API and it should be an active object that inherits from CActive.Qt Apps and Native Symbian Extensions 111 navigation system in which the map rotates on the display depending on the direction the user is moving in. All Symbian-specific code should be implemented in the private class. the source and header files for private class implementations are added to the project based on the platform. The complete definition of the CAOWrapperPrivate class is shown below: 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 class CAOWrapperPrivate : public CActive { public: // Magnetometer data TInt iMagnetometerCalibrationLevel. called CAOWrapperPrivate.
// Find magnetometer sensor channel and open it void CAOWrapperPrivate::FindAndOpenChannel().h and sensrvmagnetometersensor. // Pointer to public implementation // Channels to access magnetometer sensor data CSensrvChannel* iMagnetometerSensor. // Initialized EError // Error condition }. TInt RunError(TInt aError). The constructor also initializes the public attributes. This is also the same for some of the other active object methods: . In order to access the Sensor API the sensrvchannel. NewL and NewLC constructors are implemented as usual and are omitted here. sensrvchannelinfo. // Set calibration level to on/off void CAOWrapperPrivate::setAutoCalibration(bool val). sensrvchannelfinder.h. // Get the calibration level void CAOWrapperPrivate::getCalibrationLevel().h also. The CAOWrapperPrivate constructor receives a pointer to the CAOWrapper public implementation. This pointer is used later to emit a signal indicating that the data read from the sensors has changed. private: TInt iState. // Uninitialized EInitialized. // Get angle from north pole void CAOWrapperPrivate::getAngleFromMagneticNorth(). // State of the active object RTimer iTimer. The magnetometer API requires sensrvmagneticnorthsensor. sensrvtypes. // Provides async timing service AOWrapper *q_ptr. Default implementation causes // the active scheduler to panic.h headers are required. private: enum TAOWrapperPrivateState { EUninitialized.112 Qt for Symbian 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60 61 62 63 64 65 66 67 68 69 70 // Override to handle leaves from RunL().h. CSensrvChannel* iMagneticNorthSensor.h.h and sensrvdatalistener. }.
it always checks the calibration level of the sensor. When the calibration level is good. RunL opens the sensor channels on its first execution using the method FindAndOpenChannel(). } In an active object. automatic calibration is set. iAngleFromMagneticNorth = magNorthData. the data is recovered from the sensor and a signal is emitted (emit q_ptr->angle_changed()): 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 void CAOWrapperPrivate::RunL() { if (iState == EUninitialized) { // In the first run should find and open sensor channels FindAndOpenChannel(). q_ptr(wrapper) // Standard priority { iMagnetometerCalibrationLevel = 0. In our example. and if it is too low. iTimeStamp. if (iMagnetometerCalibrationLevel >= 2) { TSensrvMagneticNorthData magNorthData.Qt Apps and Native Symbian Extensions 113 1 2 3 4 5 6 7 CAOWrapperPrivate::CAOWrapperPrivate(AOWrapper *wrapper) : CActive(EPriorityStandard). From that point on. the RunL method is executed periodically. TPckg<TSensrvMagneticNorthData> magNorthPackage( magNorthData). The frequency it invokes is set by the developer. iMagneticNorthSensor->GetData(magNorthPackage). } else if (iState != EError) { getCalibrationLevel(). iAngleFromMagneticNorthTimeStamp = 0. emit q_ptr->angle_changed(iAngleFromMagneticNorth ). iAngleFromMagneticNorthTimeStamp = magNorthData. } } 16 17 18 19 20 21 22 23 24 25 26 27 28 . } else { // If calibration level is too low. iAngleFromMagneticNorth. iAngleFromMagneticNorth = 0. iState = EInitialized. set auto calibration ON again setAutoCalibration(true).
Instantiate a channel finder object. // Tell scheduler a request is active } Opening a channel requires execution of the following steps: 1. // Set for 1 sec later SetActive(). // Fifty: open the sensor channel // When the channel object is created the channel info object // must be an object returned by CSensrvChannelFinder::FindChannelsL ().iChannelType = KSensrvChannelTypeIdMagneticNorthData. CleanupStack::PushL(iMagnetometerSensor). channelInfo). // Third: create and fill channel search criteria TSensrvChannelInfo channelInfo. it can be opened using the OpenChannelL() method: 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 void CAOWrapperPrivate::FindAndOpenChannel() { // First: construct a channel finder CSensrvChannelFinder* channelFinder. iMagnetometerSensor->OpenChannelL(). CleanupStack::PushL(channelFinder).After(iStatus. 17 18 19 20 21 22 23 24 25 26 27 28 29 . channelFinder = CSensrvChannelFinder::NewL(). // Fourth: find the channel // here we look for the magnetometer channel channelInfo. Once the desired channel is found. 2. Find the channel according to a search criterion.iChannelType = KSensrvChannelTypeIdMagnetometerXYZAxisData.114 Qt for Symbian 29 30 31 iTimer. // Second: list of found channels RSensrvChannelInfoList channelInfoList. 1000000). iMagnetometerSensor = CSensrvChannel::NewL(channelInfoList[0]). setAutoCalibration(true). it is necessary to instantiate a CSensrvChannelFinder object that is used to search for a channel using a criterion specified by a TSensrvChannelInfo object. channelFinder->FindChannelsL(channelInfoList. 3. // Repeat steps 4 and 5 for the compass channel channelInfo. To search for the magnetometer sensor the channel type should be set to KSensrvChannelTypeIdMagnetometerXYZAxisData. and to search for the compass sensor the channel type should be set to KSensrvChannelTypeIdMagneticNorthData. In this way. Open the sensor channel.
} Proceeding as explained above. iMagneticNorthSensor->OpenChannelL(). 6. iMagneticNorthSensor = CSensrvChannel::NewL(channelInfoList[0]).4 Other Issues Error Codes Another issue that developers should handle when building Qt/Symbian applications is the impossibility of mapping Qt error codes to Symbian error codes. Automatic calibration can be set on/off using the method setAutoCalibration(): 1 2 3 4 5 6 7 void CAOWrapperPrivate::setAutoCalibration(bool val) { TSensrvProperty property. KSensrvItemIndexNone. but not system-wide error codes. iMagnetometerSensor->GetPropertyL( KSensrvPropAutoCalibrationActive. This is mainly because Qt provides only class-specific error codes.8. or any other platform-specific classes. you can see that it is possible to separate the Symbian-specific classes. // finder not needed any more } 36 The Sensor API allows automatic calibration of the digital compass. the calibration level can be easily retrieved as shown below in the method getCalibrationLevel(): 1 2 3 4 5 6 void CAOWrapperPrivate::getCalibrationLevel() { TSensrvProperty property. 1 to enable. CleanupStack::PopAndDestroy(channelFinder). from the Qt code. channelInfo).GetValue(iMagnetometerCalibrationLevel).Qt Apps and Native Symbian Extensions 115 30 31 32 33 34 35 channelFinder->FindChannelsL(channelInfoList. iMagnetometerSensor->SetProperty(property). } 8 9 10 11 Finally. Consequently. keeping the code multi-platform. property). The calibration is required to obtain more precise data from the sensors. KSensrvItemIndexNone. CleanupStack::PushL(iMagneticNorthSensor). less effort is required to port it to new targets. property). . 0 to disable autocalibration property. However.SetValue(val). the developer should enable it. property. This isolates the platform-specific issues from the private classes. // set auto-calibration on/off. iMagnetometerSensor->GetPropertyL(KSensrvPropCalibrationLevel. The channel should already be open.
For instance.9 Summary In this chapter we presented basic concepts related to Symbian OS as well as how to access the Symbian API from Qt using the pimpl pattern. Ltd. the private implementation can be used to trap a leaving method and to return such an error code to a pure Qt method that will handle the error. it is also removed from the tree.116 Qt for Symbian When an error occurs in the application. When objects are created in Qt. Symbian applications should make use of the cleanup stack to deallocate objects in the heap when an exception occurs. John Wiley & Sons. Allocating Memory Developing applications for mobile devices requires some caution that is not needed when developing desktop applications. However.. Bibliography Aubert M 2008 Quick Recipes on Symbian OS: Mastering C++ Smartphone Development. If its parent is deleted. private_methodL (<list of args>).). If the application attempts to allocate some memory and there is none available. The only case in which an object is not automatically deleted is if it was created with new and has no parent. This behaviour applies for objects on the heap and for objects on the stack. they are stored in an object tree. return error. The example program reads data from a magnetometer using an active object and updates the data on the device display. then the error code will be trapped and handled somewhere else by showing an error message or by some other action that the developer considers more appropriate. the application is simply closed. If the object is deleted. this is not the scenario in developing for mobile devices. it is added to the object tree as a child of its parent. } If something goes wrong when executing private_methodL(). . 6. then the object is automatically deleted and both are removed from the tree. and this is also true for most Qt applications. in which memory is still a limited resource. TRAPD (error. For this reason. This is also true when building Qt/Symbian applications. This can be implemented with a code such as: 1 2 3 4 5 6 int CAOWrapperPrivate::private_method (<list of args>) { .. memory for personal computers is so cheap that most of the programs are not concerned with how it is used. When an object is created. In this case the object should be explicitly deleted. making possible the automatic deletion of objects that have a parent.
1 Displaying Messaging Accounts The Messaging API allows the listing and manipulation of messaging accounts. This could be performed in the same thread in which the widget's methods run. As stated above. but having a separate thread for the operation results in increased performance and helps prevent an unresponsive UI. All examples can be directly downloaded from the book's web page. The definition of the class is as follows. the reader should check with our book's homepage for recent updates and extensions. Morten V. so selecting an account which is assigned to SMS and sending a text message is practically performed in the same way as selecting an email account and sending an email.7 Qt for Symbian Examples Bertalan Forstner. including a brief summary of their functionalities. There is an inner class definition for Loader. Developers will be able to take a closer look at the available code libraries of Qt and mobile extensions of Qt for Symbian.1. The list of accounts is stored in the member variable QMessageAccountIdList m_ids: 1 2 3 class AccountsWidget : public QWidget { Q_OBJECT . Pedersen and Hassan Charaf This chapter presents some examples of Qt program code for the Qt Mobility API and Qt Mobile Extensions. 7. One of the best things about messaging is that all the different types of messages can be handled via the same API. and obtain design ideas concerning mobile software development using the Qt for Symbian SDK. If we want to send a message via a specific account. which encapsulates a thread responsible for querying the list of messaging accounts.1 Mobility API Examples In the following we will present some examples for the use of Qt Mobility APIs. András Berke. Imre Kelényi. we must first acquire the account's ID. The purpose of these examples is to demonstrate the features of Qt and to introduce Qt programming techniques. The following example widget displays a combo box with a list of the messaging accounts available on the device and emits a signal if the selected account is changed. 7.
void hideEvent(QHideEvent* e). The Loader overrides QThread's default run() implementation and queries the available accounts via the QMessageStore singleton. private: void setupUi(). public: AccountsWidget(QWidget* parent = 0). void loadFinished(). void loadStarted(). }. protected: void showEvent(QShowEvent* e). QString currentAccountName() const. QMessageAccountIdList ids() const.118 Qt for Symbian 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 private: class Loader : public QThread { public: Loader(AccountsWidget* parent). Loader m_loader. private slots: void load(). QMessageAccountId currentAccount() const. bool isEmpty() const { return m_accountsCombo->count() == 0. }. The list of accounts is then passed to the . mutable QMutex m_loadMutex. } signals: void accountChanged(). void setIds(const QMessageAccountIdList& ids). QComboBox* m_accountsCombo. QLabel* m_busyLabel. void run(). private: AccountsWidget* m_parent. private: QStackedLayout* m_stackedLayout. QMessageAccountIdList m_ids.
A mutex is used in the setter and getter for the account IDs to prevent any undesired behaviour due to the multi-threaded execution: 1 2 3 4 5 6 7 8 AccountsWidget::Loader::Loader(AccountsWidget* parent) : QThread(parent).SIGNAL(started()). m_loader(this) { setupUi().this.this. } 9 10 11 12 13 14 15 16 17 18 19 20 21 22 The initialization of the class AccountsWidget is carried out by the constructor and the setupUi() method.SLOT(loadFinished())). m_busyLabel(0). } QMessageAccountIdList AccountsWidget::ids() const { QMutexLocker mutex(&m_loadMutex). m_parent->setIds(ids).SLOT(loadStarted())). m_accountsCombo(0). m_parent(parent) { } void AccountsWidget::Loader::run() { QMessageAccountIdList ids = QMessageStore::instance()-> queryAccounts(). m_ids = ids.SIGNAL(finished()). The UI uses a QStackedLayout and QLabel to hide the combo box and display 'busy text' while the accounts are being loaded. The loader thread's started() and finished() signals are connected to the loadStarted() and loadFinished() slots: 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 AccountsWidget::AccountsWidget(QWidget* parent) : QWidget(parent). connect(&m_loader. } void AccountsWidget::setIds(const QMessageAccountIdList& ids) { QMutexLocker mutex(&m_loadMutex). m_stackedLayout(0).Qt for Symbian Examples 119 AccountsWidget parent. return m_ids. connect(&m_loader. } void AccountsWidget::setupUi() { m_stackedLayout = new QStackedLayout(this). .
. QStackedLayout switches to the busy label to hide the combo box while loading is in progress.%2").name()). } void AccountsWidget::loadFinished() { m_accountsCombo->clear().name()). #endif } 21 22 23 24 25 26 27 28 29 30 31 . } else m_busyLabel->setText("No accounts!"). #endif m_stackedLayout->setCurrentWidget(m_busyLabel).this. and each account name is added to the combo box: 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 void AccountsWidget::loadStarted() { #ifndef _WIN32_WCE setCursor(Qt::BusyCursor). m_accountsCombo->addItem(QString("%1 .arg(account. i < accountIds. ++i) { QMessageAccount account(accountIds[i]). if(!accountIds.SIGNAL(currentIndexChanged(int)).. } 22 23 24 25 When loading the accounts is started. When the loading process has finished. the list of accounts is processed by a loop."). m_busyLabel = new QLabel("Loading. } m_stackedLayout->setCurrentWidget(m_accountsCombo). m_stackedLayout->addWidget(m_busyLabel). SIGNAL(accountChanged())).count().120 Qt for Symbian 18 19 20 21 m_accountsCombo = new QComboBox(this). m_stackedLayout->addWidget(m_accountsCombo). connect(m_accountsCombo.account. #ifndef _WIN32_WCE setCursor(Qt::ArrowCursor).isEmpty()) { for(int i = 0. QMessageAccountIdList accountIds = ids().arg(i +1).
start(). When the widget becomes hidden. QWidget::hideEvent(e). } void AccountsWidget::hideEvent(QHideEvent* e) { if(m_loader.exit(). } QString AccountsWidget::currentAccountName() const { if(m_loader. } . if(m_loader. } return result. return QString(). } 17 18 By overriding the show event handler. return ids().Qt for Symbian Examples 121 The account loading process is started by calling the load() method. the widget can automatically start loading the account list when it is shown.toString(). } Methods are also provided for getting the selected account's ID and name: 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 QMessageAccountId AccountsWidget::currentAccount() const { QMessageAccountId result. QWidget::showEvent(e).isRunning()) m_loader. runonce = true.isFinished() && m_accountsCombo->count()) return m_accountsCombo->itemData(m_accountsCombo-> currentIndex()).at(index). if(!runonce) m_loader. the loader is also disabled if it is running: 1 2 3 4 5 6 7 8 9 10 11 12 void AccountsWidget::showEvent(QShowEvent* e) { load(). which uses a static variable to ensure that querying the accounts is performed only once: 1 2 3 4 5 6 7 void AccountsWidget::load() { static bool runonce = false.isFinished() && m_accountsCombo->count()) { int index = m_accountsCombo->currentIndex().
const QMessageStore:: NotificationFilterIdSet& filter). void messageRemoved(const QMessageId& id. void stateChanged(QMessageServiceAction::State s).1. how to get notifications of when messages are removed or updated. the other can also be obtained. void hideEvent(QHideEvent* e). It demonstrates how to query messages from the system.2 Displaying Recent Messages The following example shows how to create a widget that displays a list of recent messages. unsigned int maxRecent = 10). The displayed list items and the message IDs are tied together via QMap<QMessageId. private: void setupUi(). signals: void selected(const QMessageId& messageId). void messagesFound(const QMessageIdList& result).122 Qt for Symbian 7. void messageUpdated(const QMessageId& id. void processResults(). This ensures that if either the list item or the message ID is present. and how to use QMessageServiceAction to perform messaging-related tasks in general. The list widget shows the subject of the messages and if they are partial messages or not. protected: void showEvent(QShowEvent* e).QListWidgetItem*> m_indexMap and data is stored in each QListWidgetItem with the role MessageIdRole. The class emits the signal selected(const QMessageId& messageId) when a message is selected: 1 2 3 4 5 6 class RecentMessagesWidget : public QWidget { Q_OBJECT public: RecentMessagesWidget(QWidget* parent = 0. const QMessageStore:: NotificationFilterIdSet& filter). void load(). The current state of the message loading process is stored in an instance of the State enum called m_state. QMessageId currentMessage() const. ~RecentMessagesWidget(). QListWidgetItem * previous). private slots: void currentItemChanged(QListWidgetItem* current. 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 . The class definition of the example widget RecentMessagesWidget is as follows. void updateState().
this. //register for message update notifications connect(QMessageStore::instance(). QMap<QMessageId. 7 8 9 10 11 .QListWidgetItem*> m_indexMap. Done }. m_maxRecent(maxRecent). m_layout(0) . unsigned int m_maxRecent.SIGNAL(messagesFound(const QMessageIdList&)).SIGNAL(stateChanged(QMessageServiceAction:: State)). this. QMessageServiceAction* m_service. Two signals of the QMessageStore singleton are also connected to get a notification when one of the messages is removed or updated after they have been added to the UI list. m_service(new QMessageServiceAction(this)). m_state(Unloaded) { setupUi(). LoadFailed. connect(m_service.this. LoadFinished. unsigned int maxRecent) : QWidget(parent). m_statusLabel(0). State m_state. Processing. We are going to use a message service to get the list of messages.SLOT(stateChanged(QMessageServiceAction::State)) ). }.SLOT(messagesFound(const QMessageIdList&))). Message services can be accessed via QMessageServiceAction instances. so it allows all messages. private: QListWidget* m_messageListWidget.Qt for Symbian Examples 123 30 31 private: enum State { Unloaded. This would allow us to get only a subset of all available messages from the messaging store. m_messageListWidget(0). connect(m_service. the constructor connects the signals of the messaging objects to the handler slots.SIGNAL(messageUpdated(const QMessageId&. Loading. const QMessageStore::NotificationFilterIdSet&))). but in this example the filter has no parameters. The messagesFound signal is emitted when a message is found by the query action and the stateChanged signal is emitted when the state of the action changes. QStackedLayout* m_layout. SLOT(messageUpdated(const QMessageId&. QLabel* m_statusLabel. The filter must be unregistered by the widget's destructor: 1 2 3 4 5 6 RecentMessagesWidget::RecentMessagesWidget(QWidget* parent. in our case the member variable m_service. QMessageStore::NotificationFilterId m_storeFilterId. QMessageIdList m_ids. const QMessageStore::NotificationFilterIdSet&)). static const int MessageIdRole = Qt::UserRole + 1. The last line of the constructor creates and registers a filter for querying the messages. 32 33 34 35 36 37 38 39 40 41 42 43 44 After setting up the UI.
The slot stateChanged() allows us to check if the service action fails or if it has completed successfully and all messages have been processed. } void RecentMessagesWidget::setupUi() { m_layout = new QStackedLayout(this).SIGNAL(messageRemoved(const QMessageId&. m_statusLabel->setFrameStyle(QFrame::Box). QListWidgetItem*))).SLOT(currentItemChanged(QListWidgetItem*. m_statusLabel = new QLabel(this). } 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 Querying the messages is started by the load() method. this.clear().m_maxRecent)) m_state = LoadFailed. connect(m_messageListWidget. } RecentMessagesWidget::~RecentMessagesWidget() { QMessageStore::instance()->unregisterNotificationFilter( m_storeFilterId). the messagesFound() slot stores the message's ID in an array. The passed QMessageOrdering::byReceptionTimeStamp(Qt::DescendingOrder) ensures that the messages are returned. ordered by their timestamp. const QMessageStore::NotificationFilterIdSet&))). m_statusLabel->setAlignment(Qt::AlignHCenter | Qt::AlignVCenter). m_storeFilterId = QMessageStore::instance()-> registerNotificationFilter(QMessageFilter()). which issues the service action. These events are handled by the method updateState(): 1 2 3 4 5 void RecentMessagesWidget::load() { m_ids. const QMessageStore::NotificationFilterIdSet&)). else 6 7 .SIGNAL(currentItemChanged( QListWidgetItem*. m_layout->addWidget(m_messageListWidget). if(!m_service->queryMessages(QMessageFilter(). this. m_messageListWidget = new QListWidget(this).QMessageOrdering:: byReceptionTimeStamp(Qt::DescendingOrder). When a message is found. SLOT(messageRemoved(const QMessageId&. m_layout->addWidget(m_statusLabel).QListWidgetItem*)).124 Qt for Symbian 12 13 connect(QMessageStore::instance().
but the font of the list entry also indicates if the message is a partially or fully downloaded message. id. Only the subject of the messages is displayed. } break. m_layout->setCurrentWidget(m_statusLabel). When loading the messages has been completed. updateState().").Qt for Symbian Examples 125 8 9 10 11 12 13 14 15 16 17 18 19 20 m_state = Loading. it starts processing them by calling processResults()).. which puts the messages into the list widget. } void RecentMessagesWidget::stateChanged(QMessageServiceAction::State s) { if(s == QMessageServiceAction::Failed) m_state = LoadFailed. case Loading: { m_statusLabel->setText("Loading.isEmpty()) { .append(ids). } break. case LoadFinished: { if(m_ids.. } 21 22 23 24 The updateState() method is responsible for updating the child widgets according to the state of the messaging query action. m_layout->setCurrentWidget(m_statusLabel). Note that newItem->setData(MessageIdRole. else if(s == QMessageServiceAction::Successful && m_state != LoadFailed) m_state = LoadFinished. } void RecentMessagesWidget::messagesFound(const QMessageIdList& ids) { m_ids.toString()) is used to store the message ID in the list item's data model so that it can be obtained when the widget is selected in the UI: 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 void RecentMessagesWidget::updateState() { switch(m_state) { case Unloaded: { m_statusLabel->setText(QString()).
"). } break.id.setItalic(isPartialMessage). QMessage message(id).toString()).find(message. newItem->setFont(itemFont). itemFont.takeFirst(). processResults(). newItem->setData(MessageIdRole. bool isPartialMessage = !message.bodyId()). updateState(). } else { m_state = Processing. #endif } void RecentMessagesWidget::processResults() { if(!m_ids. else setCursor(Qt::ArrowCursor). } #ifndef _WIN32_WCE if(m_state == Loading || m_state == Processing) setCursor(Qt::BusyCursor). isContentAvailable(). 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60 61 62 63 64 . break. } } break. m_layout->setCurrentWidget(m_statusLabel) . case Processing: m_layout->setCurrentWidget(m_messageListWidget). QFont itemFont = newItem->font(). No messages. m_layout->setCurrentWidget(m_statusLabel). m_messageListWidget->addItem(newItem).isEmpty()) { QMessageId id = m_ids. subject()).126 Qt for Symbian 21 22 m_statusLabel->setText("Finished. QListWidgetItem* newItem = new QListWidgetItem(message. case LoadFailed: { m_statusLabel->setText("Load failed!").
itemFont. These update the list by either removing or updating the list entry for the given message: 1 2 3 4 5 6 7 8 9 10 11 12 void RecentMessagesWidget::messageUpdated(const QMessageId& id.contains(m_storeFilterId) || m_state == Loading || !id .contains(id)) return. item->setFont(itemFont). } else { m_state = Done. updateState().newItem).find(message. } } void RecentMessagesWidget::messageRemoved(const QMessageId& id. } } After querying the messages has been done and listing them in the list widget. const QMessageStore::NotificationFilterIdSet& filter) { if(!filter. m_messageListWidget->update(). if(item) { int row = m_messageListWidget->row(item).SLOT(processResults())). QListWidgetItem* item = m_indexMap.Qt for Symbian Examples 127 65 66 67 68 69 70 71 72 73 74 m_indexMap.isValid() || !m_indexMap. if(item) { QMessage message(id). const QMessageStore::NotificationFilterIdSet& filter) { if(!filter. it is still possible that one of them is updated or removed. 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 . This is why the messageUpdated() and messageRemoved() slots were connected in the constructor.value(id).contains(id)) return. QFont itemFont = item->font().value(id). isContentAvailable().insert(id. //update the pertinent entry to reflect completeness QListWidgetItem* item = m_indexMap.bodyId()).isValid() || !m_indexMap. QTimer::singleShot(100. bool partialMessage = !message.this.contains(m_storeFilterId) || m_state == Loading || !id .setItalic(partialMessage).
} void RecentMessagesWidget::hideEvent(QHideEvent* e) { if(m_state == Loading || m_state == Processing) { .remove(id). } To allow further use of the widget besides displaying a list of the subjects of the most recent messages. return result. a signal is emitted when one of them is selected. toString()). } QMessageId RecentMessagesWidget::currentMessage() const { QMessageId result. QWidget::showEvent(e). m_indexMap. } 12 13 14 15 The widget's load and hide event handlers ensure that loading of the messages is started when the widget becomes visible and stopped when it goes out of sight: 1 2 3 4 5 6 7 8 9 10 11 12 13 14 void RecentMessagesWidget::showEvent(QShowEvent* e) { if(m_state == Unloaded) load(). QListWidgetItem*) { if(m_state != Processing || m_state != Loading) emit selected(currentMessage()). } m_ids.128 Qt for Symbian 28 29 30 31 32 33 QListWidgetItem* item = m_messageListWidget->takeItem(row ). The ID of the selected message can also be accessed by currentMessage(): 1 2 3 4 5 6 7 8 9 10 11 void RecentMessagesWidget::currentItemChanged(QListWidgetItem*. display the body of the selected message. if(QListWidgetItem* currentItem = m_messageListWidget-> currentItem()) result = QMessageId(currentItem->data(MessageIdRole). updateState(). Another widget can connect to the signal and. for instance. delete item.removeAll(id).
We will also show how we can use the service framework to register and discover our new service on the Symbian device.1. m_ids. QServiceContext* context. 14 15 16 As seen in the above listing. This function is called by the . The service framework will interact with our service though the plug-in interface. class HelloWorldPlugin : public QObject. For more information on the service framework you should consult the Qt Mobility documentation. public QServicePluginInterface { Q_OBJECT Q_INTERFACES(QtMobility::QServicePluginInterface) public: QObject* createInstance(const QServiceInterfaceDescriptor& descriptor . To demonstrate that our new service can be found on the device. }.h: 1 2 3 4 5 6 7 8 9 10 11 12 13 #include <QObject> #include <QServicePluginInterface. The listing below shows the interface declaration from helloworldplugin.Qt for Symbian Examples 129 15 16 17 18 19 20 21 m_service->cancelOperation(). First we must define a plugin interface using the QServicePluginInterface class. However. QAbstractSecuritySession* session). we must implement the pure virtual factory function createInstance() from QServicePluginInterface. } QWidget::hideEvent(e). m_state = Unloaded. The example shown here will only cover a small part of the functionalities available in the service framework.clear().3 Service Framework In this section we will demonstrate the functionality of the service framework by developing a simple 'helloworld' service example. you can use the ServiceBrowser example found in the Mobility API examples folder.h> using namespace QtMobility. Creating a Service Plug-in The first step we need to perform is to create our service plug-in code. it demonstrates the most fundamental functionality needed to develop new service plug-ins. } 7.
The next step is to define the actual plug-in behaviour in the HelloWorld class.h" HelloWorld::HelloWorld(QObject *parent) : QObject(parent) 1 2 3 4 5 6 . However.h" QObject* HelloWorldPlugin::createInstance(const QServiceInterfaceDescriptor& /*descriptor*/. The parameters of the createInstance() function will allow us to support.h> #include <QAbstractSecuritySession. } Q_EXPORT_PLUGIN2(serviceframework_helloworldplugin. }. multiple service implementations in a single plug-in and to check whether the client has sufficient permissions to load the plug-in. for example.cpp): 1 2 3 4 5 6 7 8 #include <QServiceInterfaceDescriptor.130 Qt for Symbian service framework to instantiate our plug-in. HelloWorldPlugin) 9 10 11 12 13 14 15 The Q_EXPORT_PLUGIN2(targetname. #include <QtCore> #include "helloworld. QServiceContext* /*context*/. QAbstractSecuritySession* /* session*/) { return new HelloWorld(this).h" #include "helloworld. public slots: void sayHello(). The following listings show the implementation of the class declaration and definition: 1 2 3 4 5 6 7 8 9 10 11 #include <QObject> class HelloWorld : public QObject { Q_OBJECT public: HelloWorld(QObject *parent = 0). in this example we ignore the parameters passed and simply return a new instance of our 'helloworld' plug-in as shown in the listing below (defined in helloworldplugin.h> #include <QServiceContext.h> #include "helloworldplugin. pluginname) macro exports the plug-in class targetname for the plug-in specified by pluginname. We have now implemented the necessary plug-in handling code. The value of pluginname should correspond to the TARGET specified in the service plug-in's project file as we will see later.
This allows the service framework to use the Qt meta-system to detect which function can be invoked in our plug-in. in this case the sayHello() function. Our plug-in code must be derived from QObject and we must implement the functions invoked by the service framework using the Qt signal and slot mechanism. Now we define the project file.Qt for Symbian Examples 131 7 8 9 10 11 12 13 { } void HelloWorld::sayHello() { qDebug() << "Hello World :)".path = $$QT_PLUGINS_BASE_DIR DEPLOYMENT += pluginDep TARGET.pro file is shown in the Listing below: 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 TEMPLATE = lib CONFIG += plugin INCLUDEPATH += C:\Qt\qt-mobility-src-1.0.sources = serviceframework_helloworldplugin.EPOCALLOWDLLDATA = 1 } Note that we are linking against QtServiceFramework_tp.h SOURCES += helloworldplugin.0-tp\src\serviceframework HEADERS += helloworldplugin. The . You should now be able to build the plug-in using your preferred Qt for Symbian IDE.cpp TARGET = serviceframework_helloworldplugin CONFIG += mobility MOBILITY = serviceframework LIBS += -lQtServiceFramework_tp symbian { load(data_caging_paths) pluginDep.dll pluginDep. since we are using the technology preview of the service framework. Also note that you first have to make sure that you have a built version of the Service Framework Library supplied in the Qt Mobility API .h SOURCES += helloworld. the actual plug-in code is very simple and for it to work we only have to fulfil a few rules.cpp HEADERS += helloworld. } As seen above. where _tp is appended. which will tell the Qt build system how to build our plug-in.
we can just simply right-click on the form and select the option Lay out/Lay out in a grid. Let us assume that our task is to create a simple form named MyMoviesForm. The main advantage of creating the UI in this way is that in this case we can focus the source code on program functionality. After installing this server and our new service plug-in on our device. Further. In that case.6. and a checkbox. e.c++ 2.0.132 Qt for Symbian source package. This could be useful.g. The XML file for the 'helloworld' plug-in can be found in the service_installer_helloworld folder of the example source code. which the user could use to recommend watching the film. we can use the Build Project command from the Project menu to generate the code that describes the form's UI exactly as designed . developers might want to use the extensions in order to be more flexible.2 IDE and Qt for Symbian release 4.2 Qt for Symbian and Mobile Extension Examples Now we look at the mobile extension examples. a button to add a new movie with the given details. However. when we are working on a mobile client application of a movie ranking site. therefore you first need to build and install the service framework server before you can use the application on a device. Our next task is to customize some of the widgets' properties like the shown text.0. This folder also contains a small Symbian application needed to register the our 'helloworld' service on the device. we just have to drag and drop the widget items from the widgets box and arrange them in a layout.com/qtmobility-1. messaging. a group of radio buttons to let the user specify the language of the movie. The registration phase is a little different on the Symbian platform than for other platforms and is documented here: http://doc. on which the user could provide information about recently seen movies. and another one to remove any of the previously added list items. the title of the window or the C++ name of the widget instance. networking. 7. After all the necessary modifications. We can easily perform this using the Qt C++ Property Editor. by instantiating widget and layout items and linking them in the desired way. we need a list of the movies already added. The examples cover the basics of Qt. As you might have read in a previous chapter.1 Basic Widgets Example The first example demonstrates how the standard Qt widgets can be arranged on a simple GUI to realize some basic input functionality. we could just use the Qt Designer Editor in Carbide.html. audio. in all the examples of this chapter we will follow the first way. All of these small demonstration programs were implemented and tested using the Carbide. This is done by adding a service description file in XML to the service manager running on our device. 7.2. it is also possible to create the form manually in program code. a camera and localization. XML and Symbian-specific features such as sensors.trolltech.c++. we still need to make the service framework discover our new plug-in.0-tp/ service-framework-on-symbian. After adding all the necessary widget items. Even though there are Mobility APIs available. Using this command simplifies the arrangement of form items (see Figure 7. To build an input form as described. On Symbian the service framework will run as a server. Our form will contain some simple input fields. a line edit widget for entering the title of the movie.1).
isEmpty()) MyMoviesFormClass->setObjectName( QString::fromUtf8("MyMoviesFormClass")).cpp) is as follows: 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 QT_BEGIN_NAMESPACE class Ui_MyMoviesFormClass { public: QWidget *centralwidget. void setupUi(QMainWindow *MyMoviesFormClass) { if (MyMoviesFormClass->objectName(). QRadioButton *radioEng.1 Illustration of Qt Designer's auto layout function. QRadioButton *radioHun. QLabel *lblTitle. QGridLayout *gridLayout. QCheckBox *chkRecommend. . QPushButton *btnAdd. The listing of the source code for the generated class (naming schema: Ui_<name_of_the_main_widget>Class. QLineEdit *editTitle. QListWidget *listMovies. with the Qt tool. QPushButton *btnClear. QStatusBar *statusbar. QMenuBar *menubar.Qt for Symbian Examples 133 Figure 7. centralwidget = new QWidget(MyMoviesFormClass).
21)). MyMoviesFormClass->setMenuBar(menubar). 1. radioEng = new QRadioButton(centralwidget). radioHun->setObjectName(QString::fromUtf8("radioHun")). chkRecommend->setObjectName(QString::fromUtf8("chkRecommend")). editTitle->setObjectName(QString::fromUtf8("editTitle")). gridLayout = new QGridLayout(centralwidget). editTitle = new QLineEdit(centralwidget). statusbar->setObjectName(QString::fromUtf8("statusbar")). 2. lblTitle = new QLabel(centralwidget). 1. 6. gridLayout->addWidget(radioHun. 1). gridLayout->setObjectName(QString::fromUtf8("gridLayout")). radioHun = new QRadioButton(centralwidget). radioEng->setChecked(true). btnAdd = new QPushButton(centralwidget). 1). radioEng->setObjectName(QString::fromUtf8("radioEng")). 3. 4. gridLayout->addWidget(btnClear. listMovies->setObjectName(QString::fromUtf8("listMovies")). 1. menubar->setGeometry(QRect(0. MyMoviesFormClass->setCentralWidget(centralwidget). gridLayout->addWidget(btnAdd. 0. 262. 2). 2. menubar = new QMenuBar(MyMoviesFormClass). 2). 1. 0. gridLayout->addWidget(radioEng. listMovies = new QListWidget(centralwidget). btnClear->setObjectName(QString::fromUtf8("btnClear")). btnClear = new QPushButton(centralwidget). gridLayout->addWidget(chkRecommend. gridLayout->addWidget(listMovies. 2). . gridLayout->addWidget(editTitle. 1. 0. gridLayout->addWidget(lblTitle. 0. 0. 1. 5. 1. statusbar = new QStatusBar(MyMoviesFormClass).134 Qt for Symbian 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60 61 62 63 64 65 66 67 68 69 70 71 72 73 74 centralwidget->setObjectName( QString::fromUtf8("centralwidget")). 1. 2). 1. 2). menubar->setObjectName(QString::fromUtf8("menubar")). 0. chkRecommend = new QCheckBox(centralwidget). 0. btnAdd->setObjectName(QString::fromUtf8("btnAdd")). lblTitle->setObjectName(QString::fromUtf8("lblTitle")). 2). MyMoviesFormClass->setStatusBar(statusbar). 0. 0. 1.
0. chkRecommend->setText( QApplication::translate("MyMoviesFormClass". "Recommended for watching". radioHun->setText(QApplication::translate("MyMoviesFormClass". } // retranslateUi }. 0.h 1 2 3 4 #include <QtGui/QMainWindow> //including the generated layout header #include "ui_MyMoviesForm. lblTitle->setText( QApplication::translate("MyMoviesFormClass". radioEng->setText(QApplication::translate("MyMoviesFormClass". } // setupUi void retranslateUi(QMainWindow *MyMoviesFormClass) { MyMoviesFormClass->setWindowTitle( QApplication::translate( "MyMoviesFormClass".h" . " Hungarian". btnAdd->setText(QApplication::translate("MyMoviesFormClass".Qt for Symbian Examples 135 75 76 77 78 79 80 81 82 83 84 85 86 87 retranslateUi(MyMoviesFormClass). Note that in the rest of the examples of this chapter we will dispense with listing the generated UI header source code. " Title:". QApplication::UnicodeUTF8)). 0. one named setupUi (called by the MyMoviesForm widget's constructor in order to lay out the enclosed widget items) and the other retranslateUi (called by the UI class itself). "Add to list". " English". QApplication::UnicodeUTF8)). Q_UNUSED(MyMoviesFormClass). the UI class consists of two functions. in most cases we will assume that such a header file exists. " Clear list". QApplication::UnicodeUTF8)). 0. QApplication::UnicodeUTF8)). we can look at the declaration of the MyMoviesForm widget: MyMoviesForm. QApplication::UnicodeUTF8)). QMetaObject::connectSlotsByName(MyMoviesFormClass). 0. } // namespace Ui QT_END_NAMESPACE 88 89 90 91 92 93 94 95 96 97 98 99 100 101 102 103 104 As you may have noticed. 0. After studying the UI source code. However. QApplication::UnicodeUTF8)). "My Movies". 0. btnClear->setText(QApplication::translate("MyMoviesFormClass". namespace Ui { class MyMoviesFormClass: public Ui_MyMoviesFormClass {}. QApplication::UnicodeUTF8)).
//Qmake will do that automatically. ~MyMoviesForm(). private slots: void on_btnAdd_clicked(). Finally. }. //connecting: btnClear pressed -> clear list connect(ui. and the declaration of a private slot called on_btnAdd_clicked().h" MyMoviesForm::MyMoviesForm(QWidget *parent) : QMainWindow(parent) { //calling the previously mentioned setupUi() function ui. Hence. The reason for this naming method is that Qt can detect the slot declaration named on_<widget_name>_<widget_signal_name>() and it connects the particular signal automatically to this specially named slot. Its declaration consists of the standard constructor/destructor methods. there is no need to call Qt's connect() method in source code.setupUi(this). here is the implementation of MyMoviesForm: 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 #include "MyMoviesForm. which we are going to use for implementing the click event handler function for the Add button.136 Qt for Symbian 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 class MyMoviesForm : public QMainWindow { Q_OBJECT public: MyMoviesForm(QWidget *parent = 0). private: Ui::MyMoviesFormClass ui. } void MyMoviesForm::on_btnAdd_clicked() { //btnAdd clicked.listMovies. which means that it is responsible for providing a framework for building the application's UI. the previously mentioned UI class. The class MyMoviesForm is derived from QMainWindow. SIGNAL(clicked()). SLOT(clear())). ui.btnClear. //adding new item to the listwidget if there's any . //No need for connecting Add button's clicked() signal to //on_btnAdd_clicked() private slot explicitly.
and connect the 'Clear list' button's clicked() signal to the list's clear() slot. } } MyMoviesForm::~MyMoviesForm() { } In the source code above we have implemented the window's constructor function.2.2 Background Worker Class The following example will demonstrate how to use Qt's signals and slots mechanism to design and implement a communication interface between your UI widgets and business logic classes. In consideration of the purpose of this demonstration. and then makes the result available to its caller as a QString object: 1 2 3 #ifndef MYWORKERCLASS_H_ #define MYWORKERCLASS_H_ . creates its string representation and adds the string to the list as a new item. QString lang = ui. Its functionality is quite simple: it gathers the information that the user has provided using the input widget items. ui.2 you can see what the layout of the widget example application would look like when running on a mobile device.isEmpty()) { QString title = ui. ui. the worker class will implement only a very simple functionality: it takes an integer as an input parameter and raises it to the second. in which we call the UI arranger function. By connecting these entities.listMovies->addItem( title + " (" + lang + ")" + recommend). we achieve our aim that all the list items will be deleted on the button click event.editTitle->text(). you can find the implementation of the click event handler slot. The source code basically consist of two classes: a QMainWindow object.editTitle->text().radioEng->isChecked() ? QString("ENG") : QString("HUN"). which is responsible for building the UI and handling user input.Qt for Symbian Examples 137 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 if(!ui. and an additional Qt object called MyWorkerClass.editTitle->setText(""). 7. Below the constructor method. In Figure 7.chkRecommend->isChecked() ? QString(" *") : QString(""). third and fourth power. QString recommend = ui. which will implement the business method of this demo application.
#endif /* MYWORKERCLASS_H_ */ The MyWorkerClass declaration consists of standard constructor/destructor functions. void onError(int errCode).2 The widget example running on the Symbian emulator. public slots: void doWork(int param). signals: void onFinished(const QString& result). in order to start the processing of the given input value. }. . const static int ERROR_NOT_A_POSITIVE_NUMBER=1.138 Qt for Symbian Figure 7. 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 #include <QObject> #include <QString> class MyWorkerClass : public QObject { Q_OBJECT public: MyWorkerClass(QObject* = 0). and a public slot named doWork() which may be attached to a signal or simply called directly by the UI class. virtual ~MyWorkerClass(). an integer constant used as an error code value.
the worker class can notify its caller if any exception occurs during processing (which.Qt for Symbian Examples 139 Further. If an invalid parameter was given.h> MyWorkerClass::MyWorkerClass(QObject* parent) : QObject(parent) {} MyWorkerClass::~MyWorkerClass() {} void MyWorkerClass::doWork(int param) { //class business functionality if(param<1) { //input is 0 or negative --> emitting error signal emit onError(ERROR_NOT_A_POSITIVE_NUMBER). } else { //processing input QString retval=QString::number(param). and the second named onError(). the next step is to design a QMainWindow UI class consisting of Qt widgets able to offer a testing environment for the previously presented calculator functionality.i++) { retval+=". Note that the accessibility of signals as opposed to slots cannot be controlled by the developer. in this case. The implementation of the worker class follows: 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 #include "MyWorkerClass. passing the result string emit onFinished(retval). could only be an error caused by an invalid input parameter). "+QString::number(pow(param.h" #include <math. in order take advantage of using Qt's signals and slots mechanism. After implementing the background working class. The UI design of this class might look like that described in Table 7.1. Following this design. It is important to declare the class as a QObject class. for(int i=2. this class also declares two signals.i<5.i)). it emits the onError() signal without calculating the result or emitting any other signal. passing the string value as a result. emitted only in the case of a processing error. } } As previously mentioned. all the signals are public and therefore available for connecting to any QObject's slot. . and in the case of success it emits the onFinished() signal. and to use the Q_OBJECT directive as well. } //finished. one named onFinished(). emitted when the processing is over. the doWork() method implements the processing of the input parameter.
h" class WorkerClassExample : public QMainWindow { Q_OBJECT public: WorkerClassExample(QWidget *parent = 0). private: Ui::WorkerClassExampleClass ui. as listed above in the source code for the Qt window of this example: 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 #ifndef WORKERCLASSEXAMPLE_H #define WORKERCLASSEXAMPLE_H #include <QtGui/QMainWindow> #include "MyWorkerClass.1 UI design of the worker class example. the source code describing the UI is always generated by the IDE. . ~WorkerClassExample(). so there is no need to construct the desired layout by writing its source code.h" //including the generated layout header #include "ui_WorkerClassExample. //worker class instance MyWorkerClass *workerClass. QLabel QLineEdit editValue QPushButton btnGet QLabel QLabel lblResults Spacer Shows 'Value:' string Input value Starts calculation Shows 'Results:' string Shows result value For layout alignment purposes outcome As mentioned in the first example of this chapter.140 Qt for Symbian Table 7. It is only necessary to include the generated UI header file and declare an instance of it as a variable.
if(error==MyWorkerClass::ERROR_NOT_A_POSITIVE_NUMBER) . Finally. Note that no slot is declared in the window class for the worker class onFinished() signal. } void WorkerClassExample::on_btnGet_clicked() { //slot direct method call workerClass->doWork(ui. //connecting the workerclass signals connect(workerClass. SLOT(setText(const QString& ))). here is the implementation of the WorkerClassExample window: 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 #include "WorkerClassExample.editValue->text(). //instantiate workerclass workerClass = new MyWorkerClass(this). connect(workerClass. void on_btnGet_clicked().toInt()).h" WorkerClassExample::WorkerClassExample(QWidget *parent) : QMainWindow(parent) { ui. which will be connected to the worker class onError() signal. SIGNAL(onFinished(const QString&)). SLOT(onWorkerError(int))).setupUi(this). The reason for this is because the signal will be connected directly to the label widget's setText() slot. and on_btnGet_clicked(). which – as previously mentioned – will be connected automatically by Qt to the btnGet button widget's clicked signal.lblResults . this . #endif // WORKERCLASSEXAMPLE_H Apart from the standard constructor/destructor methods.Qt for Symbian Examples 141 24 25 26 27 28 29 30 31 private slots: void onWorkerError(int error). SIGNAL(onError(int)). the WorkerClassExample window declares two slots: onWorkerError(). } void WorkerClassExample::onWorkerError(int error) { //showing error message instead of the result value QString errStr("Unknown"). }. ui.
Qt for Symbian
Figure 7.3 The worker class example running on the Symbian emulator.
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errStr=QString("Not a positive number."); ui.lblResults->setText("Error: "+errStr); } WorkerClassExample::~WorkerClassExample() {}
Figure 7.3 shows how the worker class example application would behave when running on a mobile device.
7.2.3 Bouncing Ball
The following 'bouncing ball' example will introduce to you the Qt Graphics Library and use of the QTime class. It also demonstrates how overriding some of the QWidget's functions can be used to get notifications about key events. You might already be familiar with the 'bouncing ball' demo application. It displays a filled circle moving constantly within the bounds of a window, which is actually a single QWidget descendant. To implement such behaviour, we override the QWidget::paintEvent() protected method, which will be called when the framework asks the widget to repaint itself. When this event occurs, the contents of the widget have already been erased, so we can draw on the blank surface of the widget itself. To draw the desired shapes, we can use the services of the QPainter class. This object is responsible for implementing all the low-level drawing functions, including drawing different kinds of shapes, manipulating the drawing parameters and setting up matrix transformations. To paint a moving ball, we modify the drawn shape's position and repaint the container widget repetitively. We can easily achieve this using Qt's QTimer class. By connecting a timer's timeout() signal – which will be emitted at constant intervals – to the widget's update() slot, we can ensure that the window will be repainted periodically. In the following example we will realize the bouncing ball application in the way explained above; in addition to implementing some supplementary user input handling functions, to demonstrate Qt's key event handling approach, we will make the ball movable by pressing the direction keys as well.
Qt for Symbian Examples
Figure 7.4 Screenshot of the bouncing ball example.
We can accomplish this by overriding the QWidget::keyPressEvent() method and changing the position of the ball by a constant distance depending on the direction key chosen. The header file and the implementation of the described Qt application called BallExample are listed below; the ball painted on the widget's surface is shown in Figure 7.4: BallExample.h:
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#ifndef BALL_H #define BALL_H #include #include #include #include #include #include #include #include #include <QtGui/QWidget> <QTimer> <QPaintEvent> <QPainter> <QColor> <QTime> <QRect> <QPoint> <QString>
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//including the generated layout header //the UI consists of a single full-screen QWidget #include "ui_Ball.h" class BallExample : public QWidget { Q_OBJECT public: BallExample(QWidget *parent = 0); ~BallExample(); protected: void paintEvent(QPaintEvent* event); void keyPressEvent (QKeyEvent * event); private: Ui::BallClass ui; QTimer* timer; //the ball's properties QPoint r; //position QPoint v; //velocity const int D; //diameter }; #endif // BALL_H
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#include "BallExample.h" BallExample::BallExample(QWidget *parent) : QWidget(parent), D(100) { ui.setupUi(this); //initialize timer, and connect it to the widget's update slot //calling update forces the widget to repaint itself timer = new QTimer(this); connect(timer, SIGNAL(timeout()), this, SLOT(update())); //start emitting timer->start(50); //initialize the ball's properties r.setX(this->width() / 2); r.setY(this->height() / 2); v.setX(10);
Qt for Symbian Examples
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v.setY(10); } BallExample::~BallExample() { } void BallExample::paintEvent(QPaintEvent* event) { //move ball r+=v; if(r.x() < 0) { r.setX(0); v.setX(-v.x()); } else if(r.x() > width()-D) { r.setX(width()-D); v.setX(-v.x()); } if(r.y() < 0) { r.setY(0); v.setY(-v.y()); } else if(r.y() > height()-D) { r.setY(height()-D); v.setY(-v.y()); } //draw ball in its new position QPainter painter(this); QColor color(255, 0, 0); painter.setBrush(color); painter.setPen(color); painter.setRenderHint(QPainter::Antialiasing); painter.translate(r.x(),r.y()); painter.drawEllipse(0,0,D,D); } void BallExample::keyPressEvent(QKeyEvent * event) { //handling keypress event //the direction keys move the ball in addition to //moving caused by timer events
if(key == Qt::Key_Left) r+=QPoint(-40. else if(key == Qt::Key_Right) r+=QPoint(40. it will be added to the menu bar of the Qt window. .2 UI design of the softkey example. This means that the menu items will be displayed only if the corresponding line editor focuses on the input. which is actually shown as the softkey menu on the Symbian mobile platform. In our demo application the softkey menu will be made context sensitive. ' string Destination text box For layout alignment purposes outcome 68 69 70 71 72 73 int key=event->key().146 Qt for Symbian Table 7.-40). The Qt approach for handing various sets of input . In order to realize a more user friendly environment. However. as the following program code demonstrates. Selecting the 'cut' menu item will result in clearing the first text box's content and copying it to a private string variable. In our case. QLabel QLineEdit editCut QLabel QLineEdit editPaste Spacer Shows 'Cut . it might not be the best idea to display all the necessary fields on the tiny screen that mobile devices often have. else if(key == Qt::Key_Up) r+=QPoint(0. all the program functionality can be reached. you might look at the declaration file of the softkey demo application.0). In the following demonstration we take a brief look at the method of creating softkey menu items and change their behaviour dynamically. which provides a general UI action handled by menus and toolbars.2.0). Note that the widget itself does not contain any command buttons. There menu items are represented as instances of the QAction class.40). applications could use the device's softkey menu to display command actions as simple menu items. ' string Source text box Shows 'And . The UI design of the example is presented in Table 7. The example itself is a Qt form consisting of two line editors. . The 'paste' menu item will be responsible for inserting the stored string value into the second text editor. } 7. The menu items will implement some basic cut and paste functionality.4 Options Menu Mobile applications often have to deal with a complex UI containing many input widgets and command buttons. else if(key == Qt::Key_Down) r+=QPoint(0. .2. . At first.
QEvent *event). the event filter method will handle only the FocusIn event of the two line editors. the handled event will be 'filtered out'. This behaviour can be achieved by setting the corresponding QAction's enabled Boolean property to 'true' and the other ones to 'false'. . ~Softkeys(). //focus handling filter bool eventFilter(QObject *obj. private: Ui::SoftkeysClass ui. will not be passed to any other registered event filter. Otherwise. After this brief summary of Qt's input handling. If your reimplementation of the event filter method returns true. void pasteEditor(). you could just pass it to the filter method of the parent class. This means that programmers can handle certain events by overriding the parent widget's eventFilter(QObject*. if you were not going to handle a certain event. we list below the header file and the implementation of the Qt application that realizes the previously described cut and paste functionality: Softkeys.e. //represents the clipboard QString clipboard. QEvent*) method and implement the desired functionality based on the received parameters. in order to decide which item will be shown in the options menu bar of the device. //cut & paste functionality void cutEditor(). //menu actions QAction* cutAction.h" class Softkeys : public QMainWindow { Q_OBJECT public: Softkeys(QWidget *parent = 0).Qt for Symbian Examples 147 events (including focus changes) is the use of the filter pattern. i. In our case. which identify the event type occurring and the object that triggered it. }. QAction* pasteAction.h: 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 #ifndef SOFTKEYS_H #define SOFTKEYS_H #include <QtGui/QMainWindow> #include <QAction> #include "ui_Softkeys.
pasteAction->setEnabled(false). } else if(obj->objectName()=="editPaste") { cutAction->setEnabled(false). QEvent *event) { if (event->type() == QEvent::FocusIn) { //focus in event received if(obj->objectName()=="editCut") { cutAction->setEnabled(true). pasteAction->setEnabled(false). } else { //passing the event to the parent . SLOT(cutEditor())). return true. } bool Softkeys::eventFilter(QObject *obj.editCut->installEventFilter(this). //register event filters for focus event notifications ui. pasteAction->setEnabled(true). //register actions on the menu cutAction=menuBar()->addAction( "Cut". return true. } return true. this. this. //clear clipboard clipboard="".148 Qt for Symbian 32 33 #endif // SOFTKEYS_H Softkeys.setupUi(this).cpp: 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 #include "Softkeys.editPaste->installEventFilter(this). cutAction->setEnabled(false). SLOT(pasteEditor())). pasteAction=menuBar()->addAction( "Paste". ui.h" Softkeys::Softkeys(QWidget *parent) : QMainWindow(parent) { ui.
) are reported via signals. which means that all the important events (successfully downloaded fragment.editCut->setText(""). event). etc. Our application that demonstrates the QNetworkAccessManager functionality will be a simple website downloader. which are offered by the QNetworkReply object. The network class library offers various classes that allow the developer to write low-level networking applications. e. The easiest way to do this is by using the QNetworkAccessManager::get() function. we should use a simple HTTP get request.5 Website Downloader In this section one of the most commonly used classes in the QtNetwork module. ui. It offers a simple and useful interface. Generally. } void Softkeys::pasteEditor() { //paste functionality ui.Qt for Symbian Examples 149 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60 61 return QMainWindow::eventFilter(obj. In the case of implementing a website downloader application. .editPaste->setText(clipboard). } Softkeys::~Softkeys(){} Figure 7.g. and a QLabel widget on which the response will be displayed. which class might be useful in order to obtain all the downloaded data and metadata. Its user interface (see Table 7. error detected in processing. When the get request is finished. QNetworkAccessManager is responsible for posting requests and receiving replies. a QLabel.5 shows what the context-sensitive softkey menu would look like on a Symbian mobile device. so – after an instance of this class has been created – the developer could use its methods to launch requests over the network (represented as QNetworkRequest objects) without a huge effort. The returned object is a QNetworkReply instance. 7. and high-level protocol-specific clients like FTP or HTTP. a progress bar that allows the user to monitor the download process. is introduced. (encrypted) socket servers/clients. The request runs asynchronously. which can be very useful if we want to show a progress bar on our window). } } void Softkeys::cutEditor() { //cut functionality clipboard=ui.2. and downloadProgress() (emitted to indicate the current progress of the download.editCut->text().3) will consist of an input field for providing the URL. a button for starting the request. called QNetworkAccessManager. In the following example. we connect two of these to our QMainWindows slots: finished() (emitted when a request is finished). we can use the QNetworkReply::readAll() method to access the downloaded content and place it on the surface of a widget.
it is important to add the network to the project descriptor (usually called <MainWindowName>. Note that. before compiling and running an application that uses a class from the QtNetwork module. The header file and the implementation of the website downloader application are listed below.5 The softkeys example running on the Symbian emulator.150 Qt for Symbian Figure 7.pro) file: Downloader.h" class Downloader : public QMainWindow { Q_OBJECT .h: 1 2 3 4 5 6 7 8 9 10 11 12 13 #ifndef DOWNLOADER_H #define DOWNLOADER_H #include #include #include #include #include <QtGui/QMainWindow> <QNetworkAccessManager> <QNetworkRequest> <QNetworkReply> "ui_Downloader.
} .3 UI design of the website downloader example. ~Downloader(). void on_receivingProgress(qint64 done. qint64 total).h" #include <QUrl> Downloader::Downloader(QWidget *parent) : QMainWindow(parent) { ui. QNetworkAccessManager netManager.setupUi(this). }. private: Ui::DownloaderClass ui.cpp: 1 2 3 4 5 6 7 8 9 #include "Downloader. #endif // DOWNLOADER_H Downloader. private slots: void on_btnDownload_clicked().Qt for Symbian Examples 151 Table 7. void on_download_finished(). QLineEdit editUrl QPushButton btnDownload QProgressBar prgDownload QLabel lblContent Spacer Input value Starts downloading Progress bar Displays result For layout alignment purposes outcome 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 public: Downloader(QWidget *parent = 0).
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void Downloader::on_btnDownload_clicked() { ui.progressDownload->setValue(0); //sets the requested url QUrl url("http://" + ui.editUrl->text()); QString hostname = url.encodedHost(); QString file = url.encodedPath(); //init request QNetworkRequest request; request.setUrl(url); QNetworkReply *reply = manager->get(request); connect(reply, SIGNAL(finished()), this, SLOT(on_download_finished()) ); connect(reply, SIGNAL(downloadProgress(qint64, qint64)), this, SLOT(on_receivingProgress(qint64, qint64))); } void Downloader::on_download_finished() { QByteArray resp=http->readAll(); ui.lblContent->setText(QString(resp.data())); } void Downloader::on_receivingProgress(qint64 done, qint64 total) { ui.progressDownload->setMaximum(total); ui.progressDownload->setValue(done); } Downloader::~Downloader() { }
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In Figure 7.6 you can see how the HTTP client could be used to download and display simple HTML pages.
7.2.6 Stored Settings
In the following example, the XML processing library of the Qt platform is introduced. Our demo application's source code will explain how the QXmlStreamReader class can be used for parsing an input configuration written in XML. This reader class handles the input XML document as a stream of tokens, just like the standard SAX parser. As you will see, the difference is that, while the SAX parsing is based on asynchronous call-back functions, QXmlStreamReader supports
Qt for Symbian Examples
Figure 7.6 Downloading a simple website using the demo application.
loop-based reading, which can be helpful, for example, in implementing recursive processing by splitting the parsing logic of different types of elements into different methods (demonstrated in the FriendsApp example below). Our very first XML parser function will be responsible for processing the following XML file input: <?xml version="1.0"?> <settings> <label> <red value="255" /> <green value="0" /> <blue value="0" /> </label> <slider value="22" /> <time value="02:02:22" /> </settings> As you may have guessed, this structure describes the predefined set values of a few widget items: the background colour of a QLabel, the value of a QSlider, and the displayed time of a QTimeEdit, respectively. The parsing function parseSettings() will be called immediately after setting up the UI, and then the read values will be applied by calling the applySettings() function. Therefore, if the input document is well formed, after launching the application a set of widgets (presented in Table 7.4) containing the read values will be shown. The header file and the implementation of the stored settings example are listed as follows:
Qt for Symbian
Table 7.4 UI design of the stored settings example.
QLabel lblHeader QSlider horizontalSlider QTimeEdit timeEdit Spacer
Will change its background colour Will change its value Will change its displayed time For layout alignment purposes
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#ifndef STOREDSETTINGS_H #define STOREDSETTINGS_H #include #include #include #include <QtGui/QMainWindow> <QFile> <QXmlStreamReader> "ui_StoredSettings.h"
class StoredSettings : public QMainWindow { Q_OBJECT public: StoredSettings(QWidget *parent = 0); ~StoredSettings(); private: Ui::StoredSettingsClass ui; //variables storing processed input QColor settingsColor; int settingsSlider; QTime settingsTime; void parseSettings(const QString& data); void applySettings(); }; #endif // STOREDSETTINGS_H
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#include "StoredSettings.h" StoredSettings::StoredSettings(QWidget *parent) : QMainWindow(parent) { ui.setupUi(this); // Open input file QFile settingsFile("stored_settings.xml"); if (settingsFile.open(QIODevice::ReadOnly)) { parseSettings(settingsFile.readAll().data()); //parse input file settingsFile.close(); applySettings(); } } void StoredSettings::parseSettings(const QString& data) { QXmlStreamReader reader(data); bool inSettingsTag=false; bool inLabelTag=false; while (!reader.atEnd()) { reader.readNext(); //read next token if (reader.tokenType() == QXmlStreamReader::StartElement) { if (reader.name() == "settings") { inSettingsTag=true; } else if(reader.name() == "label" && inSettingsTag) { inLabelTag=true; } else if(reader.name() == "red" && inLabelTag) { int value= reader.attributes() .value("value").toString().toInt(); settingsColor.setRed(value); } else if(reader.name() == "green" && inLabelTag) { int value= reader.attributes() .value("value").toString().toInt(); settingsColor.setGreen(value); } else if(reader.name() == "blue" && inLabelTag) {
value("value"). }"). ui.toString().2.attributes() . else if(reader.toString().value("value").7 you can see what the Qt form looks like after parsing and processing the input XML file. } else if(reader. settingsTime=QTime::fromString(timeString). } else if(reader. 7. settingsColor.156 Qt for Symbian 47 48 49 50 51 52 53 54 55 56 57 58 59 60 61 62 63 64 65 66 67 68 69 70 71 72 73 74 75 76 77 78 79 80 81 82 83 84 85 86 int value= reader. } StoredSettings::~StoredSettings() {} In Figure 7.name() == "label") inLabelTag=false.lblHeader->setStyleSheet("QLabel { background-color: "+ settingsColor. since it uses most of the previously introduced modules of the Qt framework in order .name() == "slider" && inSettingsTag) { settingsSlider= reader.tokenType() == QXmlStreamReader::EndElement) { if(reader.horizontalSlider->setValue(settingsSlider). ui. } } //while !reader.toInt().value("value").name()+".toInt().toString(). } } //startElement else if (reader.timeEdit->setTime(settingsTime).atEnd() } void StoredSettings::applySettings() { ui.name() == "settings") inSettingsTag=false.attributes() .setBlue(value).name() == "time" && inSettingsTag) { QString timeString= reader.attributes() .7 FriendsApp Our very last example application concerning Qt XML and networking functions might seem a little more complex.
sending text messages. since all the FriendsApp functions provided by the server – fetching or managing friends. First. thus QXmlStreamReader will be used in order the process the pulled data bundle. an error message will be transmitted as a login response. The login query looks as follows (note that in our demonstration the password is transmitted as plain text. The scheme of such a message is as follows: <friendsapp> <message code="error_code"/> <friendsapp> .7 The stored settings example running on the Symbian emulator. we take a closer look at the communication process. advanced authentication methods or ciphering are not included): http://<server_address>/?function=login&email= <user_login_email>&password=<password> The server's response for a login request in which valid credentials are provided is as follows: <friendsapp> <login> <id>user_id</id> <sid>session_id</sid> <email>user_login_email</email> <nick>user_nick</nick> </login> </friendsapp> The most important node of this login response is the session ID (tagged <sid>). If the given username or password is incorrect. FriendsApp was meant to be created only for demonstration purposes. searching. The server's response is always an XML document. The communication process between the server and the mobile client is realized via HTTP get requests completed with the proper query parameters describing the requested operation. etc. which are the login process and the downloading of a user's friend list. – require (sometimes among others) a valid sid as an input parameter. so its functionality will cover just the simplest use cases of such an application. to realize a mobile client application of a basic social networking site.Qt for Symbian Examples 157 Figure 7.
the UI of our client application consists of more Qt windows. the previously mentioned error message will be transmitted. QString password) and fetchFriendList(). Since the FriendsApp Qt example will cover the function of downloading and displaying current friends and friend request. The communication process between the FriendClient and the widget classes can be realized by connecting the client's signals to the corresponding slots of widget objects. After examining the communication process between the server and the client application. The implementation of the class utilizes the singleton design pattern. you will have to create and a run a server that will respond to the requests sent from the mobile client of FriendsApp.). containing the exact cause of the error. handling network requests and processing responses using the previously introduced SAX parser. so we could use the singleton pattern in order to reach exactly the same instance of the FriendClient class from every Qt window. finally we can implement the network client class of our application which will be responsible for managing the active session. etc. we can examine the request format and the response of the friend fetching function. As you will see. called FriendClient. our client application can request any of the server's functions. This class. Note also that implementing and running the application with this address will result in a login error as the site example. Note in the source code of these functions that the network requests use http://www. The scheme of this list is as follows: <friendsapp> [<friend> <userid>friend_user_id</userid> <nick>friend_nick</nick> <email>friend_login_email</email> <lastlogin>time_of_last_login</lastlogin> </friend> *] [<friend_request> <userid> user_id</userid> <nick>nick</nick> <email> login_email</email> <lastlogin>time_of_last_login</lastlogin> </friend_request> *] </friendsapp> In case of any processing error (wrong sid supplied by the client.com does not really exist.example. Some of these signals . This means that in order to test the functionality of an application based on the following demonstration. server application cannot connect to database.158 Qt for Symbian After a successful login procedure. offers two public methods in order to launch the previously described request: login(QString username.com/friendsapp/ as the address of the FriendsApp server. The request's URL is: http://<server_address>/?function=get_friends&sid =<session_id> The response XML document consists of several <friend> nodes (which represent the actual friends of the user) and <friend_request> nodes (which supply information about incoming friend requests).
h: 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 #ifndef FRIENDSCLIENT_H_ #define FRIENDSCLIENT_H_ #include #include #include #include #include #include #include <QObject> <QNetworkAccessManager> <QNetworkReply> <QUrl> <QString> <QXmlStreamReader> <QDateTime> class FriendsClient : public QObject { Q_OBJECT public: virtual ~FriendsClient(). static FriendsClient* instance. • fetchFinished(int numberOfFriendsFetched) – Emitted at the end of parsing.Qt for Symbian Examples 159 relate to the login procedure (loginSuccess() and loginFailed(int errorcode)) and some to the significant events of the friend list downloading process: • fetchStarted() – Emitted at the start of the parsing process. • friendFetched(QString) – Emitted after successfully parsed friend or friend request element. The header file and the implementation of the FriendClient class based on the described behaviour are listed below: FriendClient. //access managers for network requests QNetworkAccessManager loginAccessManager. //starts the login procedure void fetchFriendList(). The string parameter represents the downloaded friend. QNetworkAccessManager downloadAccessManager. //stores sid after a successful login . //starts friend list fetching private: FriendsClient(). • fetchError() – Emitted in case an error has been raised during the downloading or parsing process. //singleton instance void login(QString. QString). static FriendsClient* getInstance().
SIGNAL(finished(QNetworkReply*)). void fetchFinished(int). void parseFetchReply(const QString &). SLOT(on_loginRequestFinished(QNetworkReply*))).cpp: 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 #include "FriendsClient. //signals emitted to notify the friend list UI class void fetchStarted(). void on_fetchRequestFinished(QNetworkReply*). provides the singleton instance if(!instance) instance=new FriendsClient(). . void loginFailed(int). QString elementName. void friendFetched(QString). void fetchError(). QString parseFriend(QXmlStreamReader &reader. private slots: //callback for finished network request void on_loginRequestFinished(QNetworkReply*).h" FriendsClient* FriendsClient::instance=0. #endif /* FRIENDSCLIENT_H_ */ FriendClient. this. SIGNAL(finished(QNetworkReply*)). }. signals: //signals emitted to notify the login UI class void loginSuccess().160 Qt for Symbian 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60 QString sessionId. connect(&downloadAccessManager. FriendsClient::FriendsClient() { //connecting network signals to private slots connect(&loginAccessManager. //XML parser functions void parseLoginReply(const QString &). SLOT(on_fetchRequestFinished(QNetworkReply*))). this. } FriendsClient::~FriendsClient() {} FriendsClient* FriendsClient::getInstance() { //static functions. bool showLastSeen).
data()).example.addEncodedQueryItem("function".Qt for Symbian Examples 161 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60 61 62 63 64 65 66 67 return instance. "login"). } void FriendsClient::on_loginRequestFinished(QNetworkReply* reply) { //reads the login response if (!reply->error()) { QByteArray resp=reply->readAll(). } .addEncodedQueryItem("sid". username.addEncodedQueryItem("password".get(QNetworkRequest(url)). } void FriendsClient::fetchFriendList() { //starts a fetch request with the supplied parameters QUrl url("http://www.get(QNetworkRequest(url)). } else { emit loginFailed(0). password.toUtf8()). url.com/friendsapp/"). sessionId.data()).example. "get_friends"). url. downloadAccessManager.com/friendsapp/").addEncodedQueryItem("function".toUtf8()). parseFetchReply(resp. url. } } void FriendsClient::on_fetchRequestFinished(QNetworkReply* reply) { //reads the login response if (!reply->error()) { QByteArray resp=reply->readAll(). loginAccessManager. } void FriendsClient::login(QString username. } else { emit fetchError(). url. parseLoginReply(resp. QString password) { //starts a login request with the supplied parameters QUrl url("http://www.toUtf8()). url.addEncodedQueryItem("email".
} void FriendsClient::parseFetchReply(const QString &respString) { QXmlStreamReader reader(respString). } else if(reader. emit loginFailed(param.name() == "friend_request") { QString text=parseFriend(reader. } else if (reader.atEnd()) { reader. fetchedItemCount++. return. emit friendFetched(text). emit on_loginSuccess(). int fetchedItemCount=0. QString("friend").value("code").tokenType() == QXmlStreamReader::StartElement) { if (reader.attributes().atEnd() emit loginFailed(1). emit fetchStarted().name() == "message") { //got a message answer //login failed for some reason //(wrong username. while (!reader.readElementText().) QString param=reader. etc.readNext(). if (reader. true).name() == "sid") { //got a valid sessionId sessionId=reader.name() == "friend") { QString text=parseFriend(reader.toInt()). .readNext(). password.atEnd()) { reader.162 Qt for Symbian 68 69 70 71 72 73 74 75 76 77 78 79 80 81 82 83 84 85 86 87 88 89 90 91 92 93 94 95 96 97 98 99 100 101 102 103 104 105 106 107 108 109 110 111 112 113 114 115 } void FriendsClient::parseLoginReply(const QString &respString) { QXmlStreamReader reader(respString).tokenType() == QXmlStreamReader::StartElement) { if (reader. if (reader. QString("friend_request"). return.toString(). while (!reader. } } } //while !reader.
QDateTime lastSeen. } else if(reader.toInt(). after studying the preceding examples of this chapter.tokenType() == QXmlStreamReader::EndElement && reader.toString("hh:mm dd.yy")+")" : nick. } return showLastSeen ? nick+ " (last seen "+lastSeen.tokenType() == QXmlStreamReader::StartElement) { if(reader. } } } emit fetchFinished(fetchedItemCount).readElementText(). lastSeen=QDateTime::fromTime_t(seconds).Qt for Symbian Examples 163 116 117 118 119 120 121 122 123 124 125 126 127 128 false).name() == "lastlogin") { int seconds=reader. The UI design and the implementation of these form widgets called LoginForm (see Table 7. } } reader. The source code does not contain any unfamiliar code snippet. bool showLastSeen) { QString nick(""). the second form should appear on the screen. while(!(reader.readNext(). emit friendFetched(text+" wants to be your friend"). hence we will dispense with a detailed description of the following classes.readNext().6) follow. The first one is to provide a conventional login surface. After a successful login. reader. consisting of widgets such as username and password editor. the next step is to design the two necessary Qt forms.name() == "nick") { nick=reader. fetchedItemCount++.name() == elementName)) { if(reader. After studying the implementation of the FriendsApp .MM.5) and FriendListForm (see Table 7. } 129 130 131 132 133 134 135 136 137 138 139 140 141 142 143 144 145 146 147 148 149 150 151 152 QString FriendsClient::parseFriend(QXmlStreamReader &reader. QString elementName.readElementText(). on which the user can download the friend list and examine the results. } After implementing the background worker class.
h" . while in Figure 7.5 UI design of the FriendsApp login window.9 you can see how the downloaded XML representation of the contact data will be transformed into a friend list on the GUI: LoginForm. QLabel lblLogin QLineEdit editEmail QLineEdit editPassword QPushButton btnLogin Spacer Status report Login username Login password Start login For layout alignment purposes outcome Table 7.8 shows an unsuccessful login attempt on the login form.164 Qt for Symbian Table 7.h: 1 2 3 4 5 6 7 #ifndef LOGINFORM_H #define LOGINFORM_H #include <QtGui/QMainWindow> #include "ui_LoginForm.6 UI design of the FriendsApp friend list window.h" #include "FriendsClient. Figure 7. QLabel lblStatus QPushButton btnRefresh QListView listFriends Spacer Status report Starts fetching Displays fetched items For layout alignment purposes outcome UI classes. you might take a look at the screenshots of the running application.
9 The XML representation of a downloaded friend list and the corresponding screenshot.Qt for Symbian Examples 165 Figure 7. Figure 7. 8 9 10 11 12 13 14 15 16 17 18 19 20 class LoginForm : public QMainWindow { Q_OBJECT public: LoginForm(QWidget *parent = 0).8 Unsuccessful login attempt in the FriendsApp login form. public slots: . private slots: void on_btnLogin_clicked(). ~LoginForm().
#endif // LOGINFORM_H LoginForm. friendsClient=FriendsClient::getInstance().cpp: 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 #include #include #include #include "LoginForm. SIGNAL(on_loginSuccess()). void on_loginFailed(int). } void LoginForm::on_loginFailed(int messageCode) { ui. private: FriendsClient *friendsClient. } LoginForm::~LoginForm () {} void LoginForm::on_btnLogin_clicked() { friendsClient->login(ui.lblLogin->setText("Login failed: " + .166 Qt for Symbian 21 22 23 24 25 26 27 28 29 30 void on_loginSuccess(). Ui::LoginFormClass ui. connect(friendsClient. }.editPassword->text()).setupUi(this). fl->showMaximized(). SLOT(on_loginSuccess())).ui.h" LoginForm::LoginForm(QWidget *parent) : QMainWindow(parent) { ui. connect(friendsClient. this. SLOT(on_loginFailed(int))). SIGNAL(on_loginFailed(int)).editEmail->text().h" <QByteArray> <QString> "FriendListForm. this. } void LoginForm::on_loginSuccess() { FriendListForm* fl=new FriendList().
}. ui. connect(friendsClient. ~FriendListForm().listFriends.setupUi(this). friendsClient=FriendsClient::getInstance(). #endif // FRIENDLISTFORM_H FriendListForm. } FriendListForm.Qt for Symbian Examples 167 37 38 QString::number(messageCode)).cpp: 1 2 3 4 5 6 7 8 9 10 11 #include "FriendListForm. FriendsClient* friendsClient.h: 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 #ifndef FRIENDLISTFORM_H #define FRIENDLISTFORM_H #include #include #include #include <QtGui/QWidget> <QString> "ui_FriendListForm.h" class FriendListForm : public QWidget { Q_OBJECT public: FriendListForm(QWidget *parent = 0). private: Ui::FriendListFormClass ui. void on_fetchFinished(int). void on_friendFetched(QString). private slots: void on_btnRefresh_clicked().h" "FriendsClient. SIGNAL(fetchStarted()). SLOT(clear())).h" FriendListForm::FriendListForm(QWidget *parent) : QWidget(parent) { ui. . public slots: void on_fetchError().
listFriends->addItem(friendStr)."). } void FriendListForm::on_fetchFinished(int itemcount) { ui. SLOT(on_fetchFinished(int))). SLOT(on_friendFetched(QString))).168 Qt for Symbian 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 connect(friendsClient. SLOT(on_fetchError())). } <friendsapp> <friend> <userid>54</userid> <nick>Elemer</nick> <email>me2@abc</email> <lastlogin>1250416017</lastlogin> </friend> <friend> <userid>55</userid> <nick>Joseph</nick> <email>me3@abc</email> . SIGNAL(fetchFinished(int)). } } void FriendListForm::on_friendFetched(QString friendStr) { ui. this.listFriends->addItem("You have no friends. connect(friendsClient. this. connect(friendsClient.lblStatus->setText("Error while fetching"). SIGNAL(fetchError()).lblStatus->setText("Fetched "+QString::number(itemcount)+ " item(s)"). if(!itemcount) { ui. } FriendListForm::~FriendListForm() {} void FriendListForm::on_btnRefresh_clicked() { friendsClient->fetchFriendList(). SIGNAL(friendFetched(QString)). } void FriendListForm::on_fetchError() { ui. this.
The first example program code demonstrates how easy it is to register an orientation change listener with the XQDeviceOrientation class.2). the Sensor API. These technologies include messaging. since. Mobile devices are often crafted with built-in sensor hardware. the downward direction of the screen. we implement a simple application that displays a QWidget. and with the mobile extensions these sensors are also available in Qt. and so on. Symbian OS provides a programming interface that gives developers access to the sensor services. we present the basics of device orientation notifications. After a short introduction. The following short examples will demonstrate the functionality of one of these extension libraries.8 Sensor API In addition to standard Qt class libraries – which were developed originally for use in a desktop environment – mobile extensions for Qt for Symbian offer you a varied set of APIs in order to provide native support for technologies that are available for mobile devices. they can implement the whole application in Qt program code. you have to obtain the Mobile Extensions for Qt for Symbian pack. and install it on your development environment.e. The rotationChanged() signal emitted by the device orientation object will be connected to the update signal to the widget in order to draw an arrow on its surface. The arrow – due to the orientation information – will always point downwards on the Y axis of the device's coordinate system (i. In order to access their services. The second example covers the topic of the acceleration meter API (accessible through the XQAccelerationSensor class). To demonstrate the functionality of the XQDeviceOrientation class. Check the documentation on mobile extensions for more details. an acceleration meter. as you can see in Figure 5.2. a camera. The interfaces allow developers to reach the Symbian mobile technologies without a huge effort. location-based services.Qt for Symbian Examples 169 <lastlogin>1250416040</lastlogin> </friend> <friend> <userid>56</userid> <nick>Cornelius</nick> <email>me4@abc</email> <lastlogin>1250425144</lastlogin> </friend> <friend_request> <userid>57</userid> <nick>Paula</nick> <email>me5@abc</email> <lastlogin>1251483051</lastlogin> </friend_request> </friendsapp> 7. which is trickier to use. The reason for this is because acceleration sensor events are triggered so often that they cannot be handled using the standard signals and slots interface. Note that the extension classes are not part of the Qt for Symbian SDK. since instead of the Qt signals and slots mechanism it uses the filter pattern. with the extension pack. The implementation of this demonstration app is as follows: .
The sensor provides the calculated gravity values measured on the axis of the phone's own .setPen(color). painter. } void OrientationDemo::updateRotation(int rotx. //specify the angle of the change to notify after orientation->setResolution(5). connect(orientation. painter.5. painter. we now look at a demonstration of the second sensor class called XQAccelerationSensor.setupUi(this). int roty.-30. 255. QPainter painter(this). int rotz) { rotation=roty.rotReal).drawLine(0.14 * rotation / 180. update().170 Qt for Symbian 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 #include "OrientationDemo. } OrientationDemo::~OrientationDemo() {} After this short example. int.translate(this->width()/2. 0).rotate(.-30). SLOT(updateRotation(int.h" #include "xqdeviceorientation.-30. which offers an interface to access the device's acceleration sensor data. painter.setBrush(color). QColor color(255. int)).30). SIGNAL(rotationChanged(int.h" OrientationDemo::OrientationDemo(QWidget *parent) : QWidget(parent) { ui. painter. this.this->height()/2). // Create the orientation sensor object XQDeviceOrientation* orientation = new XQDeviceOrientation(this). // Read the current orientation rotation = orientation->xRotation().0. orientation->open(). int))). } void OrientationDemo::paintEvent(QPaintEvent* event) { //converting rotation into qreal value qreal rotReal= 3. int. painter.drawLine(-5.
Note that the device orientation class introduced previously is actually a filter on the acceleration sensor. Naturally. This pattern can be used. programmers can develop an acceleration filter of their own. which calculates the actual rotation from the measured gravity values. to filter rapidly triggered sensor events and pass the received gravity values to the application at a lower rate. XQAccelerationSensor* accSensor= new XQAccelerationSensor(this). This can be accomplished by implementing the filter class based on the XQAbstractAccelerationSensorFilter interface and registering it using the sensor's addFilter() method. The filter method takes all the measured gravity values as integer parameters. just as the following code snippet demonstrates: 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 #include "AccelerationDemo.2). XQAccelerationDataPostFilter* postFilter = new XQAccelerationDataPostFilter(). int & zAcceleration) { //acceleration information received //you could use the received values for your own purposes //in this demo.h" AccelerationDemo::AccelerationDemo(QWidget *parent) : QWidget(parent) { ui. we just simply show the values on a QLabel ui. 22 23 24 25 26 27 28 29 30 . } bool AccelerationDemo::filter(int& xAcceleration. It also has a return value. in order to implement the special program functionality based on the accessed acceleration data. for example. e.setupUi(this).g.lblAccelerationData->setText( "accX: "+QString::number(xAcceleration)+"\n"+ "accY: "+QString::number(yAcceleration)+"\n"+ "accZ: "+QString::number(zAcceleration)). accSensor->addFilter(*this). which can be used by implementing the filter.Qt for Symbian Examples 171 coordinate system (Figure 5. which indicates whether the received sensor data needs to be filtered out or not. The registered filters are stored in a stack and their filter() methods are called one after the other when a sensor event has been triggered. int& yAcceleration. A filter can be any QObject sub-class. Filters can let their parent application know about the filtered data by emitting signals or calling methods directly. As you may recall. a simple form widget. accSensor->addFilter(*postFilter). //init filter stack and start monitoring accSensor->open(). accSensor->startReceiving(). this sensor data can be accessed by registering filters rather than by the Qt signals and slots mechanism.
you should add a postfilter to the stack before your own filter instance in order to facilitate dealing with different types of devices. a button for sending a message and a QLabel item for displaying notifications about the status of the sending process. In the implementation of the click event handler we simply create a message object based on the provided properties. this class allows you to construct your own custom message and send it using the XQMessaging class. which is responsible for converting the raw acceleration values – which could be represented on a different scale by varying the version of the Symbian platform – to a standard range of −100 to +100. and send it using an instance of the XQMessaging class. without knowing anything about any native Symbian API. • Registering a receiver slot in order to receive notification about incoming messages. in addition to the widget. This filter is actually an XQAccelerationDataPostFilter instance. The received data is accessible through an instance of the XQMessage class. and modifying the sensor data so that the orientation of each acceleration axis is the same for all devices. Many of these functions are already available in Qt from the previously introduced Mobile Extensions Library pack. such as telephony.9 Messaging API Using the Qt programming framework in a mobile environment like Symbian requires access to those functionalities concerning wireless communication that any conventional mobile phone provides. We can realize the text message sending functionality by using the previously introduced classes. multimedia messages (MMS) and emails. After this brief summary. a second filter is added to the sensor. contact data manipulation. messaging services. attachments.2. such as the receiver(s). Therefore. message type. message body. we will demonstrate the functionality of one of these interfaces. 7. this class can also be used for connecting message receiver slots to its signals in order to process the contents of incoming messages. The class implementation of the SMS text sending application is as follows: . the Messaging API. etc. Currently three types of messages are supported by the API: short text messages (SMS). and so on. All of these are handled consistently by the wrapper class called XQMessage. The main advantage of this extension set is that developers can easily access the mobile device's services by writing Qt-style code. Therefore. To illustrate how a minimal effort is necessary to take advantage of these mobile services. which provides an interface for querying and/or manipulating the attributes of a message.7) will consist of text editors for providing the message body and the receiver's phone number. Further. The two main use cases regarding messaging are the following: • Sending messages from your application. } AccelerationDemo::~AccelerationDemo() {} Note that. we will create a demo application that will provide a UI for sending short text messages. Its main form (as you can see in Table 7.172 Qt for Symbian 31 32 33 34 35 //passing data through the filter return false.
SLOT(sendingError(XQMessaging::Error))).lblStatus->setText("Status: (not sent yet)"). connect(messaging. receivers. //init XQMessaging messaging = new XQMessaging(this). this.append(ui.editBody->toPlainText(). SIGNAL(error(XQMessaging::Error)). } void MessagingExample::on_btnSend_clicked() { //send button click event handler //creating the message QString body=ui.editReceiver->text()).setupUi(this).h" MessagingExample::MessagingExample(QWidget *parent) : QMainWindow(parent) { ui. body). QStringList receivers.Qt for Symbian Examples 173 Table 7. ui. XQMessage message(receivers.7 UI design of messaging example application. //and sending the new XQMessage instance . QPlainTextEdit editBody QLineEdit editReceiver QPushButton btnSend QLabel lblStatus Message body Message receiver Sending the text Status reporting outcome 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 #include "MessagingExample.
As described above. SLOT(messageReceived(const XQMessage&))).174 Qt for Symbian 31 32 33 34 35 36 37 38 39 40 41 42 43 44 messaging->send(message).lblStatus->setText("Status: (sent)").body(). // connect slot for incoming message notification connect(messaging. reception of the message is provided by the XQMessaging class. After setting up an instance. SIGNAL(error(XQMessaging::Error)). consider the following code snippet. } void MessagingExample::messageReceived(const XQMessage& message) { //processing the incoming message QString body=message. this. } MessagingExample::~MessagingExample() {} To conclude this section on messaging services. which will demonstrate the method of registering a listener for incoming text messages. 17 18 19 20 21 22 23 24 25 26 . SIGNAL(messageReceived(const XQMessage&)).lblStatus->setText( "Status: (error "+QString::number(err)+")"). // start receiving notifications // the supplied parameters are for filtering the incoming messages // and receive only SMS notifications messaging->startReceiving(XQMessaging::MsgTypeSMS). this. connect(messaging. you have to connect the messageReceived(const XQMessage*) signal to your own slot implementation. in which you can process the received text message: 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 MessagingExample::MessagingExample(QWidget *parent) : QMainWindow(parent) { messaging = new XQMessaging(this). ui. } void MessagingExample::sendingError(XQMessaging::Error err) { //called in case an error has been raised during sending ui. SLOT(receivingError(XQMessaging::Error))).
you may use it for your own purposes.8) consists of the camera preview widget mentioned above and a button which could be used for taking a picture based on the current preview frame.Qt for Symbian Examples 175 27 28 29 30 31 32 33 34 35 // . while the second one provides a programming interface for taking photos and getting the resulting JPEG image.lblStatus->setText( "Status: (error "+QString::number(err)+")").. developers can use the extension classes which are available in the Camera API. In order to show the camera preview image on the UI. After obtaining the resulting image as a byte array or a QImage object. you also need to initialize the viewfinder widget and connect the camera's cameraReady() signal to the start() slot of the viewfinder. we will simply store the image in the implementation of the slot that handles the captured picture and request a widget repaint. such functionality cannot be implemented in any of the standard cross-platform Qt modules. To access the device functionality of the camera. called CameraDemo. 7. and mobile application developers might want to use it in their Qt programs.h: 1 2 3 #ifndef CAMERADEMO_H #define CAMERADEMO_H . The example above does not use this method. you have to initialize the camera device and connect its slots and signals to your application. Picture taking is accessible through the corresponding capture() slot of the camera class.10 Camera API Nowadays many mobile devices come with a built-in camera. the processed image can be reached by connecting a slot to the captureCompleted(QByteArray) or captureCompleted(QImage*) signal of the class. The first one is for displaying a camera preview image on the UI. First. Following these steps provides a basic camera application with capabilities for displaying the preview image and receiving the data of the captured photo. The classes are called XQViewFinderWidget and XQCamera. therefore. demonstrates how you can create a simple photo taker application. In order to do this. Its UI (as you can see in Table 7. The free space on the widget's surface will be used for drawing the captured image.2. } void MessagingExample::receivingError(XQMessaging::Error err) { //called in case an error has been raised during receiving ui. The reimplementation of the form's paintEvent() method will be responsible for drawing the last stored image – if there is any – on the surface of the form: CameraDemo. The procedure for obtaining the camera image is as follows. Naturally. which must be called if no further notifications are needed. } Note that the XQMessaging class – in addition to startReceiving() – also has a method called stopReceiving(). notifications will be received until termination of the application. The following Qt program..
//camera device XQCamera* camera.h" class CameraDemo : public QMainWindow { Q_OBJECT public: CameraDemo(QWidget *parent = 0). //hold the captured image QImage* capturedImage.8 UI design of camera example. int IMAGE_VIEW_HEIGHT. .h" "xqcamera. XQViewFinderWidget viewFinder QPushButton btnCapture Place for drawing captured image Displays camera preview picture Triggers picture taking outcome 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 #include #include #include #include #include #include #include <QtGui/QMainWindow> <QPaintEvent> <QPainter> <QColor> <QImage> "ui_CameraDemo. private: //variables for image drawing int IMAGE_VIEW_WIDTH.176 Qt for Symbian Table 7. ~CameraDemo(). Ui::CameraDemoClass ui. QPoint drawTo.
ui. private slots: void imageCaptured(QImage * image). ui. SLOT(start())).480)). camera.Qt for Symbian Examples 177 33 34 35 36 37 38 39 40 41 42 protected: void paintEvent(QPaintEvent * event). SLOT(capture())).96)). #endif // CAMERADEMO_H CameraDemo. SIGNAL(captureCompleted(QImage*)).10.IMAGE_VIEW_HEIGHT).setY(this->height() . this. //connect the button's clicked signal to the capture slot connect(ui. SIGNAL(clicked()). SLOT(imageCaptured(QImage*))).setX(5). //initialize camera device camera=new XQCamera(this). //connect the camera's captureCompleted signal connect(camera. drawTo.viewFinder->setCamera(*camera). }.cpp: 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 #include "CameraDemo. } void CameraDemo::paintEvent(QPaintEvent* event) .viewFinder.h" CameraDemo::CameraDemo(QWidget *parent) : QMainWindow(parent) { ui. //starting preview when camera is ready connect(camera. SIGNAL(cameraReady()). camera->setCaptureSize(QSize(640. IMAGE_VIEW_HEIGHT = IMAGE_VIEW_WIDTH * 3 / 4. drawTo.btnCapture.5 .viewFinder->setViewfinderSize(QSize(128. //initialize the view finder widget ui.setupUi(this). //initialize variables for image drawing IMAGE_VIEW_WIDTH = this->width() .
0 * IMAGE_VIEW_WIDTH / capturedImage->width() . It might also be useful to connect a slot to the signal of the location provider onStatusChanged(XQLocation::DeviceStatus) in order to be informed about the current availability of the provider and change the behaviour of the application if necessary. elevation or speed). With the Location API extension of the Qt Application Framework. accessing position data on mobile devices has become a more important issue. The wrapper class called XQLocation hides the details of the technology actually used and provides the data in a standard format: the location information is represented as coordinate values of the current latitude.0). and finally to listen for location change notifications in a corresponding slot connected to the location class locationChanged() signal. call its open() method to initialize the underlying provider.11 Location API Since mobile services based on location information are becoming more widely used. 1. alternatively you can connect to the slots specialized for emitting the required information. painter.0 * IMAGE_VIEW_HEIGHT / capturedImage->height()).g. } } void CameraDemo::imageCaptured(QImage * image) { //called by camera device. or the network-based location provider. If you are interested only in certain location values (e.2. //we draw it on the surface of the form if(capturedImage) { QPainter painter(this). painter. The standard way to access location information in Qt for Symbian is to instantiate the XQLocation class. altitudeChanged(). . //requesting repaint in order to draw the image } CameraDemo::~CameraDemo() {} 7.translate(drawTo).scale( 1. painter. //storing the captured image update(). developers are able to access the location information provided by various sets of technologies like the built-in or attached GPS receiver. when capture is completed capturedImage=image. longitude and altitude.drawImage(QPoint(0. etc.*capturedImage). such as speedChanged().178 Qt for Symbian 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60 61 62 63 { //main window repaint //if we have a captured image.
lblLocation->setText( "Latitude: "+QString::number(latitude. 4)+"\n"+ "Speed: "+QString::number(speed. //initialize provider XQLocation* location=new XQLocation(this). } void LocationDemo::updateLocation( double latitude. the UI of which consists of a single QLabel called lblLocation. float)). .lblLocation->setText("Error opening location provider. SLOT(updateLocation(double.Qt for Symbian Examples 179 The following code snippet demonstrates the procedure for requesting location information in practice.setupUi(this). double. } //requesting updates when location changes //note that calling startUpdates(int) instead causes //requesting location information periodically location->startUpdates(). As you can see. 4)+"\n"+ "Altitude: "+QString::number(altitude. 4)+"\n"+ "Longitude: "+QString::number(longitude. double. double longitude. we initialize the XQLocation class in the constructor of our form and connect our slot called updateLocation() to the location changed signal. 'f'. Finally."). 4)). return. SIGNAL(locationChanged(double. 'f'. double. float))). 'f'. double. double altitude. 'f'. //opening the provider if (location->open() != XQLocation::NoError) { ui.h" #include "xqlocation.h" LocationDemo::LocationDemo(QWidget *parent) : QMainWindow(parent) { ui. this. float speed) { ui. The demo application is a simple form. in the implementation of the slot we simply refresh the displayed text of the label based on the received parameters after converting the double values to a displayable form with four-digit precision: 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 #include "LocationDemo. //connecting the location changed slot connect(location. which will be used for displaying the coordinate values obtained.
.180 Qt for Symbian 41 42 43 } LocationDemo::~LocationDemo() {} Note that it is also possible to request updated location data only once (as a single request). In this case. you should use a singe call of the requestUpdate() method instead of startUpdates().
108 AOWrapperPrivate. 48–9 exception handling. 106. 37 ConstructL. 100 data types. 43 . 35. 3. 59 Carbide. 54 C. 122–9 Document Object Model (DOM). 78–80 AOWrapper. 108 Apple Store. 15 AJAX. 110–15 cleanup stack. 101.ts files. 4 error codes. 48–9 delivery. 80–2 call-back functions. 44. 47 CExample. 43 descriptors. 1 arrays. 78. 98 BallExample. 9. 7–10 dialogs. 82–4. 100 classes. 101–2 . 31. 36. 117–19. 121 active objects. 96 CActive. 95–8 Debug perspective. 45 a. 108 AOWrapper. 97 byte-order property. 35 Camera API. 105 event listeners. 29 configuring QT support in. 102 email. 106 . 4 C class.h.c++ IDE. 48 communication.sis installation file.pro. 19–20. 96–8 development of Qt. 21 using. 103–5 ActiveState Perl. 103. 104 Calendar API. 111–14 Capabilities. 143–5 Bluetooth. with Qt for Symbian. 108 AOWrapperPrivate. 35 events.cpp. 46–7 displaying recent messages. 24. 110 AOWrapper. 21. 4 Ericsson. 102 executable files.c++. 142–6 buffer descriptors. 71 EPOC16. 21–6 patching. 26.exec(). 109–10 Symbian-specific. 115–16 error handling.INDEX . 98–9 EXE.prj. 120. 96 central widget. 57 Dynamic Link Library (DLL). 22 deep copy. 106 . 57 Alarms API. 132 Carbide. 99–100 clicked() signal. 98. 31 bouncing ball example. 14. 175–8 CameraDemo. 51–63 connect(). 34 AccountsWidget. 175–8 CAOWrapperPrivate. 78. 21.h.cpp. 4 EPOC32. 101. 104 CActiveScheduler. 20 CBase class.
149. 146–9 painting. 57. 42 M classes. 3 Q_OBJECT macro. 87–8 properties. 95–8 networking. 8 Forum Nokia Wiki. 37–8 object ownership. 13. 68 . 138. 43–5 IRDA. 164 Greenphone. 98–9 licensing. 38. 106 Matsushita. 61–2. 130. 14 Keyhole Markup Language. 165. 117–21. 71.pro. 1. 4 memory. 56. 97 'Hello World' application. 107. 4 mobile developers. 6. 17–18 options menu. 29–31 HTTP. 7–9 Mobile Java. 4 object model. 57. 7. 5 MMS. 147 QApplication. 56. 149 Google. 20–1 Installer API. 22–5. 164 LString. 7–8 heap descriptors. 30. 15 perspective. 85–6 layouts. 34 Markfile. 15 MyWorkerClass. 65 Python for S60. 58 Landmarks API. 116 management. 8 SWING module. 157 implicit sharing. 52 installation of Qt for Symbian. 101 exitButton. 26 NTT DOCOMO. 34–5. 6. 40 QAction. 101 pointer descriptors. 59 Novia Ovi Suite. 58. 117 Location API. 7 Java Runtime Environment. 22 platform security. 9. 102 PLUGIN. 3 Java. 1. 77 FriendClient. 75 MagnetoWidget. 158–63 FriendListForm. 163 FriendsApp. 156–69 FTP. 33. 78. 108 MagnetoWidget. 39–40 microkernel architecture.182 Index EXEXP. 32–4 leaves. 167 Python. 2. 3. 34 QBuffer. 107 Profile API. 84–5 internationalization.h. 42 Psion. 21. 65 Motorola. 137–42 naming conventions. 34–5 Open C/C++. 163. 5 public slots:. 8. 172 MOAP(S). 14. 62 graphical user interface (GUI). 49–51 Perl. 5–6 allocation. 1–4 mobile domain. 98–101 Messaging API. 172–5 meta-information. 60. 4. 68 QContactManager. 97 private implementation (pimp) pattern. 146. 42 meta-object compiler (moc). 43 Input/Output. 3. 56–63 NetworkServices. 52–6 Flash. 78. 108 MagnetoWidget. 78. 6 plug-in.cpp. 96 Maemo. 35 files. 58. 4. 10 Loader. 39. 108–10 main(). 52 QContact. 178–80 LoginForm. 52 QByteArray. 101.
122. 70 QGeoPositionInfoSource. 73–5 Version. 119. 108 QThread. 53. 52. 72 Battery status. 44. 106 QtTest. 60 QMainWindow. 119. 74 location. 24 Qt Commercial Version. 22. 41. 29. 72 Network. 70 QHBoxLayout. 52. 7. 120 QString. 106 QtXml. 106 QTranslator. 106 QtXmlPatterns. 55 QSystemDeviceInfo. 40. 60. 48. 71. 48–9 QFile. 118. 106. 53 QDataStream. 10 Qt GNU LGPL v2. 131 QPainter. 142 QTimerEvent. 65–76 audio file.Index 183 QCoreApplication. 49 QNetworkAccessManager. 24. 123 QMessageStore. 33 . 74 bearer management. 51 QProcess. 106 QtWebKit. 40. 22. 73 network session. 42 QMouseEvent. 42. 53. 74 publish and subscribe. 54. 132 Qt GNU GPL v3. 43. 69–71 messaging. 153. 67 QNetworkReply. 7. 30. 72–3 service framework. 106 QtServiceFramework. 74 QSystemInfo. 56 QLabel. 67 Power state. 57. 65–6 contacts. 40 QIODevice. 137. 49. 70 QGeoSatelliteInfoSource. 72 QtCore. 74 Qt C++. 46 QEvent. 153 QStackedLayout. 73 system information. 22. 70 QGeoCoordinate.0. 140 qmake. 45 QT Mobility APIs. 25. 73 SIM. 119. 38. 123 QMetaObject. 106 QTcpServer. 142 QPaintEvent. 44 Qt Designer Editor. 52 QPushButton. 53. 57 QObject. 57 QIntValidator. 24. 49 QtNetwork. 37. 77–93 Qt Linguist. 67. 46 QtScript. 34. 40 QHttp. 179 QLineEdit. 136. 70 QGeoPositionInfo. 74 Storage information. 107. 70 QGeoSatelliteInfo. 56 QDialog. 10 Qt Designer. 56 QtGui. 47. 55 QVBoxLayout. 7 QtSvg. 172. 132 Widget Box. 49. 42. 73 features. 49. 50. 42. 41. 35. 131 QtSoftware. 48 QServicePluginInterface. 24. 43 QMediaPlaylist. 26 Property Editor. 39. 52. 51. 34 QVariant. 119 QTimer. 149 QNetworkConfigurationManager.1. 56 QTextStream. 57 QGeoAreaMonitor. 149. 74 Profile. 68–9 Device information. 52. 45. 72 QMessageServiceAction. 71 multimedia. 57 QFtp. 73 device information. 10 Qt-like API extensions. 149 QNetworkRequest. 73 videos. 129 QSlider. 56 QTcpSocket. 57. 58 quit(). 73 Input method. 53. 74 Display information.
56–63. 45–6 using. 15 UIQ3.184 Index QWidget. 169–72 Series 40 (S40). 63. 44. 4. 98 Trolltech. 4. 15–17 documentation folder. 49. 49–51 TPriority. 57 TDes. 105 S60. 137–42 XML. 95–8 Symbian Platform SDK. 158 XMlDataView. 102 U1D2. 42. 129–32 Service Framework Library. 153. 175 . 129–32 setValue(int). 37. 96 streams. 88–9. 17 installation. 3. 79 XQCalendar. 91–2 validators. 37 shallow copy. 4–6 class naming conventions. 44–5 TRAP harness. 33 SLOT(). 36 'signals and slots'. 48 Windows. 97 TDesC. method 51 static classes. 29 Volvo. 40–1 valueChanged(int). 33 SQL. 152–3. 56 UIQ. 172 Sony Ericsson. 39 Simple API for XML (SAX). 40–1 custom. 142. 33 User Interface (UI). 13. 15 spinBox. 132–7 implementation. 58. 38 implementation. 15. 107. 98 thin templates. 122–8 RIM. 172 XQAccelerationSensor. 59–60 XQAccelerationDataPostFilter. 16 patching 3rd Edition feature Pack 1. 78. 61. 50 RThread. 82–3. 38. 33. 17 Symbian OS. 56. 92–3 Visual Studio. 41 Skype. 4 SIGNAL(). 78. 42 RecentMessagesWidget. 131 service plug-in. 157 R classes. 6 startTimer(). 71. 16 T classes. 36. 52–6 StringLoader. 110. 78. 100 U1D1. 97 Telephony API. 115. 17 epoc32. 117. 101–2 threads. 16 Symbian Developer Library. 169. 13 Windows Mobile. 102 U1D3. 6. 149–52 widgets. 132. 1 SAX parser. 81–2 XQCamera. 7 slider. 46. 1 RotateWidget. 44 Symbian C++. 8 service framework. 39. 42–7 Utils API. 170 XQAlarms. 9. 36 SMS. 95–6 TCP. 37 Vibra API. 157. 57 website downloader. 33 SIBO.0. 156. 48 sub-classing. 75 worker class example. 102 UDP. 90–1 TFixedArray. 43 show(). 8. 35–6 connecting. 4 SAMSUNG. 105 timers. 104 translation of text. 158 Sensor API. 7 Web 2. 169 QXmlStreamReader. 57. 36. 35–7 basic. 34. 96 RBuf descriptor. 57 SimpleMultiplier. 78. 78. 7–8 two-phase construction.
86 XQLocation. 169 XQLandmark. 175 . 90–1 XQUtils. 87–8 XQTelephony. 175 XQProfile. 91–2 XQVibra. 91 XQDeviceOrientation. 88–9. 178. 86 XQLandmarkManager. 92–3 XQViewFinderWidget . 174. 172. 179 XQMessaging.Index 185 XQConversions.