

[css3-background] comments

From: Anne van Kesteren <fora@annevankesteren.nl>
Date: Sat, 09 Apr 2005 14:08:09 +0200
Message-ID: <4257C5A9.5060005@annevankesteren.nl>

I think the specification should have a section that clarifies the terms
SHOULD, MUST, etc. The rest of the comments I gave per section. I might 
have missed a few bits, I'll reread the draft when it becomes last call.

* 1. Dependencies with other CSS 3 Modules

Does it really depend on those modules? I think this section need to be
revised. Probably on all CSS3 modules as the graph that was produced a
few weeks ago doesn't seem to be correct. A specification that
implements the CSS3 Background module does not need the 'rgba' color
value for example. It would be nice, but it doesn't depend on it.

* 2.1. Changes from CSS 2.1

There are new 'border' properties as well. 'box-shadow' wasn't in CSS
2.1 either.

* 5. The 'background-image' property

# An image that is empty (zero width or zero height), that fails to
# download, or that otherwise cannot be displayed (e.g., because it is
# not in a supported image format) has the same effect as a non-empty
# transparent image.

Wouldn't it be easier to specify that if an image can't be displayed the
initial value should be used instead?

# If 'background-repeat' or 'background-position' has more
# comma-separated values than 'background-image', the series of values
# is repeated as needed.

As the editor's note already mentioned, it makes more sense for
'background-image' to determine the number of layer and let all the
extra values specified be ignored.

'background-image' that would be 'none' if either 'background-repeat' or
'background-position' has more comma-separated values.

# Editor's Note: Conformance properties for an image should be
# addressed here: MIME type image/*, require support for PNG, refer to
# profiles…


* 6. The 'background-repeat' property

# Should there also be values of "repeat-up", "repeat-down",
# "repeat-right", and "repeat-left" for this property?

What exactly would these values do?

of a large discussion how 'letter-spacing' should be implemented exactly
and it would  be nice if this module would specify in more detail how it
should work. (Personally I think the space at the edge should be halve
the space that is between the images.)

* 8. The 'background-position' property

It would be nice to have a way to position a background from somewhere
else than '0 0' (top left). Using the 'calc()' proposal to express what
I mean:


... it would be very nice if that was made possible. Perhaps using '-5px
-5px' or so.

Or, to determinate the canvas in which the 'background-image' is drawn. 
Such a possibility would also remove the need for the editor's note in 
section 9 and probably remove the need for section 10.

* 11. The 'background-size' property

I'm not sure if this is useful at all. I don't see that a stretched -- 
it is a better name, indeed -- image could work out nice and I expect 
authors to not take advantages of the possiblities. This also introduces 
complexity for UAs and all kinds of rounding issues/errors. I suggest 
marking this as a feature at risk if it is desired by the WG to keep it.

* 16. The 'border-style' properties

I think this should specify that UAs are allowed to fallback to 'solid' 
if they don't have an appropriate implementation for the specified 
values. I think this might be useful for UAs implementating 'border-radius'.

* 18. The 'border-image' property

Again, this makes me wonder how UAs are going to do this "correctly". 
The idea is quite nice, although it seems strange that a 'border' 
property sets the background image...

* 23. The background of the canvas

I think the specification should not give any recommendations anymore to 
authors. Most UAs have implemented support for 'background' on the root 
element. (Even Internet Explorer, be it just for 'background-color'.) I 
also think it should say XHTML/XML or just XML.

* 26. Tests

How can a basic test suite guarentee interoparable implementations? Test 
suites have to be detailed. I'd argue tests are more important than the 

  Anne van Kesteren
Received on Saturday, 9 April 2005 12:07:55 GMT
