title: Problem: The size or resolution of the kivy camera is small
body: <p>Why is the screen size of the camera on the screen so small?While I adjusted the full screen size.When I change the resolution, the application does not come up on the phone . With opencv resolution 640, 480 full screen is displayed
  Sorry my English is not good</p>
  <pre><code>from kivy.app import App
  from kivy.lang import Builder
  from kivy.uix.boxlayout import BoxLayout
  # import time
  Builder.load_string('''
  &lt;CameraClick&gt;:
      BoxLayout: 
          id:boxz  
          orientation: 'vertical'
          Camera:
              id: camera
              size_hint: None , None
              size: boxz.width , boxz.height
              pos_hint :{&quot;center_x&quot;:.5}
              resolution: (640, 480)
              play: False
          ToggleButton:
              text: 'Play'
              on_press: camera.play = not camera.play
              size_hint_y: None
              height: '48dp'
          Button:
              text: 'Capture'
              size_hint_y: None
              height: '48dp'
              on_press: root.capture()
  ''')
  
  
  class CameraClick(BoxLayout):
      def capture(self):
          '''
          Function to capture the images and give them the names
          according to their captured time and date.
          '''
          camera = self.ids['camera']
          # timestr = time.strftime(&quot;%Y%m%d_%H%M%S&quot;)
          camera.export_to_png(&quot;11.png&quot;)
          print(&quot;Captured&quot;)
  
  
  class TestCamera(App):
  
      def build(self):
          return CameraClick()
  
  
  TestCamera().run()
  </code></pre>
  <p><a href="https://i.stack.imgur.com/SYfvG.png" rel="nofollow noreferrer">enter image description here</a>
  <a href="https://i.stack.imgur.com/bI6cf.png" rel="nofollow noreferrer">enter image description here</a></p>