title: show opencv in kivymd screen
body: <p>I am working on drowsiness detection so I need to use OpenCV but i am having a problem showing the webcam stream on kivymd GUI, and I am using multiple screens and I need it to show in a certain one.
  here the code I am using currently</p>
  <pre><code>class KivyCamera(Image):
      def __init__(self, capture, fps, **kwargs):
          super(KivyCamera, self).__init__(**kwargs)
          self.capture = capture
          Clock.schedule_interval(self.update, 1.0 / fps)
  
      def update(self, dt):
          ret, frame = self.capture.read()
          if ret:
              # convert it to texture
              buf1 = cv2.flip(frame, 0)
              buf = buf1.tostring()
              image_texture = Texture.create(
                  size=(frame.shape[1], frame.shape[0]), colorfmt='bgr')
              image_texture.blit_buffer(buf, colorfmt='bgr', bufferfmt='ubyte')
              # display image from the texture
              self.texture = image_texture
  
  
  class CamApp(App):
      def build(self):
          self.capture = cv2.VideoCapture(0)
          self.my_camera = KivyCamera(capture=self.capture, fps=30)
          return self.my_camera
  
      def on_stop(self):
          #without this, app will not exit even if the window is closed
          self.capture.release()
  
  
  if __name__ == '__main__':
      CamApp().run()
  </code></pre>