camera.py 文件源码

def add_overlay(self, source, size=None, **options):
        """
        Adds an overlay
        :param source: the source
        :param options: See :meth:`~picamera.camera.PiCamera.add_overlay`
        :param size: See :meth:`~picamera.camera.PiCamera.add_overlay`
        """

        overlay = self.camera.add_overlay(source, size=size, **options)

        wait = 0
        while True:
            if overlay.window[2] > 0:
                break
            wait += 1
            if wait > 10:
                raise RuntimeError('Waited longer than 10 seconds for overlay window')
            sleep(1)

        return overlay