renderers.py 文件源码

def update(self, source):
        """
        Update the overlay with a new source of data.

        The new *source* buffer must have the same size as the original buffer
        used to create the overlay. There is currently no method for changing
        the size of an existing overlay (remove and recreate the overlay if you
        require this).
        """
        port = self.renderer[0].input[0]
        fmt = port[0].format
        bp = ct.c_uint8 * (fmt[0].es[0].video.width * fmt[0].es[0].video.height * 3)
        try:
            sp = bp.from_buffer(source)
        except TypeError:
            sp = bp.from_buffer_copy(source)
        buf = mmal.mmal_queue_get(self.pool[0].queue)
        if not buf:
            raise PiCameraRuntimeError(
                "Couldn't get a buffer from the overlay's pool")
        ct.memmove(buf[0].data, sp, buf[0].alloc_size)
        buf[0].length = buf[0].alloc_size
        mmal_check(
            mmal.mmal_port_send_buffer(port, buf),
            prefix="Unable to send a buffer to the overlay's port")