python - 实例化后对象仍然没有？

Question

我正在使用树莓派和相机将提要流式传输到网络浏览器。我的 Camera 类尝试两次实例化我的 CameraThread 类（如果 None 则尝试）并停止（因为 picamera 试图被两个不同的对象使用），但理论上这不应该发生。

我试图在 Camera 类的 if 语句中更新一个临时变量，只是为了查看，但该变量没有更新……我不确定这里的问题是什么。

这是我正在使用的代码：

class CameraThread(threading.Thread):
    current_image = None

    def __init__(self):
        super().__init__()
        self.event = threading.Event()
        self.have_image_event = threading.Event()
        self.start()

    def stop(self):
        self.event.set()
        self.join()

    def run(self):
        try:
            with picamera.PiCamera() as camera:
                camera.resolution = (1296, 730)
                capture_image = io.BytesIO()
                temp1, temp2 = io.BytesIO(), io.BytesIO(),
                default_time = 0.033

                for _ in camera.capture_continuous(capture_image, format='jpeg'):
                    # Truncate the stream to the current position (in case
                    # prior iterations output a longer image)
                    capture_image.truncate()
                    capture_image.seek(0)

                    temp1.seek(0)
                    temp1.write(capture_image.read())
                    capture_image.seek(0)
                    temp1.truncate()
                    temp1.seek(0)

                    self.current_image = temp1
                    self.have_image_event.set()

                    temp1, temp2 = temp2, temp1

                    if self.event.wait(default_time):
                        break
        except Exception as ex:
            import traceback
            traceback.print_exc()

class Camera(tornado.web.RequestHandler):
    camera = None

    def get(self):
        if self.camera is None:
            print(self.camera)
            self.camera = CameraThread()
            self.camera.have_image_event.wait()
        self.set_header('Content-type', 'image/jpeg')
        self.set_header('Content-length',
                        self.camera.current_image.getbuffer().nbytes)
        self.set_header('Cache-Control', 'no-cache')
        self.write(self.camera.current_image.read())
        self.finish()

标签： pythonmultithreadingtornadopicamera