参考：https://www.coder.work/article/2085334

内容：在winform和opencvsharp的环境下，利用一个button事件控制相机（打开和关闭），并将相机获取的图片显示在picturebox中。

    VideoCapture capture;
    Mat frame;
    Bitmap image;
    private Thread camera;
    int isCameraRunning = 0;

private void 打开相机_Click(object sender, EventArgs e)
        {
            try
            {
                if (打开相机.Text.Equals("打开相机"))
                {
                    CaptureCamera();
                    打开相机.Text = "关闭相机";
                    isCameraRunning = 1;
                }
                else
                {
                    capture.Release();
                    打开相机.Text = "打开相机";
                    isCameraRunning = 0;
                }
            }
            catch (NullReferenceException exception)
            {
                MessageBox.Show(exception.Message);
            }
        }

private void CaptureCamera()
        {
            camera = new Thread(new ThreadStart(CaptureCameraCallback));
            camera.Start();
        }

private void CaptureCameraCallback()
        {
            frame = new Mat();
            capture = new VideoCapture();
            capture.Open(0);
            while (isCameraRunning == 1)
            {
                bool read_success = capture.Read(frame);
                if (!read_success)
                {
                    MessageBox.Show("无法读取摄像头的帧！！！", "提示：");
                }
                else
                {    //防止状态切换太快，读到空值
                    if (frame.Height == 0) continue;
                    image = BitmapConverter.ToBitmap(frame);
                    pictureBox1.Image = image;
                    image = null;
                }
                //Cv2.WaitKey(20);
            }

        }