Windows phone 7 如何在Windows Phone 7中使用反射停止led手电筒/手电筒应用程序

我正在制作一个手电筒应用程序，在这个应用程序中，我需要不断地使用相机的LED来打开和关闭同一个按钮。我看了这篇文章。开/关操作只能正常工作一次。守则如下：

 private VideoCamera _videoCamera;
 private VideoCameraVisualizer _videoCameraVisualizer;
 bool _isFlashOff = true;

 private void FlashButton_Click(object sender, RoutedEventArgs e)
    {
        try
        {
            if (_isFlashOff)
            {
                _isFlashOff = false;

                // Check to see if the camera is available on the device.
                if (PhotoCamera.IsCameraTypeSupported(CameraType.Primary))
                {
                   // Use standard camera on back of device.
                    _videoCamera = new VideoCamera();
                   // Event is fired when the video camera object has been initialized.
                    _videoCamera.Initialized += VideoCamera_Initialized;

                    // Add the photo camera to the video source
                    _videoCameraVisualizer = new VideoCameraVisualizer();
                    _videoCameraVisualizer.SetSource(_videoCamera);
                }
            }
            else
            {                    
                _isFlashOff = true;
                _videoCamera.StopRecording();
            }
        }
        catch (Exception ex)
        {
            MessageBox.Show(ex.Message);
        }
    }

    private void VideoCamera_Initialized(object sender, EventArgs e)
    {
        _videoCamera.LampEnabled = true;
        _videoCamera.StartRecording();
    }

因为在VideoCamera类中没有实现文章中指定的停止录制方法。我的职能是：

 public void StopRecording()
    {
        // Invoke the stop recording method on the video camera object.
         _videoCameraStopRecordingMethod.Invoke(_videoCamera, null);
    }

问题是当我再次按下按钮时，“Exception”被抛出为“TargetInvocationException”。我无法找出导致异常的问题。StopRecording（）函数正确吗？。\n请尝试以下操作：

---

这是因为您应该只初始化相机一次。请在

on导航到

事件期间执行此操作，然后重新使用相同的实例：

    protected override void OnNavigatedTo(System.Windows.Navigation.NavigationEventArgs e)
    {                    
        // Use standard camera on back of device.
        _videoCamera = new VideoCamera();

        // Event is fired when the video camera object has been initialized.
        _videoCamera.Initialized += VideoCamera_Initialized;


        // Add the photo camera to the video source
        _videoCameraVisualizer = new VideoCameraVisualizer();
        _videoCameraVisualizer.SetSource(_videoCamera);
    }

    private void VideoCamera_Initialized(object sender, EventArgs e)
    {
        isInitialized = true;
    }

    bool isInitialized;
    bool isFlashEnabled;

    private void Button_Click(object sender, System.Windows.RoutedEventArgs e)
    {
        if (!isInitialized)
        {
            MessageBox.Show("Please wait during camera initialization");
            return;
        }

        if (!isFlashEnabled)
        {
            isFlashEnabled = true;

            // Check to see if the camera is available on the device.
            if (PhotoCamera.IsCameraTypeSupported(CameraType.Primary))
            {
                _videoCamera.LampEnabled = true;
                _videoCamera.StartRecording();
            }
        }
        else
        {
            isFlashEnabled = false;

            _videoCamera.StopRecording();
        }
    }

---

您如何实例化

\u videoCameraStopRecordingMethod

？我已将其声明为：private MethodInfo\u videoCameraStopRecordingMethod并实例化为\u videoCameraStopRecordingMethod=videoCameraType.GetMethod（“StopRecording”）；公共void StopRecording（）是否有任何问题方法…？有人能帮我吗…？我需要如何创建StopRecording（）方法…？Awesum回复…非常感谢！！！！KooKiz…你救了我一天…真的非常感谢你的回复…再问一个问题，我怎样才能实现这个手电筒的闪烁功能…@Shaan_14我想，当手电筒滴答作响时，打开或关闭手电筒。当我按下后退按钮移动时，代码出现问题到主页并再次导航到Flashlight页面，我在OnNavigatedTo（System.Windows.Navigation.NavigationEventArgs e）方法的第_videoCameraVisualizer.SetSource（_videoCamera）；行中得到“TargetInvestoryException”异常。而如果我按下Windows按钮或搜索按钮，它就会开始工作。。