打开/关闭闪光灯

Question

OK, My issue is quite simple.

I've managed to turn the flash On (and keep it On).

However, I'm still not sure how to turn it off (lol).

Here's my code :

var sensorLocation = CameraSensorLocation.Back;

try
{
    // get the AudioViceoCaptureDevice
    var avDevice = await AudioVideoCaptureDevice.OpenAsync(sensorLocation,
        AudioVideoCaptureDevice.GetAvailableCaptureResolutions(sensorLocation).First());

    // turn flashlight on
    var supportedCameraModes = AudioVideoCaptureDevice
        .GetSupportedPropertyValues(sensorLocation, KnownCameraAudioVideoProperties.VideoTorchMode);
    if (supportedCameraModes.ToList().Contains((UInt32)VideoTorchMode.On))
    {
        avDevice.SetProperty(KnownCameraAudioVideoProperties.VideoTorchMode, VideoTorchMode.On);

        // set flash power to maxinum
        avDevice.SetProperty(KnownCameraAudioVideoProperties.VideoTorchPower,
            AudioVideoCaptureDevice.GetSupportedPropertyRange(sensorLocation, KnownCameraAudioVideoProperties.VideoTorchPower).Max);
    }
    else
    {
        turnWhiteScreen(true);
    }

}
catch (Exception ex)
{
    // Flashlight isn't supported on this device, instead show a White Screen as the flash light
    turnWhiteScreen(true);
}

Any ideas?

---

PS

• I imagined that converting .on s to .off s could have worked, but it doesn't.
• This has been tested on a HTC 8S and Lumia 820.

Answer 1

It looks like you can't retrieve the acquisition device twice (I'm not sure why), so you should store it in a property:

protected AudioVideoCaptureDevice Device { get; set; }

private async void ButtonTurnOn_Click(object sender, RoutedEventArgs e)
{
    var sensorLocation = CameraSensorLocation.Back;

    try
    {
        if (this.Device == null)
        {
            // get the AudioViceoCaptureDevice
            this.Device = await AudioVideoCaptureDevice.OpenAsync(sensorLocation,
            AudioVideoCaptureDevice.GetAvailableCaptureResolutions(sensorLocation).First());
        }

        // turn flashlight on
        var supportedCameraModes = AudioVideoCaptureDevice
            .GetSupportedPropertyValues(sensorLocation, KnownCameraAudioVideoProperties.VideoTorchMode);
        if (supportedCameraModes.ToList().Contains((UInt32)VideoTorchMode.On))
        {
            this.Device.SetProperty(KnownCameraAudioVideoProperties.VideoTorchMode, VideoTorchMode.On);

            // set flash power to maxinum
            this.Device.SetProperty(KnownCameraAudioVideoProperties.VideoTorchPower,
                AudioVideoCaptureDevice.GetSupportedPropertyRange(sensorLocation, KnownCameraAudioVideoProperties.VideoTorchPower).Max);
        }
        else
        {
            turnWhiteScreen(true);
        }

    }
    catch (Exception ex)
    {
        // Flashlight isn't supported on this device, instead show a White Screen as the flash light
        turnWhiteScreen(true);
    }
}

Then, to turn it off:

private void ButtonTurnOff_Click(object sender, RoutedEventArgs e)
{
    var sensorLocation = CameraSensorLocation.Back;

    try
    {
        // turn flashlight on
        var supportedCameraModes = AudioVideoCaptureDevice
            .GetSupportedPropertyValues(sensorLocation, KnownCameraAudioVideoProperties.VideoTorchMode);
        if (this.Device != null && supportedCameraModes.ToList().Contains((UInt32)VideoTorchMode.Off))
        {
            this.Device.SetProperty(KnownCameraAudioVideoProperties.VideoTorchMode, VideoTorchMode.Off);
        }
        else
        {
            turnWhiteScreen(false);
        }
    }
    catch (Exception ex)
    {
        // Flashlight isn't supported on this device, instead show a White Screen as the flash light
        turnWhiteScreen(false);
    }
}

Answer 2

Try this one

private static VideoTorchMode _videoTorchMode = VideoTorchMode.Off;
private AudioVideoCaptureDevice _videoRecordingDevice;

Check torch is exist in device.

private async void CheckTorch() {
  if(AudioVideoCaptureDevice.AvailableSensorLocations.Contains(CameraSensorLocation.Back) &&
      AudioVideoCaptureDevice.GetSupportedPropertyValues(CameraSensorLocation.Back, KnownCameraAudioVideoProperties.VideoTorchMode).ToList().Contains((UInt32)VideoTorchMode.On)) {
     var temp = AudioVideoCaptureDevice.GetAvailableCaptureResolutions(CameraSensorLocation.Back)[0];
     var resolution = new Windows.Foundation.Size(temp .Width, temp .Height);
     _videoRecordingDevice = await AudioVideoCaptureDevice.OpenAsync(CameraSensorLocation.Back, resolution);
   } 
   else
     MessageBox.Show("Your device does not support torch");
}

To change torch state

private void SetTorchMode(){   
   try {
     if (BackgroundHandler.Instance.IsBackTorchExist) {
        if (_videoTorchMode == VideoTorchMode.Off) {
           _videoRecordingDevice.SetProperty(KnownCameraAudioVideoProperties.VideoTorchMode, VideoTorchMode.On);
           _videoTorchMode = VideoTorchMode.On;
         }
         else {
            _videoRecordingDevice.SetProperty(KnownCameraAudioVideoProperties.VideoTorchMode, VideoTorchMode.Off);
            _videoTorchMode = VideoTorchMode.Off;                                    
         }
      }
   }
   catch (Exception ex){ }
}