WindowsPhone 8.1 FlashLight

Question

我有诺基亚730，我想让FlashLight在上面工作。但是下一次代码崩溃：

     MediaCapture mc = new MediaCapture();
        await mc.InitializeAsync();

            if (mc.VideoDeviceController.TorchControl.Supported == true)
            {
                mc.VideoDeviceController.TorchControl.Enabled = true;
                mc.VideoDeviceController.TorchControl.PowerPercent = 100; // here is crash
            }

有什么想法吗？由于某些原因，使用较旧平台(wp7、wp8)的解决方案根本不起作用。

Answer 1

通过下一段代码修复：

        private async void Button_Click(object sender, RoutedEventArgs e)
    {
        // Initialize Media Capture and Settings Objects, mediaCapture declared global outside this method 
        var mediaCapture = new MediaCapture();

        // Grab all available VideoCapture Devices and find rear device (usually has flash)
        await mediaCapture.InitializeAsync();

        var videoEncodingProperties = MediaEncodingProfile.CreateMp4(VideoEncodingQuality.Vga);

        var videoStorageFile = await KnownFolders.VideosLibrary.CreateFileAsync("tempVideo.mp4", CreationCollisionOption.GenerateUniqueName);
        await mediaCapture.StartRecordToStorageFileAsync(videoEncodingProperties, videoStorageFile);

        await Task.Delay(TimeSpan.FromMilliseconds(500));
        mediaCapture.VideoDeviceController.TorchControl.Enabled = true;
    }

但是由于某些原因，我应该在启用TorchControl之前等待500毫秒。有人能解释一下原因吗？

Answer 2

根据this post的说法，尝试以下方法可能会有所帮助：

//to switch OFF flash light
mc.VideoDeviceController.FlashControl.Enabled = false;
//to switch ON flash light
mc.VideoDeviceController.FlashControl.Enabled = true;