拍摄照片

Question

我在拍摄照片时遇到问题。我已经尝试解决了 3 天，希望您能帮我解决这个问题。

我的xml：

<CaptureElement x:Name="capturePreview" Stretch="Uniform" Grid.Column="0" Height="200" Width="300"
                                VerticalAlignment="Center" HorizontalAlignment="Center"/>

            <Image x:Name="imagePreivew" Stretch="Uniform" Grid.Column="1"
                       VerticalAlignment="Center" HorizontalAlignment="Stretch"/>

            <StackPanel Orientation="Horizontal">
                <Button Click="InitCameraBtn_Click" Content="Initialize Camera" />
                <Button Click="StartPreviewBtn_Click" Content="Start Capture Preview" />
                <Button Click="TakePhotoBtn_Click" Content="Capture Photo"/>
            </StackPanel>

还有我的cs

private Windows.Media.Capture.MediaCapture captureManager;
    public MainPage()
    {
        this.InitializeComponent(); 
    }

    private static async Task<DeviceInformation> GetCameraID(Windows.Devices.Enumeration.Panel desiredCamera)
    {
        // get available devices for capturing pictures
        DeviceInformation deviceID = (await DeviceInformation.FindAllAsync(DeviceClass.VideoCapture))
            .FirstOrDefault(x => x.EnclosureLocation != null && x.EnclosureLocation.Panel == desiredCamera);

        if (deviceID != null) return deviceID;
        else throw new Exception(string.Format("Camera of type {0} doesn't exist.", desiredCamera));
    }

    async private void InitCameraBtn_Click(object sender, RoutedEventArgs e)
    {
        var cameraID = await GetCameraID(Windows.Devices.Enumeration.Panel.Back);
        captureManager = new MediaCapture();

        await captureManager.InitializeAsync(new MediaCaptureInitializationSettings
        {
            StreamingCaptureMode = StreamingCaptureMode.Video,
            PhotoCaptureSource = PhotoCaptureSource.VideoPreview,
            AudioDeviceId = string.Empty,
            VideoDeviceId = cameraID.Id
        });

        var maxResolution = captureManager.VideoDeviceController.GetAvailableMediaStreamProperties(MediaStreamType.Photo).Aggregate((i1, i2) => (i1 as VideoEncodingProperties).Width > (i2 as VideoEncodingProperties).Width ? i1 : i2);
        await captureManager.VideoDeviceController.SetMediaStreamPropertiesAsync(MediaStreamType.Photo, maxResolution);
    }

    async private void StartPreviewBtn_Click(object sender, RoutedEventArgs e)
    {
        // rotate to see preview vertically
        captureManager.SetPreviewRotation(VideoRotation.Clockwise90Degrees);
        capturePreview.Source = captureManager;
        await captureManager.StartPreviewAsync();
    }

    async private void TakePhotoBtn_Click(object sender, RoutedEventArgs e)
    {
        // create a file
        StorageFile photoFile = await ApplicationData.Current.LocalFolder.CreateFileAsync("myFirstPhoto.jpg", CreationCollisionOption.ReplaceExisting);

        // take a photo with choosen Encoding
        await captureManager.CapturePhotoToStorageFileAsync(ImageEncodingProperties.CreateJpeg(), photoFile);

        // we can also take a photo to memory stream
        // InMemoryRandomAccessStream memStream = new InMemoryRandomAccessStream();
        // await captureManager.CapturePhotoToStreamAsync(ImageEncodingProperties.CreateJpegXR(), memStream);

        // show a photo on screen
        BitmapImage bitmapToShow = new BitmapImage(new Uri(photoFile.Path));
        imagePreivew.Source = bitmapToShow;  // show image on screen inside Image control defined in XAML
    } 
public void Dispose()
{
    if (mediaCapture != null)
    {
        mediaCapture.Dispose();
        mediaCapture = null;
    }
}

我做错了什么？如果我点击 initliaze 什么都不会做，当我点击其他按钮时，我什至看不到相机，我会收到这样的异常：+

$exception  {System.Exception: The GPU device instance has been suspended. Use GetDeviceRemovedReason to determine the appropriate action. (Exception from HRESULT: 0x887A0005)
   at System.Runtime.CompilerServices.TaskAwaiter.ThrowForNonSuccess(Task task)
   at System.Runtime.CompilerServices.TaskAwaiter.HandleNonSuccessAndDebuggerNotification(Task task)
   at System.Runtime.CompilerServices.TaskAwaiter.GetResult()
   at Save_bills.MainPage.<TakePhotoBtn_Click>d__13.MoveNext()
--- End of stack trace from previous location where exception was thrown ---
   at System.Runtime.CompilerServices.AsyncMethodBuilderCore.<ThrowAsync>b__3(Object state)
   at System.Threading.WinRTSynchronizationContext.Invoker.InvokeCore()}    System.Exception

和

 +      $exception  {System.Exception: The text associated with this error code could not be found.

The text associated with this error code could not be found.

   at System.Runtime.CompilerServices.TaskAwaiter.ThrowForNonSuccess(Task task)
   at System.Runtime.CompilerServices.TaskAwaiter.HandleNonSuccessAndDebuggerNotification(Task task)
   at System.Runtime.CompilerServices.TaskAwaiter.GetResult()
   at Save_bills.MainPage.<InitCameraBtn_Click>d__a.MoveNext()
--- End of stack trace from previous location where exception was thrown ---
   at System.Runtime.CompilerServices.AsyncMethodBuilderCore.<ThrowAsync>b__3(Object state)
   at System.Threading.WinRTSynchronizationContext.Invoker.InvokeCore()}    System.Exception

Answer 1

您正面临这个问题，因为您没有处理您的 MediaCapture 对象，这在处理相机时非常重要。我怀疑在你调试你的应用程序并在没有处理的情况下退出它之后，你在手机上运行普通的相机应用程序会有问题。

您应该做的是在不需要时停止相机预览并处置捕获元素。什么时候做？这取决于几件事：

• 想想Suspending event of your app，只记得在调试时不调用此事件，
• 您也可以使用 Window 的 事件，例如 WindowActivated / VisibilityChanged

出于测试的目的，做这样的事情-在拍照的方法中，最后调用停止预览的方法并调用MediaCapture.Dispose。当你这样做时，调试应用程序，拍照，停止调试。如果你这样做，你应该可以在下次启动应用程序时毫无问题地初始化相机。