拍摄照片

Question

我在拍摄照片时遇到问题。我已经尝试了3天来解决这个问题，希望你能帮助我。

我的 xaml :

<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>

和我的客服

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得到这样的异常：+

$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

你遇到这个问题是因为你没有Disposing你的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，你将无法在 phone.

上运行普通相机应用程序

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

想起Suspending event of your app，只记得这个事件不是调试时调用的，
您还可以使用 Window 的 事件，例如 WindowActivated / 可见性已更改

出于测试的目的，做这样的事情——在拍照的方法中，最后，调用方法停止预览并调用MediaCapture.Dispose。执行此操作时，调试应用程序，拍照，停止调试。如果这样做，下次启动应用程序时应该能够毫无问题地初始化相机。

拍摄照片

Capture a photo

c#

xaml

windows-phone-8.1