拍摄照片 [英] Capture a photo

问题描述

我在拍摄照片时遇到问题.我已经尝试解决这个问题 3 天了，希望你能帮我解决这个问题.

I have problem with capturing a photo. I have tried to solve this for 3 days, I hope that you will help me with this.

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 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 什么也不会做，当我点击其他按钮时，我什至看不到相机，我会得到这样的异常:+

What am I doing wrong? If I click initliaze nothing is going to do I cant even see camera when I click other buttons I get an exception like this: +

$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

推荐答案

你正面临这个问题，因为你没有处理你的 MediaCapture 对象，什么是非常重要的处理相机.我怀疑在您调试您的应用程序并在没有处理的情况下退出它后，您将无法在手机上运行正常的相机应用程序.

You are facing this issue beacause you are not Disposing your MediaCapture object, what is very important when dealing with camera. I suspect that after you debug your app and exit it without disposing, you will have problem to run the normal camera app on the phone.

您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?这取决于以下几点:

What you should do is to stop camera preview when it's not needed and dispose the capture element. When to do it? It depends on few things:

• 想想暂停应用程序的事件，请记住，在调试时不会调用此事件，
• 您还可以使用 Window 的 事件，例如 WindowActivated/VisibilityChanged

• think of Suspending event of your app, remember only that this event is not called when you are debugging,
• you may also use Window's events like WindowActivated / VisibilityChanged

为了测试的目的，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.如果您这样做，下次启动应用程序时，您应该能够毫无问题地初始化相机.

For the purpose of a test, do such a thing - in the method taking photo, at the end, call method stopping preview and call MediaCapture.Dispose. When you do this, debug the app, take a photo, stop debugging. If you do this, you should be able to initialize the camera without problems next time you start the app.

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