QR-Code in Universal Windows

Question

Wie funktioniert die Vorschau des Videos und die Erkennung von QR (Codes mit ZXing)?

In Windows Phone 8.1 starte ich Vorschau mit MediaCapture und mit VideoEffect QR-Code erkennen.

In Universal Windows VideoEffect funktioniert nicht.

Recognize by timer with CapturePhotoToStorageFileAsync ist langsam.

Answer 1

Also, meine Lösung

1. neue WinRT Projekt erstellen "Windows Runtime-Komponente (Universal Windows-)

2. In WinRT

   erstellen

class CaptureVideoEffect : IBasicVideoEffect (from Windows.Media.Effects) 

3. Effekt an MediaCapture anhängen

await capture.AddEffectAsync(MediaStreamType.VideoPreview, typeof(CaptureVideoEffect).FullName, ...); 

4. Jetzt in CaptureVideoEffect.ProcessFrame (ProcessVideoFrameContext Kontext) Sie Realtime-Video-Ausgang

5. In CaptureVideoEffect bekommen.ProcessFrame überspringen Rahmen, wenn die vorherigen nicht

6. Get Bild als byte []

var frameSize = inputFrameBitmap.PixelWidth * inputFrameBitmap.PixelHeight * 4; 
var frameBuffer = new Windows.Storage.Streams.Buffer((uint)frameSize); 
inputFrameBitmap.CopyToBuffer(frameBuffer); 
byte[] bitmap = frameBuffer.ToArray(); 

7. Decode mit

result = barcodeReader.Decode(bitmap, inputFrameBitmap.PixelWidth, inputFrameBitmap.PixelHeight, BitmapFormat.RGB32); 

public sealed class BarcodeReader 
{ 
    public Result Decode([ReadOnlyArray] byte[] rawRGB, int width, int height, BitmapFormat format); 
} 

Answer 2

Ich denke, Sie haben Recht mit MediaCapture und ZXing Lib, aber ich denke, es sollte Kamera Vorschau Frame funktioniert. Meine Idee ist, die Kamera zu initialisieren, dann den Vorschau-Rahmen zu bekommen und ihn auf WriteableBitmap zu drehen und zuletzt Zxing Api zu verwenden, um dies WriteableBitmap zu analysieren.

<Grid Background="{ThemeResource ApplicationPageBackgroundThemeBrush}"> 
    <Grid.RowDefinitions> 
     <RowDefinition Height="4*" /> 
     <RowDefinition Height="*" /> 
     <RowDefinition Height="*" /> 
     <RowDefinition Height="*" /> 
    </Grid.RowDefinitions> 
    <CaptureElement x:Name="PreviewControl" Stretch="Uniform" Grid.Row="0" /> 
    <Button Content="Click Me" Click="Button_Click" Grid.Row="1" /> 
    <TextBlock x:Name="txtDecoderType" Grid.Row="2" /> 
    <TextBlock x:Name="txtDecoderContent" Grid.Row="3" /> 
</Grid> 

wichtiger Punkt in meinem Code hier:

Hier ist meine Probe

public MainPage() 
{ 
    this.InitializeComponent(); 
    NavigationCacheMode = NavigationCacheMode.Required; 

    // Useful to know when to initialize/clean up the camera 
    Application.Current.Suspending += Application_Suspending; 
    Application.Current.Resuming += Application_Resuming; 
} 

private async void Button_Click(object sender, RoutedEventArgs e) 
{ 
    _displayOrientation = _displayInformation.CurrentOrientation; 
    _displayInformation.OrientationChanged += DisplayInformation_OrientationChanged; 
    await InitializeCameraAsync(); 
    await _mediaCapture.VideoDeviceController.FocusControl.FocusAsync(); 
    await GetPreviewFrameAsSoftwareBitmapAsync(); 
} 

private readonly DisplayInformation _displayInformation = DisplayInformation.GetForCurrentView(); 
private DisplayOrientations _displayOrientation = DisplayOrientations.Portrait; 

// Rotation metadata to apply to the preview stream (MF_MT_VIDEO_ROTATION) 
// Reference: http://msdn.microsoft.com/en-us/library/windows/apps/xaml/hh868174.aspx 
private static readonly Guid RotationKey = new Guid("C380465D-2271-428C-9B83-ECEA3B4A85C1"); 

// Prevent the screen from sleeping while the camera is running 
private readonly DisplayRequest _displayRequest = new DisplayRequest(); 

// For listening to media property changes 
private readonly SystemMediaTransportControls _systemMediaControls = SystemMediaTransportControls.GetForCurrentView(); 

// MediaCapture and its state variables 
private MediaCapture _mediaCapture; 

private bool _isInitialized = false; 
private bool _isPreviewing = false; 

// Information about the camera device 
private bool _mirroringPreview = false; 

private bool _externalCamera = false; 

private async void Application_Suspending(object sender, SuspendingEventArgs e) 
{ 
    // Handle global application events only if this page is active 
    // See official sample 
} 

private async void Application_Resuming(object sender, object o) 
{ 
    // Handle global application events only if this page is active 
    // See official sample 
} 

protected override async void OnNavigatingFrom(NavigatingCancelEventArgs e) 
{ 
    // Handling of this event is included for completenes, as it will only fire when navigating between pages and this sample only includes one page  
    // See official sample 
} 

private async void SystemMediaControls_PropertyChanged(SystemMediaTransportControls sender, SystemMediaTransportControlsPropertyChangedEventArgs args) 
{ 
    // See official sample 
} 

private async void DisplayInformation_OrientationChanged(DisplayInformation sender, object args) 
{ 
    // See official sample 
} 

private async void MediaCapture_Failed(MediaCapture sender, MediaCaptureFailedEventArgs errorEventArgs) 
{ 
    // See official sample 
} 

private async Task InitializeCameraAsync() 
{ 
    Debug.WriteLine("InitializeCameraAsync"); 

    if (_mediaCapture == null) 
    { 
     // Attempt to get the back camera if one is available, but use any camera device if not 
     var cameraDevice = await FindCameraDeviceByPanelAsync(Windows.Devices.Enumeration.Panel.Back); 

     if (cameraDevice == null) 
     { 
      Debug.WriteLine("No camera device found!"); 
      return; 
     } 

     // Create MediaCapture and its settings 
     _mediaCapture = new MediaCapture(); 

     // Register for a notification when something goes wrong 
     _mediaCapture.Failed += MediaCapture_Failed; 

     var settings = new MediaCaptureInitializationSettings { VideoDeviceId = cameraDevice.Id }; 

     // Initialize MediaCapture 
     try 
     { 
      await _mediaCapture.InitializeAsync(settings); 
      _isInitialized = true; 
     } 
     catch (UnauthorizedAccessException) 
     { 
      Debug.WriteLine("The app was denied access to the camera"); 
     } 

     // If initialization succeeded, start the preview 
     if (_isInitialized) 
     { 
      // Figure out where the camera is located 
      if (cameraDevice.EnclosureLocation == null || cameraDevice.EnclosureLocation.Panel == Windows.Devices.Enumeration.Panel.Unknown) 
      { 
       // No information on the location of the camera, assume it's an external camera, not integrated on the device 
       _externalCamera = true; 
      } 
      else 
      { 
       // Camera is fixed on the device 
       _externalCamera = false; 

       // Only mirror the preview if the camera is on the front panel 
       _mirroringPreview = (cameraDevice.EnclosureLocation.Panel == Windows.Devices.Enumeration.Panel.Front); 
      } 

      await StartPreviewAsync(); 
     } 
    } 
} 

private async Task StartPreviewAsync() 
{ 
    Debug.WriteLine("StartPreviewAsync"); 

    // Prevent the device from sleeping while the preview is running 
    _displayRequest.RequestActive(); 

    // Register to listen for media property changes 
    _systemMediaControls.PropertyChanged += SystemMediaControls_PropertyChanged; 

    // Set the preview source in the UI and mirror it if necessary 
    PreviewControl.Source = _mediaCapture; 
    PreviewControl.FlowDirection = _mirroringPreview ? FlowDirection.RightToLeft : FlowDirection.LeftToRight; 

    // Start the preview 
    await _mediaCapture.StartPreviewAsync(); 
    _isPreviewing = true; 

    // Initialize the preview to the current orientation 
    if (_isPreviewing) 
    { 
     await SetPreviewRotationAsync(); 
    } 
} 

private async Task SetPreviewRotationAsync() 
{ 
    // Only need to update the orientation if the camera is mounted on the device 
    if (_externalCamera) return; 

    // Calculate which way and how far to rotate the preview 
    int rotationDegrees = ConvertDisplayOrientationToDegrees(_displayOrientation); 

    // The rotation direction needs to be inverted if the preview is being mirrored 
    if (_mirroringPreview) 
    { 
     rotationDegrees = (360 - rotationDegrees) % 360; 
    } 

    // Add rotation metadata to the preview stream to make sure the aspect ratio/dimensions match when rendering and getting preview frames 
    var props = _mediaCapture.VideoDeviceController.GetMediaStreamProperties(MediaStreamType.VideoPreview); 
    props.Properties.Add(RotationKey, rotationDegrees); 
    await _mediaCapture.SetEncodingPropertiesAsync(MediaStreamType.VideoPreview, props, null); 
} 

private async Task StopPreviewAsync() 
{ 
    // See official sample 
} 

private async Task GetPreviewFrameAsSoftwareBitmapAsync() 
{ 
    // Get information about the preview 
    var previewProperties = _mediaCapture.VideoDeviceController.GetMediaStreamProperties(MediaStreamType.VideoPreview) as VideoEncodingProperties; 

    // Create the video frame to request a SoftwareBitmap preview frame 
    var videoFrame = new VideoFrame(BitmapPixelFormat.Bgra8, (int)previewProperties.Width, (int)previewProperties.Height); 

    // Capture the preview frame 
    using (var currentFrame = await _mediaCapture.GetPreviewFrameAsync(videoFrame)) 
    { 
     // Collect the resulting frame 
     SoftwareBitmap previewFrame = currentFrame.SoftwareBitmap; 
     WriteableBitmap wbmap = new WriteableBitmap((int)previewProperties.Width, (int)previewProperties.Height); 
     previewFrame.CopyToBuffer(wbmap.PixelBuffer); 
     qrcode(wbmap); 
    } 
} 

private async Task CleanupCameraAsync() 
{ 
    // See official sample 
} 

private static async Task<DeviceInformation> FindCameraDeviceByPanelAsync(Windows.Devices.Enumeration.Panel desiredPanel) 
{ 
    // See official sample 
} 

private static int ConvertDisplayOrientationToDegrees(DisplayOrientations orientation) 
{ 
    // See official sample 
} 

private async void qrcode(WriteableBitmap bmp) 
{ 
    IBarcodeReader reader = new BarcodeReader(); 
    // detect and decode the barcode inside the bitmap 
    var result = reader.Decode(bmp); 
    // do something with the result 
    if (result != null) 
    { 
     txtDecoderType.Text = result.BarcodeFormat.ToString(); 
     txtDecoderContent.Text = result.Text; 
    } 
    else 
    { 
     await GetPreviewFrameAsSoftwareBitmapAsync(); 
    } 
} 

Ich habe diesen Code mit Lumia 950 getestet, es funktioniert schnell und fein manchmal an meiner Seite, aber manchmal kann es den Vorschaurahmen gerade nicht decodieren. Es ist also nur eine einfache Probe hier, nicht 100% korrekt kann in einem formellen Projekt verwendet werden. Was ich getan habe, ist zu versuchen Zxing api mit dem offiziellen Camera preview frame sample zu verwenden, also, wenn Sie irgendwelche Probleme haben, um Vorschaubild zu bekommen, können Sie in dieses Beispiel schauen. Es gibt auch eine Zxing sample for QR code hier, Sie können sie auch herunterladen und überprüfen.

Ergänzung: Sie müssen die Funktionen Internet(Client), Microphone, Webcam in der Manifestdatei aktivieren.