public async Task StartScanningAsync(Action <ZXing.Result> scanCallback, MobileBarcodeScanningOptions options = null)
{
if (stopping)
{
var error = "Camera is closing";
OnScannerError?.Invoke(new[] { error });
return;
}
displayRequest.RequestActive();
isAnalyzing = true;
ScanCallback = scanCallback;
ScanningOptions = options ?? MobileBarcodeScanningOptions.Default;
topText.Text = TopText ?? string.Empty;
bottomText.Text = BottomText ?? string.Empty;
if (UseCustomOverlay)
{
gridCustomOverlay.Children.Clear();
if (CustomOverlay != null)
{
gridCustomOverlay.Children.Add(CustomOverlay);
}
gridCustomOverlay.Visibility = Visibility.Visible;
gridDefaultOverlay.Visibility = Visibility.Collapsed;
}
else
{
gridCustomOverlay.Visibility = Visibility.Collapsed;
gridDefaultOverlay.Visibility = Visibility.Visible;
}
// Find which device to use
var preferredCamera = await GetFilteredCameraOrDefaultAsync(ScanningOptions);
if (preferredCamera == null)
{
var error = "No camera available";
System.Diagnostics.Debug.WriteLine(error);
isMediaCaptureInitialized = false;
OnScannerError?.Invoke(new[] { error });
return;
}
if (preferredCamera.EnclosureLocation == null || preferredCamera.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 = preferredCamera.EnclosureLocation.Panel == Windows.Devices.Enumeration.Panel.Front;
}
mediaCapture = new MediaCapture();
// Initialize the capture with the settings above
try
{
await mediaCapture.InitializeAsync(new MediaCaptureInitializationSettings
{
StreamingCaptureMode = StreamingCaptureMode.Video,
VideoDeviceId = preferredCamera.Id
});
isMediaCaptureInitialized = true;
}
catch (UnauthorizedAccessException)
{
System.Diagnostics.Debug.WriteLine("Denied access to the camera");
}
catch (Exception ex)
{
System.Diagnostics.Debug.WriteLine("Exception when init MediaCapture: {0}", ex);
}
if (!isMediaCaptureInitialized)
{
var error = "Unexpected error on Camera initialisation";
OnScannerError?.Invoke(new[] { error });
return;
}
// Set the capture element's source to show it in the UI
captureElement.Source = mediaCapture;
captureElement.FlowDirection = mirroringPreview ? FlowDirection.RightToLeft : FlowDirection.LeftToRight;
try
{
// Start the preview
await mediaCapture.StartPreviewAsync();
}
catch (Exception ex)
{
var error = "Unexpected error on Camera initialisation";
OnScannerError?.Invoke(new[] { error });
return;
}
if (mediaCapture.CameraStreamState == CameraStreamState.Streaming)
{
OnCameraInitialized?.Invoke();
}
// Get all the available resolutions for preview
var availableProperties = mediaCapture.VideoDeviceController.GetAvailableMediaStreamProperties(MediaStreamType.VideoPreview);
var availableResolutions = new List <CameraResolution>();
foreach (var ap in availableProperties)
{
var vp = (VideoEncodingProperties)ap;
System.Diagnostics.Debug.WriteLine("Camera Preview Resolution: {0}x{1}", vp.Width, vp.Height);
availableResolutions.Add(new CameraResolution {
Width = (int)vp.Width, Height = (int)vp.Height
});
}
CameraResolution previewResolution = null;
if (ScanningOptions.CameraResolutionSelector != null)
{
previewResolution = ScanningOptions.CameraResolutionSelector(availableResolutions);
}
if (availableResolutions == null || availableResolutions.Count < 1)
{
var error = "Camera is busy. Try to close all applications that use camera.";
OnScannerError?.Invoke(new[] { error });
return;
}
// If the user did not specify a resolution, let's try and find a suitable one
if (previewResolution == null)
{
// Loop through all supported sizes
foreach (var sps in availableResolutions)
{
// Find one that's >= 640x360 but <= 1000x1000
// This will likely pick the *smallest* size in that range, which should be fine
if (sps.Width >= 640 && sps.Width <= 1000 && sps.Height >= 360 && sps.Height <= 1000)
{
previewResolution = new CameraResolution
{
Width = sps.Width,
Height = sps.Height
};
break;
}
}
}
if (previewResolution == null)
{
previewResolution = availableResolutions.LastOrDefault();
}
if (previewResolution == null)
{
System.Diagnostics.Debug.WriteLine("No preview resolution available. Camera may be in use by another application.");
return;
}
MobileBarcodeScanner.Log("Using Preview Resolution: {0}x{1}", previewResolution.Width, previewResolution.Height);
// Find the matching property based on the selection, again
var chosenProp = availableProperties.FirstOrDefault(ap => ((VideoEncodingProperties)ap).Width == previewResolution.Width && ((VideoEncodingProperties)ap).Height == previewResolution.Height);
// Pass in the requested preview size properties
// so we can set them at the same time as the preview rotation
// to save an additional set property call
await SetPreviewRotationAsync(chosenProp);
// *after* the preview is setup, set this so that the UI layout happens
// otherwise the preview gets stuck in a funny place on screen
captureElement.Stretch = Stretch.UniformToFill;
await SetupAutoFocus();
var zxing = ScanningOptions.BuildBarcodeReader();
timerPreview = new Timer(async(state) =>
{
var delay = ScanningOptions.DelayBetweenAnalyzingFrames;
if (stopping || processing || !isAnalyzing ||
(mediaCapture == null || mediaCapture.CameraStreamState != Windows.Media.Devices.CameraStreamState.Streaming))
{
timerPreview.Change(delay, Timeout.Infinite);
return;
}
processing = true;
SoftwareBitmapLuminanceSource luminanceSource = null;
try
{
// Get preview
var frame = await mediaCapture.GetPreviewFrameAsync(videoFrame);
// Create our luminance source
luminanceSource = new SoftwareBitmapLuminanceSource(frame.SoftwareBitmap);
}
catch (Exception ex)
{
MobileBarcodeScanner.Log("GetPreviewFrame Failed: {0}", ex);
}
ZXing.Result result = null;
try
{
// Try decoding the image
if (luminanceSource != null)
{
result = zxing.Decode(luminanceSource);
}
}
catch (Exception ex)
{
MobileBarcodeScanner.Log("Warning: zxing.Decode Failed: {0}", ex);
}
// Check if a result was found
if (result != null && !string.IsNullOrEmpty(result.Text))
{
if (!ContinuousScanning)
{
delay = Timeout.Infinite;
await Dispatcher.RunAsync(CoreDispatcherPriority.Normal, async() => { await StopScanningAsync(); });
}
else
{
delay = ScanningOptions.DelayBetweenContinuousScans;
}
LastScanResult = result;
ScanCallback(result);
}
processing = false;
timerPreview.Change(delay, Timeout.Infinite);
}, null, ScanningOptions.InitialDelayBeforeAnalyzingFrames, Timeout.Infinite);
}
public async Task StartScanningAsync(Action <ZXing.Result> scanCallback, MobileBarcodeScanningOptions options = null)
{
if (stopping)
{
return;
}
isAnalyzing = true;
ScanCallback = scanCallback;
ScanningOptions = options ?? MobileBarcodeScanningOptions.Default;
topText.Text = TopText ?? string.Empty;
bottomText.Text = BottomText ?? string.Empty;
if (UseCustomOverlay)
{
gridCustomOverlay.Children.Clear();
if (CustomOverlay != null)
{
gridCustomOverlay.Children.Add(CustomOverlay);
}
gridCustomOverlay.Visibility = Visibility.Visible;
gridDefaultOverlay.Visibility = Visibility.Collapsed;
}
else
{
gridCustomOverlay.Visibility = Visibility.Collapsed;
gridDefaultOverlay.Visibility = Visibility.Visible;
}
// Find which device to use
var preferredCamera = await this.GetFilteredCameraOrDefaultAsync(ScanningOptions);
mediaCapture = new MediaCapture();
// Initialize the capture with the settings above
await mediaCapture.InitializeAsync(new MediaCaptureInitializationSettings()
{
StreamingCaptureMode = StreamingCaptureMode.Video,
VideoDeviceId = preferredCamera.Id
});
// Set the capture element's source to show it in the UI
captureElement.Source = mediaCapture;
// Start the preview
await mediaCapture.StartPreviewAsync();
// Get all the available resolutions for preview
var availableProperties = mediaCapture.VideoDeviceController.GetAvailableMediaStreamProperties(MediaStreamType.VideoPreview);
var availableResolutions = new List <CameraResolution>();
foreach (var ap in availableProperties)
{
var vp = (VideoEncodingProperties)ap;
System.Diagnostics.Debug.WriteLine("Camera Preview Resolution: {0}x{1}", vp.Width, vp.Height);
availableResolutions.Add(new CameraResolution {
Width = (int)vp.Width, Height = (int)vp.Height
});
}
CameraResolution previewResolution = null;
if (ScanningOptions.CameraResolutionSelector != null)
{
previewResolution = ScanningOptions.CameraResolutionSelector(availableResolutions);
}
// If the user did not specify a resolution, let's try and find a suitable one
if (previewResolution == null)
{
// Loop through all supported sizes
foreach (var sps in availableResolutions)
{
// Find one that's >= 640x360 but <= 1000x1000
// This will likely pick the *smallest* size in that range, which should be fine
if (sps.Width >= 640 && sps.Width <= 1000 && sps.Height >= 360 && sps.Height <= 1000)
{
previewResolution = new CameraResolution
{
Width = sps.Width,
Height = sps.Height
};
break;
}
}
}
if (previewResolution == null)
{
previewResolution = availableResolutions.LastOrDefault();
}
System.Diagnostics.Debug.WriteLine("Using Preview Resolution: {0}x{1}", previewResolution.Width, previewResolution.Height);
// Find the matching property based on the selection, again
var chosenProp = availableProperties.FirstOrDefault(ap => ((VideoEncodingProperties)ap).Width == previewResolution.Width && ((VideoEncodingProperties)ap).Height == previewResolution.Height);
// Set the selected resolution
await mediaCapture.VideoDeviceController.SetMediaStreamPropertiesAsync(MediaStreamType.VideoPreview, chosenProp);
await SetPreviewRotationAsync();
captureElement.Stretch = Stretch.UniformToFill;
// Get our preview properties
var previewProperties = mediaCapture.VideoDeviceController.GetMediaStreamProperties(MediaStreamType.VideoPreview) as VideoEncodingProperties;
// Setup a frame to use as the input settings
var destFrame = new VideoFrame(Windows.Graphics.Imaging.BitmapPixelFormat.Bgra8, (int)previewProperties.Width, (int)previewProperties.Height);
var zxing = ScanningOptions.BuildBarcodeReader();
timerPreview = new Timer(async(state) => {
var delay = ScanningOptions.DelayBetweenAnalyzingFrames;
if (stopping || processing || !isAnalyzing ||
(mediaCapture == null || mediaCapture.CameraStreamState != Windows.Media.Devices.CameraStreamState.Streaming))
{
timerPreview.Change(delay, Timeout.Infinite);
return;
}
processing = true;
SoftwareBitmapLuminanceSource luminanceSource = null;
try
{
// Get preview
var frame = await mediaCapture.GetPreviewFrameAsync(destFrame);
// Create our luminance source
luminanceSource = new SoftwareBitmapLuminanceSource(frame.SoftwareBitmap);
} catch (Exception ex)
{
System.Diagnostics.Debug.WriteLine("GetPreviewFrame Failed: {0}", ex);
}
ZXing.Result result = null;
try
{
// Try decoding the image
if (luminanceSource != null)
{
result = zxing.Decode(luminanceSource);
}
}
catch (Exception ex)
{
}
// Check if a result was found
if (result != null && !string.IsNullOrEmpty(result.Text))
{
if (!ContinuousScanning)
{
delay = Timeout.Infinite;
await Dispatcher.RunAsync(CoreDispatcherPriority.Normal, async() => { await StopScanningAsync(); });
}
else
{
delay = ScanningOptions.DelayBetweenContinuousScans;
}
LastScanResult = result;
ScanCallback(result);
}
processing = false;
timerPreview.Change(delay, Timeout.Infinite);
}, null, ScanningOptions.InitialDelayBeforeAnalyzingFrames, Timeout.Infinite);
}