public async void StartScanning(Action <Result> scanCallback, MobileBarcodeScanningOptions options = null)
{
await StartScanningAsync(scanCallback, options);
}
public async Task StartScanningAsync(Action <Result> scanCallback, MobileBarcodeScanningOptions options)
{
if (stopping)
{
return;
}
displayRequest.RequestActive();
isAnalyzing = true;
ScanCallback = scanCallback;
ScanningOptions = options;
topText.Text = TopText ?? string.Empty;
bottomText.Text = BottomText ?? string.Empty;
// Find which device to use
var preferredCamera = await GetFilteredCameraOrDefaultAsync(ScanningOptions);
if (preferredCamera == null)
{
System.Diagnostics.Debug.WriteLine("No camera available");
isMediaCaptureInitialized = false;
return;
}
if (preferredCamera.EnclosureLocation == null || preferredCamera.EnclosureLocation.Panel == Windows.Devices.Enumeration.Panel.Unknown)
{
}
else
{
// 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)
{
return;
}
// 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)
.Cast <VideoEncodingProperties>();
VideoEncodingProperties previewResolution = null;
// Loop through all supported sizes
foreach (var sps in availableProperties)
{
// 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 = sps;
break;
}
}
if (previewResolution == null)
{
previewResolution = availableProperties.LastOrDefault();
}
if (previewResolution == null)
{
throw new Exception("No preview resolution available. Camera may be in use by another application.");
}
// Find the matching property based on the selection, again
var chosenProp = availableProperties.FirstOrDefault(ap => ap.Width == previewResolution.Width && 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 = 300;
if (stopping || processing || !isAnalyzing ||
(mediaCapture == null || mediaCapture.CameraStreamState != 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 { }
Result result = null;
try
{
// Try decoding the image
if (luminanceSource != null)
{
result = zxing.Decode(luminanceSource);
}
}
catch { }
// 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, 300, Timeout.Infinite);
}
public void ScanContinuously(MobileBarcodeScanningOptions options, Action <Result> scanHandler)
{
scannerControl.ContinuousScanning = true;
scannerControl.StartScanning(scanHandler, options ?? Parameters?.Options);
}
