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);
        }
예제 #3
0
 public void ScanContinuously(MobileBarcodeScanningOptions options, Action <Result> scanHandler)
 {
     scannerControl.ContinuousScanning = true;
     scannerControl.StartScanning(scanHandler, options ?? Parameters?.Options);
 }