1 private async void InitMediaCaptureAsync()
 2         {
 3             //寻找后置摄像头
 4             var allVideoDevices = await DeviceInformation.FindAllAsync(DeviceClass.VideoCapture);
 5             var cameraDevice = allVideoDevices.FirstOrDefault(x => x.EnclosureLocation != null && x.EnclosureLocation.Panel == Windows.Devices.Enumeration.Panel.Back);
 6
 7             if (cameraDevice == null)
 8             {
 9                 Debug.WriteLine("No camera device found!");
10
11                 return;
12             }
13
14             var settings = new MediaCaptureInitializationSettings
15             {
16                 StreamingCaptureMode = StreamingCaptureMode.Video,
17                 //必须，否则截图的时候会很卡很慢
18                 PhotoCaptureSource = PhotoCaptureSource.VideoPreview,
19                 VideoDeviceId = cameraDevice.Id
20             };
21
22             _mediaCapture = new MediaCapture();
23
24             try
25             {
26                 await _mediaCapture.InitializeAsync(settings);
27                 _initialized = true;//初始化成功
28             }
29             catch (UnauthorizedAccessException)
30             {
31                 Debug.WriteLine("The app was denied access to the camera");
32             }
33             catch (Exception ex)
34             {
35                 Debug.WriteLine("Exception when initializing MediaCapture with {0}: {1}", cameraDevice.Id, ex.ToString());
36             }
37
38             if (_initialized)
39             {
40                 var focusControl = _mediaCapture.VideoDeviceController.FocusControl;
41
42                 if (focusControl.Supported)
43                 {
44                     var focusSettings = new FocusSettings()
45                     {
46                         Mode = focusControl.SupportedFocusModes.FirstOrDefault(f => f == FocusMode.Continuous),
47                         DisableDriverFallback = true,
48                         AutoFocusRange = focusControl.SupportedFocusRanges.FirstOrDefault(f => f == AutoFocusRange.FullRange),
49                         Distance = focusControl.SupportedFocusDistances.FirstOrDefault(f => f == ManualFocusDistance.Nearest)
50                     };
51
52                     //设置聚焦，最好使用FocusMode.Continuous，否则影响截图会很模糊，不利于识别
53                     focusControl.Configure(focusSettings);
54                 }
55
56                 captureElement.Source = _mediaCapture;
57                 captureElement.FlowDirection = FlowDirection.LeftToRight;
58
59                 try
60                 {
61                     await _mediaCapture.StartPreviewAsync();
62                     _previewing = true;
63                 }
64                 catch (Exception ex)
65                 {
66                     Debug.WriteLine("Exception when starting the preview: {0}", ex.ToString());
67                 }
68
69                 if (_previewing)
70                 {
71                     try
72                     {
73                         if (_mediaCapture.VideoDeviceController.FlashControl.Supported)
74                         {
75                             //关闭闪光灯
76                             _mediaCapture.VideoDeviceController.FlashControl.Enabled = false;
77                         }
78                     }
79                     catch
80                     {
81                     }
82
83                     if (focusControl.Supported)
84                     {
85                         //开始聚焦
86                         await focusControl.FocusAsync();
87                     }
88                 }
89             }
90         }

1 private void InitTimer()
2         {
3             _timer = new DispatcherTimer();
4             //每50毫秒截一次图
5             _timer.Interval = TimeSpan.FromMilliseconds(50);
6             _timer.Tick += _timer_Tick;
7             _timer.Start();
8         }

 1 private async void _timer_Tick(object sender, object e)
 2         {
 3             using (var stream = new InMemoryRandomAccessStream())
 4             {
 5                 var previewProperties = _mediaCapture.VideoDeviceController.GetMediaStreamProperties(MediaStreamType.VideoPreview) as VideoEncodingProperties;
 6                 //将截图写入内存流中
 7                 await _mediaCapture.CapturePhotoToStreamAsync(ImageEncodingProperties.CreateJpeg(), stream);
 8
 9                 //利用Zxing识别，成功：停止timer；失败：继续
10                 var reader = new BarcodeReader();
11                 var bitmapWriteable = new WriteableBitmap((int)previewProperties.Width, (int)previewProperties.Height);
12                 bitmapWriteable.SetSource(stream);
13                 var result = reader.Decode(bitmapWriteable);
14
15                 if (!string.IsNullOrEmpty(result.Text))
16                 {
17                     _timer.Stop();
18                 }
19             }
20         }

 1 private async void _timer_Tick(object sender, object e)
 2         {
 3             var previewProperties = _mediaCapture.VideoDeviceController.GetMediaStreamProperties(MediaStreamType.VideoPreview) as VideoEncodingProperties;
 4
 5             using (var videoFrame = new VideoFrame(BitmapPixelFormat.Rgba8, (int)previewProperties.Width, (int)previewProperties.Height))
 6             {
 7                 using (var currentFrame = await _mediaCapture.GetPreviewFrameAsync(videoFrame))
 8                 {
 9                     using (var previewFrame = currentFrame.SoftwareBitmap)
10                     {
11                         var buffer = new Windows.Storage.Streams.Buffer((uint)(4 * previewFrame.PixelWidth * previewFrame.PixelHeight));
12                         previewFrame.CopyToBuffer(buffer);
13
14                         using (var stream = buffer.AsStream().AsRandomAccessStream())
15                         {
16                             //利用Zxing识别，成功：停止timer；失败：继续
17                             var reader = new BarcodeReader();
18                             var bitmapWriteable = new WriteableBitmap((int)previewProperties.Width, (int)previewProperties.Height);
19                             bitmapWriteable.SetSource(stream);
20                             var result = reader.Decode(bitmapWriteable);
21
22                             if (!string.IsNullOrEmpty(result.Text))
23                             {
24                                 _timer.Stop();
25                             }
26                         }
27                     }
28                 }
29             }
30         }