<Grid x:Name="LayoutRoot"  Background="Black">        <Grid Background="Black">            <Grid.ColumnDefinitions>                <ColumnDefinition Width="50"/>                <ColumnDefinition Width="300"/>                <ColumnDefinition Width="50"/>            </Grid.ColumnDefinitions>            <Grid Grid.Column="0" Height="366" Margin="0,0,0,0">            </Grid>            <!--取景器区域-->            <Grid Grid.Column="1" x:Name="ScanViewGrid" Margin="0,0,0,0">                <Grid.Resources>                    <Storyboard x:Name="myStoryboard">                        <DoubleAnimation                                    Storyboard.TargetName="imgScan"                                    Storyboard.TargetProperty="(Canvas.Top)"                                    Duration="0:0:2.5"                                    From="0"                                    To="300"                                    RepeatBehavior="Forever"/>                    </Storyboard>                </Grid.Resources>                <!--扫描线-->                                    <Canvas Width="300"  Canvas.Top="170"  Height="300">                        <CaptureElement  Stretch="UniformToFill" x:Name="VideoCapture"  Width="300" Height="300"  >                                                 </CaptureElement>                        <Image x:Name="imgScan" Source="/Assets/img/light.png"  Width="300" Height="40" Stretch="Fill"/>                        <Image x:Name="CaptureImage" Width="300" Height="300"  Visibility="Collapsed" />                    </Canvas>                                    </Grid>            <Grid Grid.Column="2" Margin="0,0,0,0"/>        </Grid>              <TextBlock x:Name="Error" VerticalAlignment="Bottom" FontSize="32" Width="400" TextAlignment="Center" />        <TextBlock x:Name="ScanResult" Text="hhh" FontSize="25" Foreground="White" VerticalAlignment="Bottom" TextAlignment="Center" Width="400"/>    </Grid> 

  public sealed partial class QCodeView : Page    {        private readonly MediaCapture _mediaCapture = new MediaCapture();        private Result _result;        private NavigationHelper navigationHelper;        private ObservableDictionary defaultViewModel = new ObservableDictionary();        private DispatcherTimer _timer;              public QCodeView()        {            this.InitializeComponent();            //设备屏幕方向            DisplayInformation.AutoRotationPreferences = DisplayOrientations.Portrait;            ///隐藏StatusBar            var statusBar = StatusBar.GetForCurrentView();            statusBar.HideAsync();            this.navigationHelper = new NavigationHelper(this);            this.navigationHelper.LoadState += this.NavigationHelper_LoadState;            this.navigationHelper.SaveState += this.NavigationHelper_SaveState;        }        /// <summary>        /// 获取与此 <see cref="Page"/> 关联的 <see cref="NavigationHelper"/>。        /// </summary>        public NavigationHelper NavigationHelper        {            get { return this.navigationHelper; }        }        /// <summary>        /// 获取此 <see cref="Page"/> 的视图模型。        /// 可将其更改为强类型视图模型。        /// </summary>        public ObservableDictionary DefaultViewModel        {            get { return this.defaultViewModel; }        }        /// <summary>        /// 使用在导航过程中传递的内容填充页。  在从以前的会话        /// 重新创建页时，也会提供任何已保存状态。        /// </summary>        /// <param name="sender">        /// 事件的来源; 通常为 <see cref="NavigationHelper"/>        /// </param>        /// <param name="e">事件数据，其中既提供在最初请求此页时传递给        /// <see cref="Frame.Navigate(Type, Object)"/> 的导航参数，又提供        /// 此页在以前会话期间保留的状态的        /// 字典。 首次访问页面时，该状态将为 null。</param>        private void NavigationHelper_LoadState(object sender, LoadStateEventArgs e)        {        }        /// <summary>        /// 保留与此页关联的状态，以防挂起应用程序或        /// 从导航缓存中放弃此页。值必须符合        /// <see cref="SuspensionManager.SessionState"/> 的序列化要求。        /// </summary>        /// <param name="sender">事件的来源；通常为 <see cref="NavigationHelper"/></param>        ///<param name="e">提供要使用可序列化状态填充的空字典        ///的事件数据。</param>        private void NavigationHelper_SaveState(object sender, SaveStateEventArgs e)        {        }        #region NavigationHelper 注册        /// <summary>        /// 此部分中提供的方法只是用于使        /// NavigationHelper 可响应页面的导航方法。        /// <para>        /// 应将页面特有的逻辑放入用于        /// <see cref="NavigationHelper.LoadState"/>        /// 和 <see cref="NavigationHelper.SaveState"/> 的事件处理程序中。        /// 除了在会话期间保留的页面状态之外        /// LoadState 方法中还提供导航参数。        /// </para>        /// </summary>        /// <param name="e">提供导航方法数据和        /// 无法取消导航请求的事件处理程序。</param>        protected  override void OnNavigatedTo(NavigationEventArgs e)        {                      myStoryboard.Begin();            InitVideoCapture();            InitVideoTimer();                            this.navigationHelper.OnNavigatedTo(e);        }        /// <summary>        /// 初始化摄像        /// </summary>        private async void InitVideoCapture()        {            ///摄像头的检测            var cameras = await DeviceInformation.FindAllAsync(DeviceClass.VideoCapture);            if (cameras.Count < 1)            {                Error.Text = "设备没有摄像头,读取本地资源";                await DecodeStaticResource();                return;            }                       ///  创建 MediaCaptureInitializationSettings 对象的新实例。            var settings = new MediaCaptureInitializationSettings            {                StreamingCaptureMode = StreamingCaptureMode.AudioAndVideo,                MediaCategory = MediaCategory.Other,                AudioProcessing = Windows.Media.AudioProcessing.Default,                VideoDeviceId = cameras[1].Id            };            //if (cameras.Count == 1)            //{            //    settings = new MediaCaptureInitializationSettings { VideoDeviceId = cameras[0].Id }; // 0 => front, 1 => back            //}            //else            //{            //    settings = new MediaCaptureInitializationSettings { VideoDeviceId = cameras[1].Id }; // 0 => front, 1 => back            //}            await _mediaCapture.InitializeAsync(settings);            VideoCapture.Source = _mediaCapture;            await _mediaCapture.StartPreviewAsync();        }        private void InitVideoTimer()        {            _timer = new DispatcherTimer();            _timer.Interval = TimeSpan.FromSeconds(6);            _timer.Tick += _timer_Tick;            _timer.Start();        }        private bool IsBusy = false;        async void _timer_Tick(object sender, object e)        {            try            {                while (_result == null)                {                    if (!IsBusy)                    {                        IsBusy = true;                        ///获取焦点                        //var autoFocusSupported = _mediaCapture.VideoDeviceController.FocusControl.SupportedFocusModes.Contains(FocusMode.Auto);                        //if (autoFocusSupported)                        //{                        //    var focusSettings = new FocusSettings                        //    {                        //        Mode = FocusMode.Auto,                        //        AutoFocusRange = AutoFocusRange.Normal                        //    };                        //    _mediaCapture.VideoDeviceController.FocusControl.Configure(focusSettings);                        //    //await _mediaCapture.VideoDeviceController.FocusControl.FocusAsync().AsTask(_cancellationTokenSource.Token);                        //}                        var photoStorageFile = await KnownFolders.PicturesLibrary.CreateFileAsync("qcode.jpg", CreationCollisionOption.ReplaceExisting);                        await _mediaCapture.CapturePhotoToStorageFileAsync(ImageEncodingProperties.CreateJpeg(), photoStorageFile);                        var stream = await photoStorageFile.OpenReadAsync();                        // initialize with 1,1 to get the current size of the image                        var writeableBmp = new WriteableBitmap(1, 1);                        writeableBmp.SetSource(stream);                        // and create it again because otherwise the WB isn‘t fully initialized and decoding                        // results in a IndexOutOfRange                        writeableBmp = new WriteableBitmap(writeableBmp.PixelWidth, writeableBmp.PixelHeight);                        stream.Seek(0);                        writeableBmp.SetSource(stream);                        _result = ScanBitmap(writeableBmp);                        await photoStorageFile.DeleteAsync(StorageDeleteOption.PermanentDelete);                    }                    if (_result != null)                    {                        await _mediaCapture.StopPreviewAsync();                        VideoCapture.Visibility = Visibility.Collapsed;                        CaptureImage.Visibility = Visibility.Visible;                        ScanResult.Text = _result.Text;                        _timer.Stop();                        myStoryboard.Stop();                        imgScan.Visibility = Visibility.Collapsed;                                           }                      IsBusy = false;                                 }            }            catch (Exception ex)            {                               IsBusy = false;                //Error.Text = ex.Message;            }        }        /// <summary>        /// 读取本地资源        /// </summary>        /// <returns></returns>        private async System.Threading.Tasks.Task DecodeStaticResource()        {            var file = await Windows.ApplicationModel.Package.Current.InstalledLocation.GetFileAsync(@"Assets\1.png");            var stream = await file.OpenReadAsync();            // initialize with 1,1 to get the current size of the image            var writeableBmp = new WriteableBitmap(1, 1);            writeableBmp.SetSource(stream);            // and create it again because otherwise the WB isn‘t fully initialized and decoding            // results in a IndexOutOfRange            writeableBmp = new WriteableBitmap(writeableBmp.PixelWidth, writeableBmp.PixelHeight);            stream.Seek(0);            writeableBmp.SetSource(stream);            CaptureImage.Source = writeableBmp;            VideoCapture.Visibility = Visibility.Collapsed;            CaptureImage.Visibility = Visibility.Visible;            _result = ScanBitmap(writeableBmp);            if (_result != null)            {                ScanResult.Text += _result.Text;            }            return;        }        /// <summary>        /// 解析二维码图片        /// </summary>        /// <param name="writeableBmp">拍摄的图片</param>        /// <returns></returns>        private Result ScanBitmap(WriteableBitmap writeableBmp)        {            var barcodeReader = new BarcodeReader            {                TryHarder = true,                AutoRotate = true            };            var result = barcodeReader.Decode(writeableBmp);            if (result != null)            {                CaptureImage.Source = writeableBmp;            }            return result;        }        /// <summary>        /// 页面离开时对_mediaCapture对象进行释放         /// 防止内存溢出及资源占用        /// </summary>        /// <param name="e"></param>        protected override async void OnNavigatedFrom(NavigationEventArgs e)        {            try            {                await _mediaCapture.StopPreviewAsync();                await _mediaCapture.StopRecordAsync();                _mediaCapture.Dispose();            }            catch (Exception)            {            }            this.navigationHelper.OnNavigatedFrom(e);        }        #endregion    }