参考:wp8.1之拍照（获取焦点，使用后置摄像头）
uwp开启摄像头要借助CaptureElement呈现来自捕获设备（如照相机或网络摄像机）的流。今天讲讲如何打开摄像头，获取焦点，以及拍照。废话不多说，下面直接上代码。当然前提是一定要记住在appxmanifest文件Capabilities选项选择Webcam,不然会报错
首先 XAML代码：
<Grid Background="{ThemeResource ApplicationPageBackgroundThemeBrush}"><Grid><CaptureElement x:Name="capturePreview" Stretch="UniformToFill" /><Image Name="ProfilePic" /></Grid><StackPanel VerticalAlignment="Bottom"><Sliderx:Name="FocusValueSlider"Margin="12,0,15,0"Header="焦点调节:"LargeChange="25"Maximum="1000"Minimum="0"SmallChange="1"ValueChanged="FocusValueSlider_ValueChanged"Value="500" /><StackPanel Orientation="Horizontal"><Button Click="PhotographButton_Click" Content="启动摄像头" /><ButtonMargin="50,0,0,0"Click="CapturePhoto_Click"Content="拍照" /></StackPanel></StackPanel></Grid>
//启动摄像头async private void PhotographButton_Click(object sender, RoutedEventArgs e){if (captureManager == null){capturePreview.Visibility = Visibility.Visible;ProfilePic.Visibility = Visibility.Collapsed;captureManager = new MediaCapture();//选择后置摄像头var cameraDevice = await FindCameraDeviceByPanelAsync(Windows.Devices.Enumeration.Panel.Back);if (cameraDevice == null){System.Diagnostics.Debug.WriteLine("No camera device found!");return;}var settings = new MediaCaptureInitializationSettings{StreamingCaptureMode = StreamingCaptureMode.Video,//MediaCategory = MediaCategory.Other,//AudioProcessing = AudioProcessing.Default,//PhotoCaptureSource = PhotoCaptureSource.Photo,AudioDeviceId = string.Empty,VideoDeviceId = cameraDevice.Id};await captureManager.InitializeAsync(settings);//摄像头旋转90度//captureManager.SetPreviewRotation(VideoRotation.Clockwise90Degrees);capturePreview.Source = captureManager;await captureManager.StartPreviewAsync();}}private static async Task<DeviceInformation> FindCameraDeviceByPanelAsync(Windows.Devices.Enumeration.Panel desired){var allVideoDevices = await DeviceInformation.FindAllAsync(DeviceClass.VideoCapture);DeviceInformation desiredDevice = allVideoDevices.FirstOrDefault(x => x.EnclosureLocation != null && x.EnclosureLocation.Panel == desired);return desiredDevice ?? allVideoDevices.FirstOrDefault();}//拍照async private void CapturePhoto_Click(object sender, RoutedEventArgs e){if (captureManager != null){capturePreview.Visibility = Visibility.Collapsed;ProfilePic.Visibility = Visibility.Visible;ProfilePic.Source = null;//declare string for filenamestring captureFileName = string.Empty;//图片格式ImageEncodingProperties format = ImageEncodingProperties.CreateJpeg();//创建本地存储文件夹StorageFile file = await ApplicationData.Current.LocalFolder.CreateFileAsync("Photo"+DateTime.Now.ToString("yyMMddHHmmss")+".jpg",CreationCollisionOption.ReplaceExisting);await captureManager.CapturePhotoToStorageFileAsync(format, file);BitmapImage bmpImage = new BitmapImage(new Uri(file.Path));ProfilePic.Source = bmpImage;//释放摄像头资源capturePreview.Visibility = Visibility.Visible;ProfilePic.Visibility = Visibility.Collapsed;//captureManager.Dispose();//captureManager = null; }}private void FocusValueSlider_ValueChanged(object sender, RangeBaseValueChangedEventArgs e){try{uint focus = Convert.ToUInt32(e.NewValue);SetFocus(focus);}catch{}}//设置摄像头焦点方法private async void SetFocus(uint? focusValue = null){try{if (!focusValue.HasValue){focusValue = 500;}if (captureManager.VideoDeviceController.FocusControl.Supported){captureManager.VideoDeviceController.FlashControl.AssistantLightEnabled = false;captureManager.VideoDeviceController.FocusControl.Configure(new FocusSettings() { Mode = FocusMode.Manual, Value = focusValue, DisableDriverFallback = true });await captureManager.VideoDeviceController.FocusControl.FocusAsync();}}catch { }}
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