uwp之拍照（使用后置摄像头）

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">

            <Slider

                x: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" />

                <Button

                    Margin="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 filename

                string 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 = ;

                }

                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 { }

        }