在UWP应用程序中的MediaCapture上绘制图像

using Windows.Graphics.Capture;
using Windows.Media.Capture;
using Windows.Media.MediaProperties;
using Windows.UI.Composition;
using Windows.UI.Xaml;
using Windows.UI.Xaml.Controls;
using Windows.UI.Xaml.Hosting;

private async void StartCapture()
{
    // 创建MediaCapture对象
    MediaCapture mediaCapture = new MediaCapture();
    
    // 初始化MediaCapture对象
    await mediaCapture.InitializeAsync();
    
    // 创建GraphicsCaptureItem对象
    GraphicsCaptureItem captureItem = GraphicsCaptureItem.CreateFromVisual(Window.Current.Content);
    
    // 设置MediaCapture的VideoSource为GraphicsCaptureItem
    mediaCapture.VideoDeviceController.SetMediaStreamPropertiesAsync(MediaStreamType.VideoPreview, captureItem);
    
    // 创建CaptureElement对象
    CaptureElement captureElement = new CaptureElement();
    
    // 设置CaptureElement的Source为MediaCapture
    captureElement.Source = mediaCapture;
    
    // 将CaptureElement添加到UI界面中
    // 这里假设有一个名为"rootGrid"的Grid控件
    rootGrid.Children.Add(captureElement);
    
    // 开始预览
    await mediaCapture.StartPreviewAsync();
    
    // 在MediaCapture上绘制图像
    Compositor compositor = ElementCompositionPreview.GetElementVisual(captureElement).Compositor;
    SpriteVisual spriteVisual = compositor.CreateSpriteVisual();
    spriteVisual.Size = new Vector2((float)captureElement.ActualWidth, (float)captureElement.ActualHeight);
    CompositionBrush brush = compositor.CreateSurfaceBrush();
    brush.Surface = captureItem.Surface;
    spriteVisual.Brush = brush;
    ElementCompositionPreview.SetElementChildVisual(captureElement, spriteVisual);
}