屏幕截图 Windows.UI.Core.CoreWindow 沉浸式 UWP

要使用屏幕截图功能，并在 UWP 应用程序中实现沉浸式体验，可以按照以下步骤操作：

1. 在 XAML 页面中添加一个名为 "ImmersiveCanvas" 的 Canvas 控件，用于显示截图。

<Canvas x:Name="ImmersiveCanvas" />

2. 在代码中引入必要的命名空间：

using Windows.Graphics.Capture;
using Windows.Graphics.DirectX;
using Windows.Graphics.Display;
using Windows.UI.Composition;
using Windows.UI.Core;
using Windows.UI.Xaml.Hosting;

3. 在页面的构造函数中初始化截图的相关对象：

private CoreWindow coreWindow;
private GraphicsCaptureItem captureItem;
private CompositionGraphicsDevice compositionGraphicsDevice;
private CompositionDrawingSurface drawingSurface;
private CompositionSurfaceBrush surfaceBrush;

public MainPage()
{
    this.InitializeComponent();

    coreWindow = CoreWindow.GetForCurrentThread();
    captureItem = GraphicsCaptureItem.CreateFromVisual(Window.Current.Content);

    var device = Direct3D11Helper.CreateDevice();
    compositionGraphicsDevice = CanvasComposition.CreateCompositionGraphicsDevice(Window.Current.Compositor, device);

    drawingSurface = compositionGraphicsDevice.CreateDrawingSurface(new Size(Window.Current.Bounds.Width, Window.Current.Bounds.Height), DirectXPixelFormat.B8G8R8A8UIntNormalized, DirectXAlphaMode.Premultiplied);

    surfaceBrush = Window.Current.Compositor.CreateSurfaceBrush(drawingSurface);
    surfaceBrush.Stretch = CompositionStretch.None;

    var visual = Window.Current.Compositor.CreateSpriteVisual();
    visual.Brush = surfaceBrush;

    ElementCompositionPreview.SetElementChildVisual(ImmersiveCanvas, visual);

    coreWindow.SizeChanged += CoreWindow_SizeChanged;
}

4. 添加处理 CoreWindow_SizeChanged 事件的方法，在屏幕尺寸发生改变时更新绘图表面的大小：

private void CoreWindow_SizeChanged(CoreWindow sender, WindowSizeChangedEventArgs args)
{
    drawingSurface.Resize(new Size(coreWindow.Bounds.Width, coreWindow.Bounds.Height));
}

5. 在需要进行截图的地方，调用下面的方法来获取当前屏幕的截图：

private async void CaptureScreen()
{
    using (var screenBitmap = await GraphicsCapture.CreateSnapshotAsync(captureItem))
    using (var screenBitmapSurface = CanvasComposition.CreateCompositionGraphicsDevice(Window.Current.Compositor, screenBitmap))
    using (var screenBitmapDrawingSurface = screenBitmapSurface.CreateDrawingSurface(screenBitmap.Size, DirectXPixelFormat.B8G8R8A8UIntNormalized, DirectXAlphaMode.Premultiplied))
    {
        using (var ds = CanvasComposition.CreateDrawingSession(screenBitmapDrawingSurface))
        {
            ds.Clear(Colors.Transparent);
            ds.DrawImage(screenBitmap);
        }

        using (var drawingSession = drawingSurface.CreateDrawingSession())
        {
            drawingSession.Clear(Colors.Transparent);
            drawingSession.DrawImage(screenBitmapDrawingSurface);
        }
    }
}

以上步骤中，我们使用了 Windows.Graphics.Capture 命名空间提供的功能来进行屏幕截图，并使用了 Windows.UI.Composition 命名空间提供的功能来实现沉浸式体验。