.NET Core 3.1 WPF中GraphicsCapturePicker跨线程调用异常求助

我正在开发基于.NET Core 3.1的WPF解决方案，需求是选择多个捕获窗口，在窗口聚焦时进行共享。目前已通过列表实现基础功能，但想通过带窗口预览的GraphicsCapturePicker优化用户体验，却遇到以下异常：

The application called an interface that was marshalled for a different thread

相关代码 #

打开选择器的方法代码 #

public async void OpenCapturePicker(object sender, RoutedEventArgs e)
{
    Console.WriteLine("OpenCapturePicker");
    await Dispatcher.InvokeAsync(OpenCapturePicker);

}
private async void OpenCapturePicker()
{
    var picker = new GraphicsCapturePicker();

    picker.SetWindow(_capturableWindowHandle);
    var item = await picker.PickSingleItemAsync();
    if (item == null) return;
    //rest of code
}

_capturableWindowHandle的构造函数定义 #

public SomeClass(){
 _capturableWindowHandle = new WindowInteropHelper(this).Handle;
}

支持SetWindow方法的扩展类 #

public  static class CaptureHelper
{
    static readonly Guid GraphicsCaptureItemGuid = new Guid("79C3F95B-31F7-4EC2-A464-632EF5D30760");
    public static GraphicsCaptureItem CreateItemForWindow(IntPtr windowInteropHandler)
    {
        var factory = WindowsRuntimeMarshal.GetActivationFactory(typeof(GraphicsCaptureItem));
        var interop = (IGraphicsCaptureItemInterop) factory;
        var itemPointer = interop.CreateForWindow(windowInteropHandler, GraphicsCaptureItemGuid);
        var item = Marshal.GetObjectForIUnknown(itemPointer) as GraphicsCaptureItem;
        Marshal.Release(itemPointer);

        return item;
    }
    public static void SetWindow(this GraphicsCapturePicker picker, IntPtr hwnd)
    {
        var interop = (IInitializeWithWindow)(object)picker;
        interop.Initialize(hwnd);
    }
}

更新 #

功能开发分支链接：GitHub分支

解决思路 #

• 修复递归调用问题：当前事件处理方法OpenCapturePicker(sender, e)中调用Dispatcher.InvokeAsync(OpenCapturePicker)会触发无限制递归，这是线程混乱的核心原因之一。应拆分核心逻辑，明确线程调度：

  public async void OpenCapturePicker(object sender, RoutedEventArgs e)
  {
      Console.WriteLine("OpenCapturePicker");
      if (!Dispatcher.CheckAccess())
      {
          await Dispatcher.InvokeAsync(OpenCapturePickerCore);
          return;
      }
      await OpenCapturePickerCore();
  }
  
  private async Task OpenCapturePickerCore()
  {
      var picker = new GraphicsCapturePicker();
      picker.SetWindow(_capturableWindowHandle);
      var item = await picker.PickSingleItemAsync();
      if (item == null) return;
      // 后续处理逻辑
  }
  

• 强制UI线程执行COM操作：GraphicsCapturePicker及相关COM接口（如IInitializeWithWindow）必须在UI线程调用。通过Dispatcher.CheckAccess()判断当前线程，确保所有选择器相关操作都在UI线程执行。

• 避免滥用async void：除事件处理方法外，异步逻辑尽量返回Task而非void，便于控制异步流程，减少线程上下文混乱。

• 延迟获取窗口句柄：构造函数阶段窗口HWND可能未完全初始化，应在窗口加载完成后获取句柄：

  protected override void OnSourceInitialized(EventArgs e)
  {
      base.OnSourceInitialized(e);
      _capturableWindowHandle = new WindowInteropHelper(this).Handle;
  }
  

内容的提问来源于stack exchange，提问作者Vinicius Andrade