如何在Adorner层下触发事件

Question

我想点击Adorner层下的按钮。当然，在可视树中，Adorner与控件是不同的分支。Not able to handle PreviewMouseDown

如何在装饰层下触发事件？

xaml在下面。

<Canvas Name="_canvas" Width="100" Height="100">
    <Button Name="_btn" Width="120" Height="120"/>
</Canvas>

代码隐藏在下面。

public partial class MainWindow : Window
{
    public MainWindow()
    {
        InitializeComponent();
        Loaded += delegate { AdornerLayer.GetAdornerLayer(_canvas).Add(new GrayAdorner(_canvas)); };

        _btn.Click += (sender, e) => MessageBox.Show("Mouse Click is working.");
    }
}

public class GrayAdorner : Adorner
{
    public GrayAdorner(UIElement element)
        : base(element) { }

    protected override void OnRender(DrawingContext drawingContext)
    {
        drawingContext.DrawRectangle(Brushes.Gray, null, new Rect(new Point(0, 0), DesiredSize));
        base.OnRender(drawingContext);
    }
}

Answer 1

如果不需要Adorner被测试，请将GrayAdorner的GrayAdorner属性设置为false。鼠标事件将忽略Adorner并传递到下面的Button。

Answer 2

对于带有子控件的Adorner (需要为IsHitTestVisible =True)尝试这样做：

private void AdornerChildMouseDown(object sender, MouseButtonEventArgs e)
    {
        Adorner parentAdorner = VisualTreeHelper.GetParent(sender as DependencyObject) as Adorner;

        Trace.WriteLine("Adorner Child clicked");
        parentAdorner.Visibility = Visibility.Collapsed;

        Task.Factory.StartNew(() =>
        {
            Application.Current.Dispatcher.BeginInvoke(new Action(() =>
            {
                UIElement underMouse = Mouse.DirectlyOver as UIElement;
                if (underMouse != null) underMouse.RaiseEvent(e);
            }));
        });
    }