C# 为画布上的重叠矩形触发MouseDown事件

我有一个WPF窗口，其中包含一个画布，在代码中填充了旋转的矩形。每个矩形都有一个MouseDown事件，它们的位置将根据用户提供的坐标分布。通常两个或多个会重叠，部分阻碍其下方的矩形

我需要在按下鼠标时为鼠标下的每个矩形触发MouseDown事件，即使该矩形被另一个矩形阻挡，但我只为最上面的矩形获取MouseDown事件

我曾尝试为单击的矩形设置e.Handled，并在画布上路由事件，但运气不佳，甚至尝试根据鼠标下方的对象坐标定位对象，但矩形的旋转使得这一点难以计算

    public MainWindow()
    {
        InitializeComponent();

        Rectangle r1 = new Rectangle() {Width = 80, Height = 120, Fill = Brushes.Blue };
        r1.MouseDown += r_MouseDown;
        RotateTransform rt1 = new RotateTransform(60);
        r1.RenderTransform = rt1;
        Canvas.SetLeft(r1, 150);
        Canvas.SetTop(r1, 50);
        canvas1.Children.Add(r1);

        Rectangle r2 = new Rectangle() { Width = 150, Height = 50, Fill = Brushes.Green };
        r2.MouseDown += r_MouseDown;
        RotateTransform rt2 = new RotateTransform(15);
        r2.RenderTransform = rt2;
        Canvas.SetLeft(r2, 100);
        Canvas.SetTop(r2, 100);
        canvas1.Children.Add(r2);
    }


    private void r_MouseDown(object sender, MouseButtonEventArgs e)
    {
        Console.WriteLine("Rectangle Clicked");
    }
}

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还有一个问题与此类似，但没有公认的答案，也不清楚解决这个问题的最终解决方案是什么。让我们看看能不能更清楚一点

首先，下面概述的解决方案将使用

VisualTreeHelper.HitTest

方法来识别鼠标是否单击了矩形。VisualTreeHelper允许我们查找矩形，即使它们由于

Canvas.SetTop

和各种

.RenderTransform

操作而移动

其次，我们将在画布元素而不是单个矩形上捕获单击事件。这允许我们在画布级别处理事情，并一次检查所有矩形

public MainWindow()
    {
        InitializeComponent();
        //Additional rectangle for testing.
        Rectangle r3 = new Rectangle() { Width = 175, Height = 80, Fill = Brushes.Goldenrod };
        Canvas.SetLeft(r3, 80);
        Canvas.SetTop(r3, 80);
        canvas1.Children.Add(r3);

        Rectangle r1 = new Rectangle() { Width = 80, Height = 120, Fill = Brushes.Blue };
        RotateTransform rt1 = new RotateTransform(60);
        r1.RenderTransform = rt1;
        Canvas.SetLeft(r1, 100);
        Canvas.SetTop(r1, 100);
        canvas1.Children.Add(r1);

        Rectangle r2 = new Rectangle() { Width = 150, Height = 50, Fill = Brushes.Green };
        RotateTransform rt2 = new RotateTransform(15);
        r2.LayoutTransform = rt2;
        Canvas.SetLeft(r2, 100);
        Canvas.SetTop(r2, 100);
        canvas1.Children.Add(r2);
        //Mouse 'click' event.
        canvas1.PreviewMouseDown += canvasMouseDown;
    }

    //list to store the hit test results
    private List<HitTestResult> hitResultsList = new List<HitTestResult>();

上面的测试示例只显示了一个消息框，当鼠标指针被单击时，它显示了鼠标指针下所有矩形的填充颜色；验证VisualTreeHelper是否确实检索了堆栈中的所有矩形

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与您的要求非常相似。此解决方案非常有效。我曾希望有一个简单一点的东西存在，但这确实起到了作用，我可以从中得到我需要的信息。谢谢@Stewbob。是的，当我看到你的问题时，我想，“哦，我知道怎么做”，然后花了半天的时间意识到这并不容易。多重形状，尤其是对象上的变换，需要使用VisualTreeHelper，这使得它有点麻烦。

    private void canvasMouseDown(object sender, MouseButtonEventArgs e)
    {
        if (canvas1.Children.Count > 0)
        {
            // Retrieve the coordinates of the mouse position.
            Point pt = e.GetPosition((UIElement)sender);

            // Clear the contents of the list used for hit test results.
            hitResultsList.Clear();

            // Set up a callback to receive the hit test result enumeration.
            VisualTreeHelper.HitTest(canvas1,
                                new HitTestFilterCallback(MyHitTestFilter),
                                new HitTestResultCallback(MyHitTestResult),
                                new PointHitTestParameters(pt));

            // Perform actions on the hit test results list.
            if (hitResultsList.Count > 0)
            {
                string msg = null;
                foreach (HitTestResult htr in hitResultsList)
                {
                    Rectangle r = (Rectangle)htr.VisualHit;
                    msg += r.Fill.ToString() + "\n";
                }
                //Message displaying the fill colors of all the rectangles 
                //under the mouse when it was clicked.
                MessageBox.Show(msg);
            }
        }
    }

    // Filter the hit test values for each object in the enumeration.
    private HitTestFilterBehavior MyHitTestFilter(DependencyObject o)
    {
        // Test for the object value you want to filter.
        if (o.GetType() == typeof(Label))
        {
            // Visual object and descendants are NOT part of hit test results enumeration.
            return HitTestFilterBehavior.ContinueSkipSelfAndChildren;
        }
        else
        {
            // Visual object is part of hit test results enumeration.
            return HitTestFilterBehavior.Continue;
        }
    }

   // Add the hit test result to the list of results.
    private HitTestResultBehavior MyHitTestResult(HitTestResult result)
    {
        //Filter out the canvas object.
        if (!result.VisualHit.ToString().Contains("Canvas"))
        {
            hitResultsList.Add(result);
        }
        // Set the behavior to return visuals at all z-order levels.
        return HitTestResultBehavior.Continue;
    }