TwoWay绑定PointCollection

Question

我试图使用WPF模拟一种简单的类似CAD的行为，其中多边形被绘制到画布上，并且多边形的点可以移动。

我设法得到它，以便通过为集合中的每个Point设置一个带有Ellipse的ItemsControl，在画布上显示PointCollection属性。多边形正确显示，因此我知道Binding正在使用Source-To-Target。我已经设置了一些简单的活动，以便能够选择＆＃39;多边形的点，并移动它们。事件工作正常，多边形确实在画布上发生变化。但是，我对点位置所做的任何更改都不会被推送到源属性。

有关如何让Binding在相反方向上工作的任何线索？这种事情（ItemsControl中的双向绑定）是否可能？或许还有另一种方法！

由于

XAML

<Canvas Width="500" Height="300" MouseMove="MoveMouse">
    <ItemsControl ItemsSource="{Binding Path=MyPath, Mode=TwoWay, NotifyOnSourceUpdated=True }">
        <ItemsControl.ItemTemplate>
            <DataTemplate>
                <Canvas>
                    <Ellipse Width="20"
                             Height="20"
                             Canvas.Left="{Binding Path=X, Mode=TwoWay, NotifyOnSourceUpdated=True }"
                             Canvas.Top="{Binding Path=Y, Mode=TwoWay, NotifyOnSourceUpdated=True }"
                             Fill="Red"
                             Margin="-10,-10,0,0"
                             MouseDown="ClickPoint" />
                </Canvas>
            </DataTemplate>
        </ItemsControl.ItemTemplate>
    </ItemsControl>
</Canvas>

MainWindow.cs

public partial class MainWindow : Window
{
    public PointCollection MyPath { get; set; } = new PointCollection{ new Point(10, 10), new Point(100, 100), new Point(200, 100) };

    public Ellipse selectedPoint;

    public MainWindow()
    {
        InitializeComponent();
    }

    private void MoveMouse(object sender, MouseEventArgs e)
    {
        if (selectedPoint == null) return;

        //Move selected point to mouse position
        selectedPoint.SetValue(Canvas.LeftProperty, e.GetPosition(sender as UIElement).X);
        selectedPoint.SetValue(Canvas.TopProperty, e.GetPosition(sender as UIElement).Y);

        //Print out MyPath points to check if source has changed
        Console.WriteLine("");
        foreach (Point p in MyPath)
            Console.Write(p + " - ");
    }

    private void ClickPoint(object sender, MouseButtonEventArgs e)
    {
        //Pick up point, if no point is currently selected
        selectedPoint = selectedPoint == null ? (Ellipse)sender : null;
    }
}