如何获取WPF上下文菜单的原始右键点击坐标（无需手动弹出菜单）？

可以实现，不用接管控件的右键事件手动弹出菜单，以下是两种可行方案：

方案1：利用ContextMenu的Opening事件记录坐标 #

这种方式只需少量代码配合绑定即可实现：

1. 在XAML中给ContextMenu添加Opening事件处理：

<ContextMenu x:Key="PolyCtxMenu" Opening="PolyCtxMenu_Opening">
    <MenuItem Command="{Binding AddVertexCmd}" 
              CommandParameter="{Binding RightClickPosition}" />
</ContextMenu>

2. 在后台代码的Opening事件中，获取右键点击的相对坐标（以目标控件为基准），并赋值给ViewModel的属性：

private void PolyCtxMenu_Opening(object sender, RoutedEventArgs e)
{
    var contextMenu = sender as ContextMenu;
    var targetControl = contextMenu.PlacementTarget as PolyControl;
    if (targetControl != null)
    {
        // 获取相对于PolyControl的鼠标坐标
        var pos = Mouse.GetPosition(targetControl);
        // 假设你的ViewModel有一个名为RightClickPosition的Point类型属性
        var vm = targetControl.DataContext as YourViewModel;
        vm.RightClickPosition = pos;
    }
}

3. 确保你的ViewModel中定义了RightClickPosition属性（实现INotifyPropertyChanged）：

private Point _rightClickPosition;
public Point RightClickPosition
{
    get => _rightClickPosition;
    set
    {
        _rightClickPosition = value;
        OnPropertyChanged();
    }
}

方案2：纯XAML绑定（利用附加属性） #

如果希望尽量少写后台代码，可以通过自定义附加属性来捕获右键坐标：

1. 创建一个附加属性类：

public static class MousePositionHelper
{
    public static readonly DependencyProperty RightClickPositionProperty =
        DependencyProperty.RegisterAttached(
            "RightClickPosition",
            typeof(Point),
            typeof(MousePositionHelper),
            new PropertyMetadata(new Point()));

    public static Point GetRightClickPosition(DependencyObject obj)
    {
        return (Point)obj.GetValue(RightClickPositionProperty);
    }

    public static void SetRightClickPosition(DependencyObject obj, Point value)
    {
        obj.SetValue(RightClickPositionProperty, value);
    }

    // 监听控件的PreviewMouseRightButtonDown事件来记录坐标
    public static readonly DependencyProperty TrackRightClickPositionProperty =
        DependencyProperty.RegisterAttached(
            "TrackRightClickPosition",
            typeof(bool),
            typeof(MousePositionHelper),
            new PropertyMetadata(false, OnTrackRightClickPositionChanged));

    public static bool GetTrackRightClickPosition(DependencyObject obj)
    {
        return (bool)obj.GetValue(TrackRightClickPositionProperty);
    }

    public static void SetTrackRightClickPosition(DependencyObject obj, bool value)
    {
        obj.SetValue(TrackRightClickPositionProperty, value);
    }

    private static void OnTrackRightClickPositionChanged(DependencyObject d, DependencyPropertyChangedEventArgs e)
    {
        var element = d as UIElement;
        if (element == null) return;

        if ((bool)e.NewValue)
        {
            element.PreviewMouseRightButtonDown += Element_PreviewMouseRightButtonDown;
        }
        else
        {
            element.PreviewMouseRightButtonDown -= Element_PreviewMouseRightButtonDown;
        }
    }

    private static void Element_PreviewMouseRightButtonDown(object sender, MouseButtonEventArgs e)
    {
        var element = sender as UIElement;
        if (element != null)
        {
            var pos = e.GetPosition(element);
            SetRightClickPosition(element, pos);
        }
    }
}

2. 在XAML中使用这个附加属性：

<PolyControl ContextMenu="{StaticResource PolyCtxMenu}"
             local:MousePositionHelper.TrackRightClickPosition="True" />

<ContextMenu x:Key="PolyCtxMenu">
    <MenuItem Command="{Binding AddVertexCmd}"
              CommandParameter="{Binding PlacementTarget.(local:MousePositionHelper.RightClickPosition), 
                                        RelativeSource={RelativeSource AncestorType=ContextMenu}}" />
</ContextMenu>

这种方式通过附加属性自动监听目标控件的右键按下事件，记录坐标，然后在MenuItem中通过RelativeSource绑定到PlacementTarget（即PolyControl）的附加属性值，无需手动处理菜单的Opening事件。

内容的提问来源于stack exchange，提问作者Joe