上下文菜单在某些情况下被剪裁

Question

我目前正在制作一个从左键单击而不是右键单击打开的上下文菜单，为此，我通过处理这样的 ContextMenuOpening 事件来禁止右键单击

private void PinBorder_ContextMenuOpening(object sender, System.Windows.Controls.ContextMenuEventArgs e)
{
    e.Handled = true;
}

，并且我自己根据对 MouseButtonLeftDown 事件的反应打开上下文菜单：

private void PinBorder_MouseLeftButtonDown(object sender, System.Windows.Input.MouseButtonEventArgs e)
{
    PinBorder.ContextMenu.PlacementTarget = PinBorder;
    PinBorder.ContextMenu.Placement = System.Windows.Controls.Primitives.PlacementMode.Center;
    PinBorder.ContextMenu.HorizontalOffset = 0;
    PinBorder.ContextMenu.VerticalOffset = 0;
    PinBorder.ContextMenu.IsOpen = true;
    e.Handled = true;
}

这里的问题是，当第一次打开 ContextMenu 时，一切顺利，但是如果我将一个项目添加到绑定到上下文菜单的可观察集合中并尝试重新打开它，上下文菜单将被裁剪为之前的大小（如果我尝试使用向上/向下键移动上下文菜单选择我可以猜测已经创建了一个条目，但我看不到它，因为它被剪裁了）。

我尝试删除点击抑制的东西，在这种情况下一切都很顺利。

我在 .net Framework 3.5 中读到过这样的问题，但我的目标是 4.0。

有人有解决办法吗？

Answer 1

您可以以这种方式模拟事件：

        ContextMenuAutomationPeer peer = new ContextMenuAutomationPeer(Menu);

        IExpandCollapseProvider invokeProv = peer.GetPattern(PatternInterface.ExpandCollapse) as IExpandCollapseProvider;

        invokeProv.Expand();

然而，使用 UIAutomation 并不简单（我的示例实际上不起作用，但应该为您指明正确的方向）。

您还可以尝试将类似的内容添加到您已有的内容中（在函数之前）：

        ContextMenuAutomationPeer peer = new ContextMenuAutomationPeer(Menu);

        peer.RaiseAutomationEvent(AutomationEvents.MenuOpened);

有用的 msdn 参考。

Answer 2

如果最终找到了一种解决方法来获得我想要的东西，即使该解决方案必须分配比所需更多的内存。

每次必须打开上下文菜单时，我都会重新创建整个上下文菜单。

private void PinBorder_MouseLeftButtonUp(object sender, System.Windows.Input.MouseButtonEventArgs e)
{
    PropertyInputPin.UpdateCompatibleAdjusters();

    PinBorder.ContextMenu = new System.Windows.Controls.ContextMenu();

    Binding binding = new Binding("CompatibleAdjusters");
    binding.Mode = BindingMode.OneWay;
    binding.Source = DataContext;
    BindingOperations.SetBinding(PinBorder.ContextMenu, ContextMenu.ItemsSourceProperty, binding);

    PinBorder.ContextMenu.PlacementTarget = PinBorder;
    PinBorder.ContextMenu.Placement = System.Windows.Controls.Primitives.PlacementMode.Center;
    PinBorder.ContextMenu.HorizontalOffset = 0;
    PinBorder.ContextMenu.VerticalOffset = 0;
    PinBorder.ContextMenu.IsOpen = true;

    for (int i = 0; i < PropertyInputPin.CompatibleAdjusters.Count; i++)
    {
        MenuItem mi = PinBorder.ContextMenu.ItemContainerGenerator.ContainerFromIndex(i) as MenuItem;
        mi.Click += ContextMenu_Click;
    }

    e.Handled = false;
}

Answer 3

我不确定你做错了什么。以下内容符合我的要求：

<Window x:Class="WpfApplication2.MainWindow"
        xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation"
        xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"
        xmlns:local="clr-namespace:WpfApplication2"
        Title="MainWindow" Height="350" Width="525" x:Name="mainWindow">
    <Window.DataContext>
        <local:Class1></local:Class1>
    </Window.DataContext>
    <Grid x:Name="grid" Background="Blue" MouseLeftButtonDown="Grid_MouseLeftButtonDown" ContextMenuOpening="grid_ContextMenuOpening">
        <Grid.RowDefinitions>
            <RowDefinition Height="200"/>
            <RowDefinition Height="Auto"/>
        </Grid.RowDefinitions>
        <Grid.ContextMenu>
            <ContextMenu x:Name="contextMenu" ItemsSource="{Binding menuItems}">
            </ContextMenu>
        </Grid.ContextMenu>
        <Button Height="100" Command="{Binding TestCommand}" Grid.Row="1"></Button>
    </Grid>
</Window>


using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;
using System.Windows;
using System.Windows.Controls;
using System.Windows.Data;
using System.Windows.Documents;
using System.Windows.Input;
using System.Windows.Media;
using System.Windows.Media.Imaging;
using System.Windows.Navigation;
using System.Windows.Shapes;

namespace WpfApplication2
{
    /// <summary>
    /// Interaction logic for MainWindow.xaml
    /// </summary>
    public partial class MainWindow : Window
    {

        private List<MenuItem> list;

        public List<MenuItem> menuItems
        {
            get { return list; }
            set { list = value; }
        }

        public MainWindow()
        {
            InitializeComponent();

            list = new List<MenuItem>();
            MenuItem item = new MenuItem();
            item.Header = "One";
            list.Add(item);
            item = new MenuItem();
            item.Header = "Two";
            list.Add(item);
            item = new MenuItem();
            item.Header = "Three";
            list.Add(item);
        }

        private void Button_Click(object sender, RoutedEventArgs e)
        {
            MenuItem item = new MenuItem();
            item.Header = "Four";
            menuItems.Add(item);
            contextMenu.Items.Add(item);
        }

        private void Grid_MouseLeftButtonDown(object sender, MouseButtonEventArgs e)
        {
            grid.ContextMenu.PlacementTarget = grid;
            grid.ContextMenu.Placement = System.Windows.Controls.Primitives.PlacementMode.Center;
            grid.ContextMenu.HorizontalOffset = 0;
            grid.ContextMenu.VerticalOffset = 0;
            grid.ContextMenu.IsOpen = true;
            e.Handled = true;
        }

        private void grid_ContextMenuOpening(object sender, ContextMenuEventArgs e)
        {
            e.Handled = true;
        }
    }
}

ViewModel：

using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;
using System.Windows.Controls;
using System.Windows;
using System.Windows.Input;
using Microsoft.Practices.Prism.Commands;

namespace WpfApplication2
{
    public class Class1
    {

        private List<MenuItem> list;

        public List<MenuItem> menuItems
        {
            get { return list; }
            set { list = value; }
        }

        public string test
        {
            get;
            set;
        }

        public Class1()
        {
            test = "1";

            list = new List<MenuItem>();
            MenuItem item = new MenuItem();
            item.Header = "One";
            list.Add(item);
            item = new MenuItem();
            item.Header = "Two";
            list.Add(item);
            item = new MenuItem();
            item.Header = "Three";
            list.Add(item);
            TestCommand = new DelegateCommand(Button_Click);
        }

        public ICommand TestCommand{get;private set;}

        private void Button_Click()
        {
            MenuItem item = new MenuItem();
            item.Header = "Four";
            menuItems.Add(item);
        }
    }
}