互斥的可检查菜单项? [英] Mutually exclusive checkable menu items?

问题描述

给定以下代码:

<MenuItem x:Name="MenuItem_Root" Header="Root">
    <MenuItem x:Name="MenuItem_Item1" IsCheckable="True" Header="item1" />
    <MenuItem x:Name="MenuItem_Item2" IsCheckable="True" Header="item2"/>
    <MenuItem x:Name="MenuItem_Item3" IsCheckable="True" Header="item3"/>
</MenuItem>

在 XAML 中，有没有办法创建互斥的可检查菜单项?用户在哪里勾选item2，item的1和3自动取消勾选.

In XAML, is there a way to create checkable menuitem's that are mutually exclusive? Where is the user checks item2, item's 1 and 3 are automatically unchecked.

我可以在后面的代码中通过监控菜单上的点击事件、确定哪个项目被选中并取消选中其他菜单项来实现这一点.我认为有一种更简单的方法.

I can accomplish this in the code behind by monitoring the click events on the menu, determining which item was checked, and unchecking the other menuitems. I'm thinking there is an easier way.

有什么想法吗?

推荐答案

这可能不是您要找的，但您可以为 MenuItem 类编写一个扩展，允许您使用类似于 RadioButton 类的 GroupName 属性.我稍微修改了这个 类似扩展的方便示例ToggleButton 控件并根据您的情况对其进行了一些修改，然后想出了这个:

This may not be what you're looking for, but you could write an extension for the MenuItem class that allows you to use something like the GroupName property of the RadioButton class. I slightly modified this handy example for similarly extending ToggleButton controls and reworked it a little for your situation and came up with this:

using System;
using System.Collections.Generic;
using System.Windows;
using System.Windows.Controls;
using System.Windows.Controls.Primitives;

namespace WpfTest
{
     public class MenuItemExtensions : DependencyObject
     {
           public static Dictionary<MenuItem, String> ElementToGroupNames = new Dictionary<MenuItem, String>();

           public static readonly DependencyProperty GroupNameProperty =
               DependencyProperty.RegisterAttached("GroupName",
                                            typeof(String),
                                            typeof(MenuItemExtensions),
                                            new PropertyMetadata(String.Empty, OnGroupNameChanged));

           public static void SetGroupName(MenuItem element, String value)
           {
                element.SetValue(GroupNameProperty, value);
           }

           public static String GetGroupName(MenuItem element)
           {
                return element.GetValue(GroupNameProperty).ToString();
           }

           private static void OnGroupNameChanged(DependencyObject d, DependencyPropertyChangedEventArgs e)
           {
                //Add an entry to the group name collection
                var menuItem = d as MenuItem;

                if (menuItem != null)
                {
                     String newGroupName = e.NewValue.ToString();
                     String oldGroupName = e.OldValue.ToString();
                     if (String.IsNullOrEmpty(newGroupName))
                     {
                          //Removing the toggle button from grouping
                          RemoveCheckboxFromGrouping(menuItem);
                     }
                     else
                     {
                          //Switching to a new group
                          if (newGroupName != oldGroupName)
                          {
                              if (!String.IsNullOrEmpty(oldGroupName))
                              {
                                   //Remove the old group mapping
                                   RemoveCheckboxFromGrouping(menuItem);
                              }
                              ElementToGroupNames.Add(menuItem, e.NewValue.ToString());
                               menuItem.Checked += MenuItemChecked;
                          }
                     }
                }
           }

           private static void RemoveCheckboxFromGrouping(MenuItem checkBox)
           {
                ElementToGroupNames.Remove(checkBox);
                checkBox.Checked -= MenuItemChecked;
           }


           static void MenuItemChecked(object sender, RoutedEventArgs e)
           {
                var menuItem = e.OriginalSource as MenuItem;
                foreach (var item in ElementToGroupNames)
                {
                     if (item.Key != menuItem && item.Value == GetGroupName(menuItem))
                     {
                          item.Key.IsChecked = false;
                     }
                }
           }
      }
 }

然后，在 XAML 中，您将编写:

Then, in the XAML, you'd write:

        <MenuItem x:Name="MenuItem_Root" Header="Root">
            <MenuItem x:Name="MenuItem_Item1" YourNamespace:MenuItemExtensions.GroupName="someGroup" IsCheckable="True" Header="item1" />
            <MenuItem x:Name="MenuItem_Item2" YourNamespace:MenuItemExtensions.GroupName="someGroup" IsCheckable="True" Header="item2"/>
            <MenuItem x:Name="MenuItem_Item3" YourNamespace:MenuItemExtensions.GroupName="someGroup" IsCheckable="True" Header="item3"/>
        </MenuItem>

这有点痛苦，但它提供了一个好处，即不强迫您编写任何额外的过程代码(当然除了扩展类)来实现它.

It's a bit of a pain, but it offers the perk of not forcing you to write any additional procedural code (aside from the extension class, of course) to implement it.

感谢布拉德·坎宁安 (Brad Cunningham)，他创作了原始的 ToggleButton 解决方案.

Credit goes to Brad Cunningham who authored the original ToggleButton solution.

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