wpf - 在 xaml 上设置 GroupStyle 内部样式

Question

我正在尝试为 ContexMenu 设置默认样式，并且我想在样式内将默认 GroupStyle 设置为 ContexMenu。像这样的东西:

<Setter Property="ItemsControl.GroupStyle">
    <Setter.Value>
       <GroupStyle>
          <...>
        </GroupStyle>
    </Setter.Value>
</Setter>

但是编译器说错误:它无法在 ItemsControl 上找到 GroupStyle。

但是，在代码中我可以简单地做:

ContextMenu contextMenu;
contextMenu.GroupStyle.Add(someSavedStyle);

我怎样才能在 xaml 中实现这一点？

提前致谢!

Answer 1

您可以使用附加属性来简化添加组样式:

<Style TargetType="MenuItem">
    <Setter Property="b:GroupStyleEx.Append">
        <Setter.Value>
            <GroupStyle .. />
        </Setter.Value>
    </Setter>

    <!-- you can add as many as you like... -->
    <Setter Property="b:GroupStyleEx.Append">
        <Setter.Value>
            <!-- second group style -->
            <GroupStyle .. />
        </Setter.Value>
    </Setter>
</Style>

这是附加属性的代码:

using System;
using System.Windows;
using System.Windows.Controls;

namespace Util
{
    public static class GroupStyleEx
    {
        public static readonly DependencyProperty AppendProperty
            = DependencyProperty.RegisterAttached("Append", typeof (GroupStyle), typeof (GroupStyleEx),
                                                  new PropertyMetadata(AppendChanged));

        public static GroupStyle GetAppend(DependencyObject obj)
        {
            return (GroupStyle) obj.GetValue(AppendProperty);
        }

        public static void SetAppend(DependencyObject obj, GroupStyle style)
        {
            obj.SetValue(AppendProperty, style);
        }

        private static void AppendChanged(DependencyObject d, DependencyPropertyChangedEventArgs e)
        {
            var itemsControl = d as ItemsControl;
            if (itemsControl == null)
                throw new InvalidOperationException("Can only add GroupStyle to ItemsControl");

            var @new = e.NewValue as GroupStyle;
            if (@new != null)
                itemsControl.GroupStyle.Add(@new);
        }
    }
}