如何处理来自子窗口的路由事件

Question

意图是从子窗口获取和处理路由事件。我不能（阅读：不想）使用直接路由，因为（命令）之间有更多元素。

以下示例说明事件路由无法从一个窗口运行到第二个窗口。 子窗口 XAML：

<Window x:Class="WpfApplication1.Window1"
    xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation"
    xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"
    Title="Window1" Height="300" Width="300">
<Grid>
    <Button Content="Raise Routing Event" HorizontalAlignment="Left" Margin="50" VerticalAlignment="Top"
            Width="150" Click="RaiseRoutedEvent" />
</Grid>

引发事件代码：

using System.Windows;

namespace WpfApplication1
{
    public partial class Window1
    {
        private static readonly RoutedEvent ChildWindowEvent = EventManager.RegisterRoutedEvent("ButtonClicked",
            RoutingStrategy.Bubble, typeof(RoutedEventHandler), typeof(Window1));

        public Window1()
        {
            InitializeComponent();
        }

        public event RoutedEventHandler ButtonClicked
        {
            add { AddHandler(ChildWindowEvent, value); }
            remove { RemoveHandler(ChildWindowEvent, value); }
        }

        private void RaiseRoutedEvent(object sender, RoutedEventArgs e)
        {
            RoutedEventArgs eventArgs = new RoutedEventArgs(ChildWindowEvent);
            RaiseEvent(eventArgs);
        }
    }
}

主窗口：

<Window x:Class="WpfApplication1.MainWindow"
        xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation"
        xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"
        xmlns:wpfApplication1="clr-namespace:WpfApplication1"
        Title="MainWindow" Height="350" Width="525" wpfApplication1:Window1.ButtonClicked="HandleRoutedEvent">
    <Grid>
        <Button Content="Open new window" HorizontalAlignment="Left" Margin="50" VerticalAlignment="Top"
                Width="150" Click="OpenNewWindow" />
    </Grid>
</Window>

应该处理路由事件的窗口：

using System.Windows;

namespace WpfApplication1
{
    public partial class MainWindow
    {
        public MainWindow()
        {
            InitializeComponent();
        }

        private void OpenNewWindow(object sender, RoutedEventArgs e)
        {
            Window1 window1 = new Window1();
            window1.ShowDialog();
        }

        private void HandleRoutedEvent(object sender, RoutedEventArgs e)
        {
            MessageBox.Show("This message is shown from the Main Window");
        }
    }
}

该事件是从 Window1 引发的，但 MainWindow.HandleRoutedEvent 未达到其断点。为什么？

Answer 1

路由事件沿着可视化树传播。顶级窗口是可视树根，不是其所有者可视树的一部分。因此，从子窗口中冒出的任何事件都不会传播到所有者窗口。

顺便说一句，我注意到您的示例代码中有几个问题。在您的 xaml 中，您使用附加的事件语法注册了一个处理程序，但您已经声明了一个实例事件。如果要实现附加事件，则需要这些成员：

public static readonly RoutedEvent ButtonClickedEvent = EventManager.RegisterCrossWindowRoutedEvent(
    "ButtonClicked",
    RoutingStrategy.Bubble,
    typeof(RoutedEventHandler),
    typeof(ChildWindow));

public static void AddButtonClickedHandler(UIElement target, RoutedEventHandler handler)
{
    target.AddHandler(ButtonClickedEvent, handler);
}

public static void RemoveButtonClickedHandler(UIElement target, RoutedEventHandler handler)
{
    target.RemoveHandler(ButtonClickedEvent, handler);
}

如果您打算创建实例事件，则事件名称应与注册路由事件时提供的名称相对应（“ButtonClicked”）。