一、WPF路由事件介紹

路由事件的傳播方式

       通過RoutingStrategy來定義傳播的方式

public enum RoutingStrategy
    { 
        Tunnel = 0, //隧道，由頂層元素向內傳播，事件一般以Preview開頭 （由最外層向內傳播）
        Bubble = 1, //冒泡，與隧道相反，向外傳播 （由內向外傳播）
        Direct = 2, //直接，與傳統的事件相似 
    }

WPF中的路由事件用的最多的就是Tunnel和Bubble這兩種傳播方式，所以一般路由事件都是成對出現，

   如：PreviewMouseLeftDown和MouseLeftDown

   注意：Tunnel事件總是比Bubble事件先執行，如果在Tunnel事件中設置了Handled = true,那麼成對的Bubble事件將不會發生，因爲它們共享同一個RoutedEventArgs類的實例，在轉播的過程中設置了Handled = true， 路由事件還是會繼續傳播，只是不會執行。

看一個例子：以下控件都設置了冒泡事件MouseUp，點擊最上面label 事件有  label向上傳遞到window

BubbledLabelClick.xaml

<Window x:Class="RoutedEvents.BubbledLabelClick"
    xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation"
    xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"
    Title="BubbledLabelClick" Height="359" Width="329"
    MouseUp="SomethingClicked"
    >
    <Grid Margin="3" MouseUp="SomethingClicked">
      <Grid.RowDefinitions>
        <RowDefinition Height="Auto"></RowDefinition>
        <RowDefinition Height="*"></RowDefinition>
        <RowDefinition Height="Auto"></RowDefinition>
        <RowDefinition Height="Auto"></RowDefinition>
      </Grid.RowDefinitions>
      
      <Label Margin="5" Background="AliceBlue" BorderBrush="Black" BorderThickness="1" MouseUp="SomethingClicked" HorizontalAlignment="Left" >
        <StackPanel MouseUp="SomethingClicked" >
          <TextBlock Margin="3" MouseUp="SomethingClicked" >
            Image and picture label</TextBlock>
          <Image Source="happyface.jpg" Stretch="None" 
                 MouseUp="SomethingClicked" />
          <TextBlock Margin="3" 
                     MouseUp="SomethingClicked" >
            Courtesy of the StackPanel</TextBlock>
        </StackPanel>
      </Label>

      
      <ListBox Margin="5" Name="lstMessages" Grid.Row="1"></ListBox>
      <CheckBox Margin="5" Grid.Row="2" Name="chkHandle">Handle first event</CheckBox>
      <Button Click="cmdClear_Click" Grid.Row="3" HorizontalAlignment="Right" Margin="5" Padding="3">Clear List</Button>
    </Grid>
</Window>

BubbledLabelClick.cs

using System;
using System.Collections.Generic;
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.Shapes;

namespace RoutedEvents
{
    /// <summary>
    /// Interaction logic for RoutedLabelClick.xaml
    /// </summary>

    public partial class BubbledLabelClick : System.Windows.Window
    {

        public BubbledLabelClick()
        {
            InitializeComponent();
        }

        protected int eventCounter = 0;

        private void SomethingClicked(object sender, RoutedEventArgs e)
        {            
            eventCounter++;
            string message = "#" + eventCounter.ToString() + ":\r\n" + 
                " Sender: " + sender.ToString() + "\r\n" +
                " Source: " + e.Source + "\r\n" +
                " Original Source: " + e.OriginalSource;
            lstMessages.Items.Add(message);
            e.Handled = (bool)chkHandle.IsChecked;//設置Handled=true之後事件就不在傳遞            
        }

        private void cmdClear_Click(object sender, RoutedEventArgs e)
        {            
            eventCounter = 0;
            lstMessages.Items.Clear();
        }
    }
}