WPF路由事件一：逻辑树和可视树

一、什么是逻辑树

逻辑树就是描述WPF界面元素的实际构成，它是由程序在XAML中所有的UI元素组成。最显著的特点就是由布局控件、或者其他常用的控件组成。

 <Window x:Class="WpfRouteEvent.MainWindow"

         xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation"

         xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"

         Title="MainWindow" Height="" Width="">

     <Grid>

         <StackPanel>

             <TextBox></TextBox>

         </StackPanel>

     </Grid>

 </Window>

从上面的代码中可以看出，Window、Grid、StackPanel、TextBox其实就是XAML界面的逻辑树。

二、什么是可视树

可视树是由界面上可见的元素构成的，这些元素主要是由从Visual或者Visual3D类中派生出来的类。

上面代码中的Window、Grid、StackPanel、TextBox它们本身就包含一些由Visual或者Visual3D类派生出的一些可视树的元素来组成的。

三、逻辑树和可视树的遍历

逻辑树遍历使用LogicalTreeHelper类。
可视树遍历使用VisualTreeHelper类。

演示遍历逻辑树和可视树

1、XAML界面左边显示逻辑树，右边显示可视树，代码如下：

 <Window x:Class="WpfRouteEvent.MainWindow"

         xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation"

         xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"

         Title="MainWindow" Height="" Width="">

     <Grid>

         <DockPanel>

             <Button DockPanel.Dock="Top" Click="Button_Click" Content="获取逻辑树和可视树"></Button>

             <Grid>

                 <Grid.ColumnDefinitions>

                     <ColumnDefinition></ColumnDefinition>

                     <ColumnDefinition></ColumnDefinition>

                 </Grid.ColumnDefinitions>

                 <DockPanel Grid.Column="">

                     <TextBlock DockPanel.Dock="Top" Text="逻辑树"></TextBlock>

                     <TreeView Name="tvLogicTree"></TreeView>

                 </DockPanel>

                 <DockPanel Grid.Column="">

                     <TextBlock DockPanel.Dock="Top" Text="可视树"></TextBlock>

                     <TreeView Name="tvVisualTree"></TreeView>

                 </DockPanel>

             </Grid>

         </DockPanel>

     </Grid>

 </Window>

2、添加类，用于遍历整个XAML界面的逻辑树和可视树

 using System;

 using System.Collections.Generic;

 using System.Linq;

 using System.Text;

 using System.Threading.Tasks;

 using System.Windows;

 using System.Windows.Controls;

 using System.Windows.Media;

 namespace WpfRouteEvent

 {

     public class WpfTreeHelper

     {

         static string GetTypeDescription(object obj)

         {

             return obj.GetType().FullName;

         }

         /// <summary>

         /// 获取逻辑树

         /// </summary>

         /// <param name="obj"></param>

         /// <returns></returns>

         public static TreeViewItem GetLogicTree(DependencyObject obj)

         {

             if (obj == null)

             {

                 return null;

             }

             //创建逻辑树的节点

             TreeViewItem treeItem = new TreeViewItem {Header=GetTypeDescription(obj),IsExpanded=true };

             //循环遍历，获取逻辑树的所有子节点

             foreach (var child in LogicalTreeHelper.GetChildren(obj))

             {

                 //递归调用

                 var item = GetLogicTree(child as DependencyObject);

                 if (item != null)

                 {

                     treeItem.Items.Add(item);

                 }

             }

             return treeItem;

         }

         /// <summary>

         /// 获取可视树

         /// </summary>

         /// <param name="obj"></param>

         /// <returns></returns>

         public static TreeViewItem GetVisualTree(DependencyObject obj)

         {

             if (obj == null)

             {

                 return null;

             }

             TreeViewItem treeItem = new TreeViewItem { Header=GetTypeDescription(obj),IsExpanded=true};

             for (int i = ; i < VisualTreeHelper.GetChildrenCount(obj); i++)

             {

                 var child = VisualTreeHelper.GetChild(obj, i);

                 var item = GetVisualTree(child);

                 if (item != null)

                 {

                     treeItem.Items.Add(item);

                 }

             }

             return treeItem;

         }

     }

 }

3、在按钮的点击事件中将获取的逻辑树和可视树添加到XAML界面中

 using System;

 using System.Collections.Generic;

 using System.Linq;

 using System.Text;

 using System.Threading.Tasks;

 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 WpfRouteEvent

 {

     /// <summary>

     /// MainWindow.xaml 的交互逻辑

     /// </summary>

     public partial class MainWindow : Window

     {

         public MainWindow()

         {

             InitializeComponent();

         }

         private void Button_Click(object sender, RoutedEventArgs e)

         {

             this.tvLogicTree.Items.Add(WpfTreeHelper.GetLogicTree(this));

             this.tvVisualTree.Items.Add(WpfTreeHelper.GetVisualTree(this));

         }

     }

 }

4、点击按钮，界面运行效果