WPF利用VisualTreeHelper遍历寻找对象的指定子级对象或者指定父级对象

转载 https://www.cnblogs.com/dotnetHui/p/8342398.html

微软在VisualTreeHelper类中，提供了一些实用工具方法，用于执行涉及可视化树中的节点的常规任务，VisualTreeHelper 类中的一些方法可以接受表示任意一种可视对象类型的 DependencyObject 值。 
　　这里我们将要用到两个方法分别是：VisualTreeHelper.GetChild()和VisualTreeHelper.GetParent()。

使用VisualTreeHelper

模拟场景搭建

　　新建一个WPF工程，命名为VisualTreeHelperDemo。 
　　假设我们有如下如所示的一个主窗体，窗体的内容容器为一个name=”TopGrid”的Grid控件，它包含了上下两个子级Grid，每个子级Grid中各自包含了一个Button。 
　　 
　　MainWindow.xaml代码如下:　　

<Window x:Class="VisualTreeHelper.MainWindow"
        xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation"
        xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"
        Title="MainWindow" Height="350" Width="525">
    <Grid Name="TopGrid">
        <Grid.RowDefinitions>
            <RowDefinition></RowDefinition>
            <RowDefinition></RowDefinition>
        </Grid.RowDefinitions>
        <Grid >
            <Button Content="Button1" Name="btn_One" VerticalAlignment="Center" HorizontalAlignment="Center">
            </Button>
        </Grid>
        <Grid  Grid.Row="1">
            <Button Content="Button2" Name="btn_Two" VerticalAlignment="Center" HorizontalAlignment="Center">
            </Button>
        </Grid>
    </Grid>
</Window>

　　MainWindow.xaml代码如下:

<Window x:Class="VisualTreeHelper.MainWindow"
        xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation"
        xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"
        Title="MainWindow" Height="350" Width="525">
    <Grid Name="TopGrid">
        <Grid.RowDefinitions>
            <RowDefinition></RowDefinition>
            <RowDefinition></RowDefinition>
        </Grid.RowDefinitions>
        <Grid >
            <Button Content="Button1" Name="btn_One" VerticalAlignment="Center" HorizontalAlignment="Center">
            </Button>
        </Grid>
        <Grid  Grid.Row="1">
            <Button Content="Button2" Name="btn_Two" VerticalAlignment="Center" HorizontalAlignment="Center">
            </Button>
        </Grid>
    </Grid>
</Window>

遍历寻找子级对象

　　现在我们来寻找TopGrid所有Button子级对象，并输出它们的名称。 
　　打开MainWindow.xaml.cs文件，添加寻找子级对象的代码如下：

/// <summary>
/// 利用visualtreehelper寻找对象的子级对象
/// </summary>
/// <typeparam name="T"></typeparam>
/// <param name="obj"></param>
/// <returns></returns>
List<T> FindVisualChild<T>(DependencyObject obj) where T : DependencyObject
{
    try
    {
        List<T> TList = new List<T> { };
        for (int i = 0; i < VisualTreeHelper.GetChildrenCount(obj); i++)
        {
            DependencyObject child = VisualTreeHelper.GetChild(obj, i);
            if (child != null && child is T)
            {
                TList.Add((T)child);
                List<T> childOfChildren = FindVisualChild<T>(child);
                if (childOfChildren != null)
                {
                    TList.AddRange(childOfChildren);
                }
            }
            else
            {
                List<T> childOfChildren = FindVisualChild<T>(child);
                if (childOfChildren != null)
                {
                    TList.AddRange(childOfChildren);
                }
            }
        }
        return TList;
    }
    catch (Exception ee)
    {
        MessageBox.Show(ee.Message);
        return null;
    }
}

　　在btn_One_Click事件里面书写代码如下：

/// <summary>
/// 窗体加载事件
/// </summary>
/// <param name="sender"></param>
/// <param name="e"></param>
private void btn_One_Click(object sender, RoutedEventArgs e)
{
    string btnName = "";
    List<Button> btnList = FindVisualChild<Button>(TopGrid);
    foreach (Button item in btnList)
    {
        btnName += string.IsNullOrEmpty(btnName) ? item.Name.ToString() : "," + item.Name.ToString();
    }
    Show(string.Format(TopGrid.Name.ToString()+"共有{0}个Button,名称分别为{1}", btnList.Count, btnName));
}

运行程序，点击Button1，结果如下图： 

遍历寻找父级对象

　　现在我们来遍历Button2的父级对象，获得其所有父级对象的信息，并且展示。 
　　打开MainWindow.xaml.cs文件，添加寻找父级对象的代码如下：

/// <summary>
/// 利用VisualTreeHelper寻找指定依赖对象的父级对象
/// </summary>
/// <typeparam name="T"></typeparam>
/// <param name="obj"></param>
/// <returns></returns>
public static List<T> FindVisualParent<T>(DependencyObject obj) where T : DependencyObject
{
    try
    {
        List<T> TList = new List<T> { };
        DependencyObject parent = VisualTreeHelper.GetParent(obj);
        if (parent != null && parent is T)
        {
            TList.Add((T)parent);
            List<T> parentOfParent = FindVisualParent<T>(parent);
            if (parentOfParent !=null)
            {
                TList.AddRange(parentOfParent);
            }
        }
        else if ( parent != null )
        {
             List<T> parentOfParent = FindVisualParent<T>(parent);
             if (parentOfParent != null)
             {
                 TList.AddRange(parentOfParent);
             }
        }
        return TList;
    }
    catch (Exception ee)
    {
        MessageBox.Show(ee.Message);
        return null;
    }
}

　　在btn_Two_Click中添加代码如下：

/// <summary>
/// 遍历Button2父级对象信息
/// </summary>
/// <param name="sender"></param>
/// <param name="e"></param>
private void btn_Two_Click(object sender, RoutedEventArgs e)
{
    string parentName = "";
    List<Grid> gridList = FindVisualParent<Grid>(btn_Two);
    foreach (Grid item in gridList)
    {
        parentName += string.IsNullOrEmpty(parentName) ? item.Name.ToString() : "," + item.Name.ToString();
    }
    MessageBox.Show(string.Format(btn_Two.Name.ToString() + "共有{0}个逻辑父级,名称分别为{1}", gridList.Count, parentName));
}

运行程序，点击Button2，效果如下： 
 
　　结果表明遍历成功。

总结

标签：父级,对象,List,指定,TList,null,VisualTreeHelper
来源： https://www.cnblogs.com/JerryZhang320/p/15054350.html