TreeView.ItemContainerGenerator.ContainerFromItem返回null非根项目。解决方法？ [英] TreeView.ItemContainerGenerator.ContainerFromItem returns null for nonroot items. Workaround?

问题描述

在下面的示例中，当我选择字符串，在窗口的标题变为空。但我的必须的获得字符串的容器。具体来说，我想要做的的SelectedItem = NULL 相当于（但该属性是只读的 TreeView控件，所以我M好一会容器设置其 IsSelected 到假）。 ？怎么办

 <窗口x：类=WpfApplication1.Window1的xmlns =http://schemas.microsoft .COM / WinFX的/ 2006 / XAML /演示的xmlns：X =http://schemas.microsoft.com/winfx/2006/xaml> 
< Window.Resources> 
< X：数组的xmlns =CLR的命名空间：系统;装配= mscorlib程序X：键=阵列TYPE =对象> 
< X：ArrayExtension类型=对象> 
<串GT;串LT; /字符串> 
< / X：ArrayExtension> 
< / X：数组> 
< /Window.Resources> 
<树视图的ItemsSource ={StaticResource的阵列}SelectedItemChanged =处理程序> 
< TreeView.ItemTemplate> 
< HierarchicalDataTemplate的ItemsSource ={结合}> 
< TextBlock的文本=阵列/> 
< HierarchicalDataTemplate.ItemTemplate> 
<&DataTemplate的GT; 
< TextBlock的文本={结合}/> 
< / DataTemplate中> 
< /HierarchicalDataTemplate.ItemTemplate> 
< / HierarchicalDataTemplate> 
< /TreeView.ItemTemplate> 
< / TreeView的> 
  

 命名空间WpfApplication1 
 {
公共部分类窗口1：窗口
 {
公共窗口1（）
 {
的InitializeComponent（）; 
} 
 
私人无效处理程序（对象发件人，EventArgs五）
 {
变种的TreeView =发件人为树视图; 
 VAR容器= treeView.ItemContainerGenerator.ContainerFromItem（treeView.SelectedItem）; 
标题=容器！= NULL？ container.ToString（）：空; 
} 
} 
} 
  

解决方案

的问题是，每个树型视图本身就是一个的ItemsControl ，使他们各自管理自己的容器为他们的孩子

然而，有一个非常简单的方法做你想做的事：不是注册到 SelectedItemChanged 事件中，注册到 TreeViewItem.Selected 事件，将冒泡与 OriginalSource 设置为选定<$ C $ 。C>树型视图

XAML：

 <树视图的ItemsSource ={StaticResource的阵列}TreeViewItem.Selected =TreeViewItem_Selected> 
  

后面的代码：

 私人无效TreeViewItem_Selected（对象发件人，RoutedEventArgs E）{
的TreeViewItem容器=（树型视图）e.OriginalSource; 
标题=容器！= NULL？ container.ToString（）：空; 
} 
  

In the following sample, when I select "String", the title of the window turns to "null". But I must obtain the container of "String". Specifically, I want to do the equivalent of SelectedItem = null (but that property is read only for TreeView, so I'm trying to get to the container to set its IsSelected to false). What to do?

<Window x:Class="WpfApplication1.Window1" xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation" xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml">
    <Window.Resources>
        <x:Array xmlns="clr-namespace:System;assembly=mscorlib" x:Key="Array" Type="Object">
            <x:ArrayExtension Type="Object">
                <String>String</String>
            </x:ArrayExtension>
        </x:Array>
    </Window.Resources>
    <TreeView ItemsSource="{StaticResource Array}" SelectedItemChanged="Handler">
        <TreeView.ItemTemplate>
            <HierarchicalDataTemplate ItemsSource="{Binding}">
                <TextBlock Text="Array"/>
                <HierarchicalDataTemplate.ItemTemplate>
                    <DataTemplate>
                        <TextBlock Text="{Binding}"/>
                    </DataTemplate>
                </HierarchicalDataTemplate.ItemTemplate>
            </HierarchicalDataTemplate>
        </TreeView.ItemTemplate>
    </TreeView>

namespace WpfApplication1
{
    public partial class Window1 : Window
    {
        public Window1()
        {
            InitializeComponent();
        }

        private void Handler(object sender, EventArgs e)
        {
            var treeView = sender as TreeView;
            var container = treeView.ItemContainerGenerator.ContainerFromItem(treeView.SelectedItem);
            Title = container != null ? container.ToString() : "null";
        }
    }
}

解决方案

The issue is that each TreeViewItem is itself an ItemsControl so they each manage their own containers for their children.

However, there's a very simple way to do what you want to do: instead of registering to the SelectedItemChanged event, register to the TreeViewItem.Selected event that will bubble up with the OriginalSource set to the selected TreeViewItem.

XAML:

<TreeView ItemsSource="{StaticResource Array}" TreeViewItem.Selected="TreeViewItem_Selected">

Code behind:

private void TreeViewItem_Selected(object sender, RoutedEventArgs e) {
    TreeViewItem container = (TreeViewItem) e.OriginalSource;
    Title = container != null ? container.ToString() : "null";
}

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