如何在单击项目上单击展开WPF TreeView

Question

现在，您必须双击或单击+图标。如果用户点击扩展的节点上的任何位置，是否有任何方法可以实现这一点？

Answer 1

也许不是最完美的解决方案，但这个工程：

static DependencyObject VisualUpwardSearch<T>(DependencyObject source) 
    { 
     while (source != null && source.GetType() != typeof(T)) 
      source = VisualTreeHelper.GetParent(source); 

     return source; 
    } 

然后在TreeViewItem.Selected处理程序：

 private void Treeview_Selected(object sender, RoutedEventArgs e) 
     { 
      var treeViewItem = VisualUpwardSearch<TreeViewItem>(e.OriginalSource as DependencyObject) as TreeViewItem; 
      if (treeViewItem != null) treeViewItem.IsExpanded = true; 
     } 

的VisualUpwardSearch魔术就是从这里取：Select TreeView Node on right click before displaying ContextMenu

问候

Answer 2

我有这个相同的问题和f由于another StackOverflow post，我们找到了一个很好的解决方案。

在control.xaml的TreeView的元素，你可以直接挂接到TreeViewItem的Selected事件：

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

然后在你的control.xaml.cs后面的代码，你可以从RoutedEventArgs抢选定树型视图和将其设置为IsExpanded：

private void TreeViewItem_Selected(object sender, RoutedEventArgs e) 
{ 
    TreeViewItem tvi = e.OriginalSource as TreeViewItem; 

    if (tvi == null || e.Handled) return; 

    tvi.IsExpanded = !tvi.IsExpanded; 
    e.Handled = true; 
} 

干净整洁。希望能帮助别人！

Answer 3

当您使用键盘进行导航时，接受的解决方案具有奇怪的行为，并且当它已被选中时不会折叠该项目。或者，只需从TreeViewItem派生一个新类并重写MouseLeftButtonDown方法。您还需要将您的TreeView.ItemsSource设置为您的新TreeViewItem类的集合。

protected override void OnMouseLeftButtonDown(System.Windows.Input.MouseButtonEventArgs e) 
{ 
    if (!e.Handled && base.IsEnabled) 
    { 
     this.IsExpanded = !this.IsExpanded; 
     e.Handled = true; 
    } 
    base.OnMouseLeftButtonDown(e); 
} 

Answer 4

我有同样的问题，我用Style的功能，所以你不需要处理事件。

我定义了一个样式为树型视图

<Style x:Key="{x:Type TreeViewItem}" TargetType="{x:Type TreeViewItem}"> 
    <!--<Setter Property="FocusVisualStyle" Value="{StaticResource TreeViewItemFocusVisual}"/>--> 
    <Setter Property="Template"> 
     <Setter.Value> 
      <ControlTemplate TargetType="{x:Type TreeViewItem}"> 
         <CheckBox Style="{StaticResource TreeViewItemCB}" IsChecked="{Binding Path=IsExpanded,Mode=OneWayToSource,RelativeSource={RelativeSource TemplatedParent}}" ClickMode="Press"> 
          <Grid Background="{StaticResource TreeViewItemBackground}" Margin="0"> 
          <Grid.RowDefinitions> 
           <RowDefinition Height="Auto"/> 
           <RowDefinition/> 
          </Grid.RowDefinitions> 
          <Border Name="Bd"> 
            <ContentPresenter x:Name="PART_Header" ContentSource="Header"/> 
          </Border> 
          <ItemsPresenter x:Name="ItemsHost" Grid.Row="1"/> 
          </Grid> 
         </CheckBox> 
      </ControlTemplate> 
     </Setter.Value> 
    </Setter> 
</Style> 

的重要组成部分，是定义在ControlTemplate中的复选框，并与之结合。选中CheckBox后，只需单击一次即可展开该项目。

<CheckBox Style="{StaticResource TreeViewItemCB}" IsChecked="{Binding Path=IsExpanded,Mode=OneWayToSource,RelativeSource={RelativeSource TemplatedParent}}" ClickMode="Press"> 

这是checkBox的样式，因此它可以延伸并且不会显示带有笔触的框。

<Style x:Key="TreeViewItemCB" TargetType="CheckBox" BasedOn="{StaticResource baseStyle}"> 
    <Setter Property="SnapsToDevicePixels" Value="true"/> 
    <Setter Property="OverridesDefaultStyle" Value="true"/> 
    <Setter Property="KeyboardNavigation.TabNavigation" Value="None" /> 
    <Setter Property="Background" Value="Transparent"/> 
    <Setter Property="VerticalAlignment" Value="Stretch"/> 
    <Setter Property="HorizontalAlignment" Value="Stretch"/> 
    <Setter Property="Template"> 
     <Setter.Value> 
      <ControlTemplate TargetType="CheckBox"> 
       <ContentPresenter VerticalAlignment="Stretch" HorizontalAlignment="Stretch" RecognizesAccessKey="True"/> 
      </ControlTemplate> 
     </Setter.Value> 
    </Setter> 
</Style> 

Answer 5

<TreeView.ItemContainerStyle> 
    <Style TargetType="{x:Type TreeViewItem}"> 
    <Setter Property="Cursor" Value="Hand" /> 
    <EventSetter Event="MouseUp" Handler="TreeViewItem_Click"/> 
    </Style> 
</TreeView.ItemContainerStyle> 


private void TreeViewItem_Click(object sender, MouseButtonEventArgs e) 
     { 
      ((TreeViewItem) sender).IsExpanded = !((TreeViewItem) sender).IsExpanded; 
      Thread.Sleep(700); 
     } 

这里是答案，享受它

答：阿里Rahimy

Answer 6

另一种计算策略是使用附加propperties。

public class VirtualOneClickExpandButtonBehavior : DependencyObject 
{ 
    public static bool GetEnabled(DependencyObject obj) 
    { 
     return (bool)obj.GetValue(EnabledProperty); 
    } 

    public static void SetEnabled(DependencyObject obj, bool value) 
    { 
     obj.SetValue(EnabledProperty, value); 
    } 


    public static readonly DependencyProperty EnabledProperty = 
     DependencyProperty.RegisterAttached("Enabled", typeof(bool), typeof(VirtualOneClickExpandButtonBehavior), 
      new UIPropertyMetadata(false, EnabledPropertyChangedCallback 
       )); 

    private static void EnabledPropertyChangedCallback(DependencyObject dependencyObject, DependencyPropertyChangedEventArgs dependencyPropertyChangedEventArgs) 
    { 
     var treeView = dependencyObject as TreeView; 

     if (treeView == null) return; 

     treeView.MouseUp += TreeView_MouseUp; 
    } 

    private static void TreeView_MouseUp(object sender, System.Windows.Input.MouseButtonEventArgs e) 
    { 
     var treeViewItem = VisualUpwardSearch<TreeViewItem>(e.OriginalSource as DependencyObject) as TreeViewItem; 
     if (treeViewItem != null) treeViewItem.IsExpanded = !treeViewItem.IsExpanded; 
    } 

    static DependencyObject VisualUpwardSearch<T>(DependencyObject source) 
    { 
     while (source != null && source.GetType() != typeof(T)) 
      source = VisualTreeHelper.GetParent(source); 

     return source; 
    } 
} 

然后你可以像这样使用它。

<TreeView controls:VirtualOneClickExpandButtonBehavior.Enabled="true" ItemsSource="{Binding HierarchicalModel}"/> 

如果您使用MVVM模式，因为您不需要隐藏代码，这是一个不错的选择。

而且他对Markust的VisualUpwardSearch（DependencyObject源）