现在您必须双击或单击 + 图标。 有没有办法使用户单击节点的任何位置即可展开?
我曾遇到这个问题,通过另一个StackOverflow帖子找到了一个好的解决方案。
在control.xaml的TreeView元素中,你可以直接连接到TreeViewItem的Selected事件:
<TreeView ItemsSource="{StaticResource Array}" TreeViewItem.Selected="TreeViewItem_Selected"/>
然后在您的control.xaml.cs代码中,您可以从RoutedEventArgs中获取选择的TreeViewItem,并将其设置为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;
}
很好,干净利落。希望这对某人有所帮助!
static DependencyObject VisualUpwardSearch<T>(DependencyObject source)
{
while (source != null && source.GetType() != typeof(T))
source = VisualTreeHelper.GetParent(source);
return source;
}
然后在TreeViewItem.Selected处理程序中:
private void Treeview_Selected(object sender, RoutedEventArgs e)
{
var treeViewItem = VisualUpwardSearch<TreeViewItem>(e.OriginalSource as DependencyObject) as TreeViewItem;
if (treeViewItem != null) treeViewItem.IsExpanded = true;
}
VisualUpwardSearch的魔法来自于这里:在显示上下文菜单之前,选择TreeView节点
敬礼
<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>
重要的部分是在ControlTemplate中定义复选框并进行绑定。当复选框被选中时,只需单击一次即可展开该项。
<CheckBox Style="{StaticResource TreeViewItemCB}" IsChecked="{Binding Path=IsExpanded,Mode=OneWayToSource,RelativeSource={RelativeSource TemplatedParent}}" ClickMode="Press">
这个样式是为了让复选框可以被拉伸,且不会显示边框。
<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>
@BJennings提供了很好的答案。然而,如果你想展开或收缩一个已经选定的项,它不起作用。为了改进这个问题,你可以简单地添加:tvi.IsSelected = false;(如果你不关心该项是否处于选定状态。)
所以,整个代码看起来像这样:
private void TreeViewItem_Selected(object sender, RoutedEventArgs e)
{
TreeViewItem tvi = e.OriginalSource as TreeViewItem;
if (tvi == null || e.Handled) return;
tvi.IsExpanded = !tvi.IsExpanded;
tvi.IsSelected = false;
e.Handled = true;
}
另一种方法是使用附加属性。
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;
}
}
<TreeView controls:VirtualOneClickExpandButtonBehavior.Enabled="true" ItemsSource="{Binding HierarchicalModel}"/>
被接受的解决方案在使用键盘导航时有奇怪的行为,并且在已经选择该项时不会折叠该项。或者,只需从TreeViewItem派生一个新类并覆盖MouseLeftButtonDown方法。您还需要将TreeView.ItemsSource设置为新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);
}
<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);
}
这是答案,希望您喜欢
回答者:阿里·拉希米
if (!e.Handled) {...}
中,并在切换IsExpanded
属性后立即设置e.Handled = true;
。 - kroimon