C# 树视图项目已选定，鼠标按钮按下事件未触发

我已经为树状视图创建了视图模型。还创建了它们的绑定。我创建了样式触发器，这样每当选择树视图项时，它的背景都会改变。但是背景没有改变。我处理了选中的项目和树视图项目的鼠标左键按下事件，以查看该项目是否被选中。但这两个事件都没有发生。下面是XAML

<TreeView Grid.Row="0" x:Name="TreeViewLocalSystem"  BorderBrush="Transparent" Panel.ZIndex="0">
     <TreeView.ItemContainerStyle>
        <Style TargetType="TreeViewItem">
            <Setter Property="IsExpanded" Value="{Binding IsExpanded, Mode=TwoWay}" />
            <Setter Property="IsSelected" Value="{Binding IsSelected, Mode=TwoWay}" />
            <Style.Triggers>
                <Trigger Property="IsSelected" Value="True">
                    <Setter Property="Background" Value="{StaticResource TextBoxBackgroundColor}"></Setter>
                </Trigger>
                <Trigger Property="IsSelected" Value="False">
                    <Setter Property="Background" Value="Transparent"></Setter>
                </Trigger>
            </Style.Triggers>
        </Style>
    </TreeView.ItemContainerStyle>
    <TreeView.Resources>
        <HierarchicalDataTemplate ItemsSource="{Binding Path=Children}"   DataType="{x:Type local:LocalTreeViewItemModel}">
            <TreeViewItem Header="{Binding Path=Text}"  Selected="TreeViewItem_Selected" HorizontalAlignment="Left" FontSize="{StaticResource MediumFontSize}" MouseLeftButtonDown="TreeViewItem_MouseLeftButtonDown" />
        </HierarchicalDataTemplate>
    </TreeView.Resources>
</TreeView>

我做错了什么

编辑：我注意到的另一件事是，当我右键单击时会触发MouseDown事件，但在鼠标左键单击时不会触发。

您可以为TreeView项目处理PreviewMouseLeftButtonDown事件：

<TreeView Grid.Row="0" x:Name="TreeViewLocalSystem"  BorderBrush="Transparent" Panel.ZIndex="0">
    <TreeView.ItemContainerStyle>
        <Style TargetType="TreeViewItem">
            <EventSetter Event="PreviewMouseLeftButtonDown" Handler="TreeViewLocalSystem_PreviewMouseLeftButtonDown" />
            <Setter Property="IsExpanded" Value="{Binding IsExpanded, Mode=TwoWay}" />
            <Setter Property="IsSelected" Value="{Binding IsSelected, Mode=TwoWay}" />
            <Style.Triggers>
                <Trigger Property="IsSelected" Value="True">
                    <Setter Property="Background" Value="{StaticResource TextBoxBackgroundColor}"></Setter>
                </Trigger>
                <Trigger Property="IsSelected" Value="False">
                    <Setter Property="Background" Value="Transparent"></Setter>
                </Trigger>
            </Style.Triggers>
        </Style>
    </TreeView.ItemContainerStyle>
    <TreeView.Resources>
        <HierarchicalDataTemplate ItemsSource="{Binding Path=Children}" DataType="{x:Type local:LocalTreeViewItemModel}">
            <TextBlock Text="{Binding Path=Text}" HorizontalAlignment="Left" FontSize="{StaticResource MediumFontSize}" />
        </HierarchicalDataTemplate>
    </TreeView.Resources>
</TreeView>

private void TreeViewLocalSystem_PreviewMouseLeftButtonDown(object sender, MouseButtonEventArgs e)
{
    //...
}