WPF TreeView：使用边框为每个TreeViewItem加下划线

Question

我只需要在每个TreeViewItem显示后添加一行TreeView样式，该行从左侧TreeView边框开始，到右侧TreeView边界结束;我想要获得的是：

我尝试生成样式并在主网格周围添加边框......结果很糟糕：

WPF专家可以帮助我吗？ TIA

<Window
    xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation"
    xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"
    xmlns:d="http://schemas.microsoft.com/expression/blend/2008"
    xmlns:mc="http://schemas.openxmlformats.org/markup-compatibility/2006" 
    mc:Ignorable="d" x:Class="Test04.MainWindow"
    Title="MainWindow" Height="350" Width="266">
      <Window.Resources>
        <Style x:Key="TreeViewItemFocusVisual">
          <Setter Property="Control.Template">
            <Setter.Value>
              <ControlTemplate>
                <Rectangle/>
              </ControlTemplate>
            </Setter.Value>
          </Setter>
        </Style>
        <SolidColorBrush x:Key="TreeViewItem.TreeArrow.Static.Checked.Fill" Color="#FF595959"/>
        <SolidColorBrush x:Key="TreeViewItem.TreeArrow.Static.Checked.Stroke" Color="#FF262626"/>
        <SolidColorBrush x:Key="TreeViewItem.TreeArrow.MouseOver.Stroke" Color="#FF1BBBFA"/>
        <SolidColorBrush x:Key="TreeViewItem.TreeArrow.MouseOver.Fill" Color="Transparent"/>
        <SolidColorBrush x:Key="TreeViewItem.TreeArrow.MouseOver.Checked.Stroke" Color="#FF262626"/>
        <SolidColorBrush x:Key="TreeViewItem.TreeArrow.MouseOver.Checked.Fill" Color="#FF595959"/>
        <PathGeometry x:Key="TreeArrow" Figures="M0,0 L0,6 L6,0 z"/>
        <SolidColorBrush x:Key="TreeViewItem.TreeArrow.Static.Fill" Color="Transparent"/>
        <SolidColorBrush x:Key="TreeViewItem.TreeArrow.Static.Stroke" Color="#FF989898"/>
        <Style x:Key="ExpandCollapseToggleStyle" TargetType="{x:Type ToggleButton}">
          <Setter Property="Focusable" Value="False"/>
          <Setter Property="Width" Value="16"/>
          <Setter Property="Height" Value="16"/>
          <Setter Property="Template">
            <Setter.Value>
              <ControlTemplate TargetType="{x:Type ToggleButton}">
                <Border Background="Transparent" Height="16" Padding="5,5,5,5" Width="16">
                  <Path x:Name="ExpandPath" Data="{StaticResource TreeArrow}" Fill="{StaticResource TreeViewItem.TreeArrow.Static.Fill}" Stroke="{StaticResource TreeViewItem.TreeArrow.Static.Stroke}">
                    <Path.RenderTransform>
                      <RotateTransform Angle="135" CenterY="3" CenterX="3"/>
                    </Path.RenderTransform>
                  </Path>
                </Border>
                <ControlTemplate.Triggers>
                  <Trigger Property="IsChecked" Value="True">
                    <Setter Property="RenderTransform" TargetName="ExpandPath">
                      <Setter.Value>
                        <RotateTransform Angle="180" CenterY="3" CenterX="3"/>
                      </Setter.Value>
                    </Setter>
                    <Setter Property="Fill" TargetName="ExpandPath" Value="{StaticResource TreeViewItem.TreeArrow.Static.Checked.Fill}"/>
                    <Setter Property="Stroke" TargetName="ExpandPath" Value="{StaticResource TreeViewItem.TreeArrow.Static.Checked.Stroke}"/>
                  </Trigger>
                  <Trigger Property="IsMouseOver" Value="True">
                    <Setter Property="Stroke" TargetName="ExpandPath" Value="{StaticResource TreeViewItem.TreeArrow.MouseOver.Stroke}"/>
                    <Setter Property="Fill" TargetName="ExpandPath" Value="{StaticResource TreeViewItem.TreeArrow.MouseOver.Fill}"/>
                  </Trigger>
                  <MultiTrigger>
                    <MultiTrigger.Conditions>
                      <Condition Property="IsMouseOver" Value="True"/>
                      <Condition Property="IsChecked" Value="True"/>
                    </MultiTrigger.Conditions>
                    <Setter Property="Stroke" TargetName="ExpandPath" Value="{StaticResource TreeViewItem.TreeArrow.MouseOver.Checked.Stroke}"/>
                    <Setter Property="Fill" TargetName="ExpandPath" Value="{StaticResource TreeViewItem.TreeArrow.MouseOver.Checked.Fill}"/>
                  </MultiTrigger>
                </ControlTemplate.Triggers>
              </ControlTemplate>
            </Setter.Value>
          </Setter>
        </Style>
        <Style x:Key="TreeViewItemStyle1" TargetType="{x:Type TreeViewItem}">
          <Setter Property="Background" Value="Transparent"/>
          <Setter Property="HorizontalContentAlignment" Value="{Binding HorizontalContentAlignment, RelativeSource={RelativeSource AncestorType={x:Type ItemsControl}}}"/>
          <Setter Property="VerticalContentAlignment" Value="{Binding VerticalContentAlignment, RelativeSource={RelativeSource AncestorType={x:Type ItemsControl}}}"/>
          <Setter Property="Padding" Value="1,0,0,0"/>
          <Setter Property="Foreground" Value="{DynamicResource {x:Static SystemColors.ControlTextBrushKey}}"/>
          <Setter Property="FocusVisualStyle" Value="{StaticResource TreeViewItemFocusVisual}"/>
          <Setter Property="Template">
            <Setter.Value>
              <ControlTemplate TargetType="{x:Type TreeViewItem}">
                <Border BorderThickness="0 0 0 1" BorderBrush="CadetBlue">
                  <Grid>
                    <Grid.ColumnDefinitions>
                      <ColumnDefinition MinWidth="19" Width="Auto"/>
                      <ColumnDefinition Width="Auto"/>
                      <ColumnDefinition Width="*"/>
                    </Grid.ColumnDefinitions>
                    <Grid.RowDefinitions>
                      <RowDefinition Height="Auto"/>
                      <RowDefinition/>
                    </Grid.RowDefinitions>
                    <ToggleButton x:Name="Expander" ClickMode="Press" IsChecked="{Binding IsExpanded, RelativeSource={RelativeSource TemplatedParent}}" Style="{StaticResource ExpandCollapseToggleStyle}"/>
                    <Border x:Name="Bd" BorderBrush="{TemplateBinding BorderBrush}" BorderThickness="{TemplateBinding BorderThickness}" Background="{TemplateBinding Background}" Grid.Column="1" Padding="{TemplateBinding Padding}" SnapsToDevicePixels="true">
                      <ContentPresenter x:Name="PART_Header" ContentSource="Header" HorizontalAlignment="{TemplateBinding HorizontalContentAlignment}" SnapsToDevicePixels="{TemplateBinding SnapsToDevicePixels}"/>
                    </Border>
                    <ItemsPresenter x:Name="ItemsHost" Grid.ColumnSpan="2" Grid.Column="1" Grid.Row="1"/>
                  </Grid>
                </Border>
                <ControlTemplate.Triggers>
                  <Trigger Property="IsExpanded" Value="false">
                    <Setter Property="Visibility" TargetName="ItemsHost" Value="Collapsed"/>
                  </Trigger>
                  <Trigger Property="HasItems" Value="false">
                    <Setter Property="Visibility" TargetName="Expander" Value="Hidden"/>
                  </Trigger>
                  <Trigger Property="IsSelected" Value="true">
                    <Setter Property="Background" TargetName="Bd" Value="{DynamicResource {x:Static SystemColors.HighlightBrushKey}}"/>
                    <Setter Property="Foreground" Value="{DynamicResource {x:Static SystemColors.HighlightTextBrushKey}}"/>
                  </Trigger>
                  <MultiTrigger>
                    <MultiTrigger.Conditions>
                      <Condition Property="IsSelected" Value="true"/>
                      <Condition Property="IsSelectionActive" Value="false"/>
                    </MultiTrigger.Conditions>
                    <Setter Property="Background" TargetName="Bd" Value="{DynamicResource {x:Static SystemColors.InactiveSelectionHighlightBrushKey}}"/>
                    <Setter Property="Foreground" Value="{DynamicResource {x:Static SystemColors.InactiveSelectionHighlightTextBrushKey}}"/>
                  </MultiTrigger>
                  <Trigger Property="IsEnabled" Value="false">
                    <Setter Property="Foreground" Value="{DynamicResource {x:Static SystemColors.GrayTextBrushKey}}"/>
                  </Trigger>
                </ControlTemplate.Triggers>
              </ControlTemplate>
            </Setter.Value>
          </Setter>
          <Style.Triggers>
            <Trigger Property="VirtualizingPanel.IsVirtualizing" Value="true">
              <Setter Property="ItemsPanel">
                <Setter.Value>
                  <ItemsPanelTemplate>
                    <VirtualizingStackPanel/>
                  </ItemsPanelTemplate>
                </Setter.Value>
              </Setter>
            </Trigger>
          </Style.Triggers>
        </Style>
      </Window.Resources>
      <Grid>
        <TreeView x:Name="tv" Margin="5">
          <TreeView.Resources>
            <Style TargetType="{x:Type TreeViewItem}" BasedOn="{StaticResource TreeViewItemStyle1}"/>
          </TreeView.Resources>
          <TreeViewItem Header="01">
            <TreeViewItem Header="01-01"/>
            <TreeViewItem Header="01-02"/>
          </TreeViewItem>
          <TreeViewItem Header="02">
            <TreeViewItem Header="02-01"/>
            <TreeViewItem Header="02-02"/>
          </TreeViewItem>
          <TreeViewItem Header="03">
            <TreeViewItem Header="03-01">
              <TreeViewItem Header="03-01-01"/>
              <TreeViewItem Header="03-01-02"/>
              <TreeViewItem Header="03-01-03"/>
            </TreeViewItem>
            <TreeViewItem Header="04-01"/>
          </TreeViewItem>
        </TreeView>


      </Grid>
    </Window>