<ItemsControl x:Class="HDSProject.Control.CustomFont" xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation" xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml" xmlns:mc="http://schemas.openxmlformats.org/markup-compatibility/2006" xmlns:d="http://schemas.microsoft.com/expression/blend/2008" xmlns:local="clr-namespace:HDSProject.Control" mc:Ignorable="d" d:DesignHeight="450" d:DesignWidth="800" x:Name="itemCtrl" ItemsSource="{Binding Path=Title2, RelativeSource={RelativeSource Mode=Self}}" FontSize="20" Foreground="Teal" > <ItemsControl.ItemContainerStyle> <Style TargetType="ContentPresenter"> <Setter Property="VerticalAlignment" Value="Center" /> </Style> </ItemsControl.ItemContainerStyle> <ItemsControl.ItemsPanel> <ItemsPanelTemplate> <StackPanel Orientation="Horizontal" HorizontalAlignment="Center"/> </ItemsPanelTemplate> </ItemsControl.ItemsPanel> <ItemsControl.ItemTemplate> <DataTemplate> <StackPanel> <Border Margin="{Binding Path=CharacterSpacing, RelativeSource={RelativeSource Mode=FindAncestor, AncestorType=local:CustomFont}}"> <TextBlock Text="{Binding}" /> </Border> <Rectangle Height="1" Fill="{Binding Foreground, ElementName=itemCtrl}" Margin="0,0,0,5"> <Rectangle.Style> <Style TargetType="Rectangle"> <Setter Property="Visibility" Value="Collapsed" /> <Style.Triggers> <DataTrigger Binding="{Binding ShowUnderline, RelativeSource={RelativeSource Mode=FindAncestor, AncestorType=local:CustomFont}}" Value="True"> <Setter Property="Visibility" Value="Visible" /> </DataTrigger> </Style.Triggers> </Style> </Rectangle.Style> </Rectangle> </StackPanel> </DataTemplate> </ItemsControl.ItemTemplate> </ItemsControl>给这个自定义控件添加Thumb

要为这个自定义控件添加Thumb，可以使用以下步骤：

1. 在ItemsControl的外部包裹一个Grid，并添加一个Thumb控件。
2. 将ItemsControl的HorizontalAlignment和VerticalAlignment属性设置为Stretch。
3. 将Thumb控件的HorizontalAlignment和VerticalAlignment属性设置为Bottom和Right。
4. 给Thumb控件添加拖动事件处理程序，以实现控件的大小调整。

下面是示例代码：

<Grid>
  <ItemsControl x:Name="itemCtrl" ItemsSource="{Binding Path=Title2, RelativeSource={RelativeSource Mode=Self}}" FontSize="20" Foreground="Teal" HorizontalAlignment="Stretch" VerticalAlignment="Stretch">
    <ItemsControl.ItemContainerStyle>
      <Style TargetType="ContentPresenter">
        <Setter Property="VerticalAlignment" Value="Center" />
      </Style>
    </ItemsControl.ItemContainerStyle>
    <ItemsControl.ItemsPanel>
      <ItemsPanelTemplate>
        <StackPanel Orientation="Horizontal" HorizontalAlignment="Center"/>
      </ItemsPanelTemplate>
    </ItemsControl.ItemsPanel>
    <ItemsControl.ItemTemplate>
      <DataTemplate>
        <StackPanel>
          <Border Margin="{Binding Path=CharacterSpacing, RelativeSource={RelativeSource Mode=FindAncestor, AncestorType=local:CustomFont}}">
            <TextBlock Text="{Binding}" />
          </Border>
          <Rectangle Height="1" Fill="{Binding Foreground, ElementName=itemCtrl}" Margin="0,0,0,5">
            <Rectangle.Style>
              <Style TargetType="Rectangle">
                <Setter Property="Visibility" Value="Collapsed" />
                <Style.Triggers>
                  <DataTrigger Binding="{Binding ShowUnderline, RelativeSource={RelativeSource Mode=FindAncestor, AncestorType=local:CustomFont}}" Value="True">
                    <Setter Property="Visibility" Value="Visible" />
                  </DataTrigger>
                </Style.Triggers>
              </Style>
            </Rectangle.Style>
          </Rectangle>
        </StackPanel>
      </DataTemplate>
    </ItemsControl.ItemTemplate>
  </ItemsControl>
  <Thumb HorizontalAlignment="Right" VerticalAlignment="Bottom" DragDelta="Thumb_DragDelta" Width="20" Height="20" Background="Transparent"/>
</Grid>

在代码中，我们添加了一个Grid，并将ItemsControl和Thumb控件放在其中。我们将ItemsControl的HorizontalAlignment和VerticalAlignment属性设置为Stretch，以使其充满整个Grid，然后将Thumb控件的HorizontalAlignment和VerticalAlignment属性设置为Bottom和Right，使其位于ItemsControl的右下角。最后，我们为Thumb控件添加了DragDelta事件处理程序，以实现控件的大小调整。