从DataTemplate设置父ContentPresenter的附加属性

<!-- 定义附加属性 -->
public static class CustomProperties
{
    public static readonly DependencyProperty CustomAttachedPropertyProperty =
        DependencyProperty.RegisterAttached(
            "CustomAttachedProperty",
            typeof(string),
            typeof(CustomProperties),
            new PropertyMetadata(string.Empty));

    public static string GetCustomAttachedProperty(DependencyObject obj)
    {
        return (string)obj.GetValue(CustomAttachedPropertyProperty);
    }

    public static void SetCustomAttachedProperty(DependencyObject obj, string value)
    {
        obj.SetValue(CustomAttachedPropertyProperty, value);
    }
}

<!-- 在XAML中使用 -->
<Window x:Class="YourNamespace.MainWindow"
        xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation"
        xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"
        xmlns:local="clr-namespace:YourNamespace"
        Title="MainWindow" Height="450" Width="800">
    <Window.Resources>
        <DataTemplate x:Key="YourDataTemplate">
            <TextBlock Text="{Binding YourProperty}">
                <!-- 使用RelativeSource定位父ContentPresenter并设置附加属性 -->
                <TextBlock.Style>
                    <Style TargetType="TextBlock">
                        <Setter Property="local:CustomProperties.CustomAttachedProperty" 
                                Value="YourValue" />
                    </Style>
                </TextBlock.Style>
            </TextBlock>
        </DataTemplate>
    </Window.Resources>
    <Grid>
        <ContentPresenter ContentTemplate="{StaticResource YourDataTemplate}" 
                          Content="{Binding YourDataObject}" />
    </Grid>
</Window>