WPF RelativeSource的使用

<Window x:Class="XamlTest.Window15"
        xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation"
        xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"
        Title="Window15" Height="300" Width="300">
    <Grid>
        <StackPanel Name="sp1">
            <Grid Name="gd1">
                <StackPanel Name="sp2">
                    <Grid Name="gd2">
                        <!--<TextBlock Text="{Binding RelativeSource={RelativeSource AncestorLevel=1, AncestorType=StackPanel, Mode=FindAncestor}, Path=Name}"></TextBlock>-->//xaml实现
                        <TextBlock Name="txt"></TextBlock>
                    </Grid>
                </StackPanel>
            </Grid>
        </StackPanel>
    </Grid>

</Window>

using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;
using System.Threading.Tasks;
using System.Windows;
using System.Windows.Controls;
using System.Windows.Data;
using System.Windows.Documents;
using System.Windows.Input;
using System.Windows.Media;
using System.Windows.Media.Imaging;
using System.Windows.Shapes;

namespace XamlTest
{
    /// <summary>
    /// Interaction logic for Window15.xaml
    /// </summary>
    public partial class Window15 : Window
    {
        public Window15()
        {
            InitializeComponent();
            Binding b = new Binding();
            b.RelativeSource = new RelativeSource(RelativeSourceMode.FindAncestor, typeof(StackPanel), 1);
            b.Path = new PropertyPath("Name");
            txt.SetBinding(TextBlock.TextProperty, b);
        }
    }
}