WPF ComboBox DataTemplate Image

<ComboBox 
          ItemsSource="{StaticResource dataList}"
          SelectedIndex="0"
          VirtualizingPanel.IsContainerVirtualizable="True"
          VirtualizingPanel.IsVirtualizing="True"
          VirtualizingPanel.VirtualizationMode="Recycling">
    <ComboBox.ItemTemplate>
        <DataTemplate>
            <Image Source="{Binding SelectedItem,RelativeSource=
                {RelativeSource Mode=FindAncestor,AncestorType={x:Type ComboBox}}}"
                Stretch="Uniform"/>
        </DataTemplate>
    </ComboBox.ItemTemplate>
</ComboBox>

//xaml
<Window x:Class="WpfApp394.MainWindow"
        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"
        xmlns:local="clr-namespace:WpfApp394"
        mc:Ignorable="d" 
        WindowState="Maximized"
        Title="MainWindow">
    <Window.Resources>
        <local:DataList x:Key="dataList"/>
    </Window.Resources>
    <Grid>
        <ComboBox 
                  ItemsSource="{StaticResource dataList}"
                  SelectedIndex="0"
                  VirtualizingPanel.IsContainerVirtualizable="True"
                  VirtualizingPanel.IsVirtualizing="True"
                  VirtualizingPanel.VirtualizationMode="Recycling">
            <ComboBox.ItemTemplate>
                <DataTemplate>
                    <Image Source="{Binding SelectedItem,RelativeSource=
                        {RelativeSource Mode=FindAncestor,AncestorType={x:Type ComboBox}}}"
                        Stretch="Uniform"/>
                </DataTemplate>
            </ComboBox.ItemTemplate>
        </ComboBox>
    </Grid>
</Window>



//cs
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.Navigation;
using System.Windows.Shapes;
using System.IO;

namespace WpfApp394
{
    /// <summary>
    /// Interaction logic for MainWindow.xaml
    /// </summary>
    public partial class MainWindow : Window
    {
        public MainWindow()
        {
            InitializeComponent();
        }
    }

    public class DataList:List<string>
    {
        public DataList()
        {
            var imgsList = Directory.GetFiles(@"../../Images");
            if(imgsList!=null && imgsList.Any())
            {
                this.AddRange(imgsList);
            }
        }
    }
}