WPF ListBox show image via DataTemplate via string as image source directly

        <ListBox x:Name="lbx"
          ItemsSource="{Binding ImgsList,Mode=TwoWay,UpdateSourceTrigger=PropertyChanged}">                   
            <ListBox.ItemTemplate>
                <DataTemplate>
                    <Image Source="{Binding Path=DataContext,RelativeSource={RelativeSource 
                        Mode=FindAncestor,AncestorType={x:Type ListBoxItem}}}"
                           Width="{Binding ActualWidth,RelativeSource={RelativeSource Mode=FindAncestor,
                        AncestorType={x:Type Window}}}"
                           Height="{Binding ActualHeight,RelativeSource={RelativeSource Mode=FindAncestor,
                        AncestorType={x:Type Window}}}"/>
                </DataTemplate>
            </ListBox.ItemTemplate>
        </ListBox>

//xaml
<Window x:Class="WpfApp162.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:behavior="http://schemas.microsoft.com/xaml/behaviors"
        xmlns:local="clr-namespace:WpfApp162"
        WindowState="Maximized"
        mc:Ignorable="d"
        Height="450" Width="800">
    <Grid>
        <ListBox x:Name="lbx"
          ItemsSource="{Binding ImgsList,Mode=TwoWay,UpdateSourceTrigger=PropertyChanged}">                   
            <ListBox.ItemTemplate>
                <DataTemplate>
                    <Image Source="{Binding Path=DataContext,RelativeSource={RelativeSource 
                        Mode=FindAncestor,AncestorType={x:Type ListBoxItem}}}"
                           Width="{Binding ActualWidth,RelativeSource={RelativeSource Mode=FindAncestor,
                        AncestorType={x:Type Window}}}"
                           Height="{Binding ActualHeight,RelativeSource={RelativeSource Mode=FindAncestor,
                        AncestorType={x:Type Window}}}"/>
                </DataTemplate>
            </ListBox.ItemTemplate>
        </ListBox>
    </Grid>
</Window>


//cs
using System;
using System.Collections.Generic;
using System.ComponentModel;
using System.IO;
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;

namespace WpfApp162
{
    /// <summary>
    /// Interaction logic for MainWindow.xaml
    /// </summary>
    public partial class MainWindow : Window
    {
        private int prevIdx = -1;
        public MainWindow()
        {
            InitializeComponent();
            var vm = new MainVM();
            this.DataContext = vm;
            
        }
    }

    public class MainVM : INotifyPropertyChanged
    {
        public event PropertyChangedEventHandler PropertyChanged;
        private void OnPropertyChanged(string propName)
        {
            var handler = PropertyChanged;
            if (handler != null)
            {
                handler?.Invoke(this, new PropertyChangedEventArgs(propName));
            }
        }

        public MainVM()
        {
            InitImgsList();
        }

        private void InitImgsList()
        {
            var imgs = Directory.GetFiles(@"../../Images");
            if (imgs != null && imgs.Any())
            {
                int len = imgs.Count();
                ImgsList = new List<string>();
                for (int i = 0; i < 2000; i++)
                {
                    ImgsList.Add(imgs[i % len]);
                }
            }
        }

        private List<string> imgsList;
        public List<string> ImgsList
        {
            get
            {
                return imgsList;
            }
            set
            {
                if (value != imgsList)
                {
                    imgsList = value;
                    OnPropertyChanged(nameof(ImgsList));
                }
            }
        }
    }     
}