WPF RenderTransform TransformGroup ScaleTransform TranslateTransform

<Window x:Class="WpfApp132.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:WpfApp132"
        mc:Ignorable="d"  
        WindowState="Maximized"
        MouseDown="Window_MouseDown" 
        MouseMove="Window_MouseMove"
        MouseWheel="Window_MouseWheel" 
        MouseUp="Window_MouseUp"
        Title="MainWindow" Height="450" Width="800">
    <Grid>
        <Grid.ColumnDefinitions>
            <ColumnDefinition Width="200"/>
            <ColumnDefinition />
        </Grid.ColumnDefinitions>
        <ListBox x:Name="lbx"  Grid.Column="0" 
                 ItemsSource="{Binding ImgsList,Mode=TwoWay,UpdateSourceTrigger=PropertyChanged}"
                 SelectionChanged="lbx_SelectionChanged">
            <ListBox.ItemTemplate>
                <DataTemplate>
                    <Image Source="{Binding Content,RelativeSource={RelativeSource AncestorType=ListBoxItem}}" 
                           Width="200" Height="500" />
                </DataTemplate>
            </ListBox.ItemTemplate>
        </ListBox> 
        <ContentControl Grid.Column="1" ClipToBounds="True">
            <Viewbox x:Name="viewBox" 
                     HorizontalAlignment="Stretch"
                     VerticalAlignment="Stretch" >
                <Image x:Name="img" Source="{Binding SelectedItem,ElementName=lbx}" 
                       HorizontalAlignment="Stretch" VerticalAlignment="Stretch">
                    <Image.RenderTransform>
                        <TransformGroup>
                            <ScaleTransform x:Name="scaler"/>
                            <TranslateTransform x:Name="translater"/>
                        </TransformGroup>
                    </Image.RenderTransform>
                </Image>
            </Viewbox>
        </ContentControl>      
    </Grid>
</Window>


//.cs
using System;
using System.Collections.Generic;
using System.Collections.ObjectModel;
using System.ComponentModel;
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 WpfApp132
{
    /// <summary>
    /// Interaction logic for MainWindow.xaml
    /// </summary>
    public partial class MainWindow : Window, INotifyPropertyChanged
    {
        public MainWindow()
        {
            InitializeComponent();
            InitImgsList();
            this.DataContext = this;
        }

        private void InitImgsList()
        {
            string fullDir = System.IO.Path.GetFullPath(@"..\..\Images");
            if (Directory.Exists(fullDir))
            {
                var files = System.IO.Directory.GetFiles(fullDir, "*", System.IO.SearchOption.AllDirectories);
                ImgsList = new ObservableCollection<string>(files);
                lbx.SelectedIndex = 0;
            }
        }

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

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

        private bool isMoving = false;
        public bool IsMoving
        {
            get
            {
                return isMoving;
            }
            set
            {
                if (value != isMoving)
                {
                    isMoving = value;
                    OnPropertyChanged(nameof(IsMoving));
                }
            }
        }
         

        Point previousPoint;
        private void Window_MouseDown(object sender, MouseButtonEventArgs e)
        {
            previousPoint = e.GetPosition(this);
        }

        private void Window_MouseMove(object sender, MouseEventArgs e)
        {
            IsMoving = true;
        }

        private void Window_MouseWheel(object sender, MouseWheelEventArgs e)
        {
            Point pt = e.GetPosition(this);
            if (e.Delta > 0)
            {
                scaler.ScaleX *= 1.2;
                scaler.ScaleY *= 1.2;
            }
            else
            {
                scaler.ScaleX /= 1.2;
                scaler.ScaleY /= 1.2;
            }
            scaler.CenterX = pt.X;
            scaler.CenterY = pt.Y;
        }

        private void Window_MouseUp(object sender, MouseButtonEventArgs e)
        {
            if (IsMoving && e.ButtonState == MouseButtonState.Released && e.ChangedButton == MouseButton.Left)
            {
                Point newPoint = e.GetPosition(this);
                double deltaX = newPoint.X - previousPoint.X;
                double deltaY = newPoint.Y - previousPoint.Y;
                translater.X = deltaX;
                translater.Y = deltaY;
            }
        }

        private void lbx_SelectionChanged(object sender, SelectionChangedEventArgs e)
        {
            scaler.ScaleX = 1.0;
            scaler.ScaleY = 1.0;
            img.HorizontalAlignment= HorizontalAlignment.Stretch;
            img.VerticalAlignment= VerticalAlignment.Stretch;
        }
    }
}