WPF render image, scaletransfrom and translatertransform

<Window x:Class="WpfApp392.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:WpfApp392"
        mc:Ignorable="d"     
        WindowState="Maximized"
        KeyDown="Window_KeyDown"
        MouseDown="img_MouseDown"
        MouseMove="img_MouseMove"
        MouseUp="img_MouseUp"
        Title="MainWindow" Height="450" Width="800">
    <Grid>
        <Image x:Name="img" ClipToBounds="True"
               Source="{Binding ImgUrl,Mode=TwoWay,UpdateSourceTrigger=PropertyChanged}"
               RenderOptions.BitmapScalingMode="HighQuality" 
               MouseWheel="Image_MouseWheel">
            <Image.RenderTransform>
                <TransformGroup>
                    <ScaleTransform x:Name="scaler"/>
                    <TranslateTransform x:Name="translater"/>
                </TransformGroup>
            </Image.RenderTransform>
        </Image>
    </Grid>
</Window>


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 WpfApp392
{
    /// <summary>
    /// Interaction logic for MainWindow.xaml
    /// </summary>
    public partial class MainWindow : Window, INotifyPropertyChanged
    {
        private List<string> imgsList { get; set; }
        private int imgsCount { get; set; }
        private int imgIndex { get; set; }
        private Point currentPt { get; set; }

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

        public MainWindow()
        {
            InitializeComponent();
            this.Loaded += MainWindow_Loaded;
            this.DataContext=this;
        }

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

        private void MainWindow_Loaded(object sender, RoutedEventArgs e)
        {
            imgsList = Directory.GetFiles(@"../../Images")?.ToList();
            if (imgsList != null && imgsList.Any())
            {
                imgsCount = imgsList.Count();
                imgIndex = 0;
                ImgUrl = imgsList[imgIndex];
            }
        }

        private void Window_KeyDown(object sender, KeyEventArgs e)
        {
            if (e.Key == Key.Up)
            {
                if (--imgIndex < 0)
                {
                    imgIndex = imgsCount - 1;
                }
            }
            else if (e.Key==Key.Down)
            {
                if (++imgIndex>=imgsCount)
                {
                    imgIndex = 0;
                }
            }
            this.Title = imgIndex.ToString();
            ImgUrl = imgsList[imgIndex];
            scaler.ScaleX = 1;
            scaler.ScaleY = 1;
            scaler.CenterX = 0;
            scaler.CenterY = 0;
            translater.X = 0;
            translater.Y = 0;
        }

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

        private void img_MouseDown(object sender, MouseButtonEventArgs e)
        {
            currentPt = e.GetPosition(this);
        }

        private void img_MouseMove(object sender, MouseEventArgs e)
        {
            isMoving = true;
        }

        private void img_MouseUp(object sender, MouseButtonEventArgs e)
        {
            if(e.ChangedButton==MouseButton.Left && e.ButtonState==MouseButtonState.Released && isMoving)
            {
                var pt = e.GetPosition(this);
                translater.X += (pt.X - currentPt.X);
                translater.Y += (pt.Y - currentPt.Y);
                isMoving = false;
            }
        }
    }
}