WPicView/WPicView/MainWindow.xaml.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;

namespace WPicView
{
    /// <summary>
    /// Interaction logic for MainWindow.xaml
    /// </summary>
    public partial class MainWindow : Window
    {
        string[] allFiles = null;
        string[] allDirs = null;
        int fPos = 0;
        int dPos ;
        string searchPattern = "*.png";

        ScaleTransform st = new ScaleTransform();
        TranslateTransform tt = new TranslateTransform();
        TransformGroup group = new TransformGroup();


        public MainWindow()
        {
            InitializeComponent();
            //            allFiles  = System.IO.Directory.GetFiles("C:\\Users\\U15020\\SShot\\2020-05-01");

            allDirs = System.IO.Directory.GetDirectories(System.Environment.GetEnvironmentVariable ("USERPROFILE") + "\\SShot", "202*");
            dPos = allDirs.Length - 1;
            allFiles  = System.IO.Directory.GetFiles(allDirs[dPos], searchPattern);
            fPos = allFiles.Length-1;
            showFile(allFiles[fPos]);
            group.Children.Add(st);
            group.Children.Add(tt);
            
        }
        
        private void showFile(String fileName) {
            this.Title = allFiles[fPos];
            try {
                IMG1.Source = new BitmapImage(new Uri(fileName));
            } catch (Exception ex) {
                this.Title = "ERRROR LOADING FILE " + this.Title;
            }
        }

        private void OnKeyDownHandler(object sender, KeyEventArgs e)
        {
            // Directory Navigation
            if (e.Key == System.Windows.Input.Key.Up) 
            {
                if (dPos > 0)
                {
                    dPos -= 1;
                    allFiles = System.IO.Directory.GetFiles(allDirs[dPos], searchPattern);
                    fPos = allFiles.Length -1;
                }
            }
            else if (e.Key == System.Windows.Input.Key.Down)
            {
                if (dPos < allDirs.Length - 1)
                {
                    dPos += 1;
                    allFiles = System.IO.Directory.GetFiles(allDirs[dPos], searchPattern);
                    fPos = allFiles.Length - 1;
                }
            }

            // File Navigation
            if (e.Key == System.Windows.Input.Key.Right) {
                if (fPos < allFiles.Length -1 ) {
                    fPos += 1;
                } else
                {
                    // look if more files popped up in the meantime...
                    allFiles = System.IO.Directory.GetFiles(allDirs[dPos], searchPattern);
                    if (fPos < allFiles.Length - 1)
                    {
                        fPos += 1;
                    }
                }
                
            } else if (e.Key == System.Windows.Input.Key.Left) {
                if (fPos > 0) {
                    fPos -= 1;
                }
            }

            if (e.Key == Key.End)
            {
                allFiles = System.IO.Directory.GetFiles(allDirs[dPos], searchPattern);
                fPos = allFiles.Length - 1;
            }
            if (e.Key == Key.Home )
            {
                fPos = 0;
            }

            // Display file
            if (allFiles.Length > 0)
            {
                showFile(allFiles[fPos]);
            }

            // zoom - TODO
            if (e.Key == System.Windows.Input.Key.PageUp)
            {
                //https://stackoverflow.com/questions/741956/pan-zoom-image

                IMG1.RenderTransform = group;

                st.ScaleX += 0.2;
                st.ScaleY += 0.2;

            }
            if (e.Key == System.Windows.Input.Key.PageDown)
            {
                //https://stackoverflow.com/questions/741956/pan-zoom-image

                IMG1.RenderTransform = group;

                st.ScaleX -= 0.2;
                st.ScaleY -= 0.2;

            }
            if (e.Key == System.Windows.Input.Key.L) 
            {
                IMG1.RenderTransform = group;

                tt.X -= 25; 
            }
            if (e.Key == System.Windows.Input.Key.H)
            {
                IMG1.RenderTransform = group;

                tt.X += 25;
            }
            if (e.Key == System.Windows.Input.Key.J)
            {
                IMG1.RenderTransform = group;

                tt.Y -= 25;
            }
            if (e.Key == System.Windows.Input.Key.K)
            {
                IMG1.RenderTransform = group;

                tt.Y += 25;
            }

        }
    }
}