Try replacing WPF with SkiaSharp

Author: t1m0thyj

src/COM/DesktopWallpaper.cs

@@ -16,6 +16,15 @@ public struct COLORREF
         public byte B;
     }
 
+    [StructLayout(LayoutKind.Sequential)]
+    public struct RECT
+    {
+        public int Left;
+        public int Top;
+        public int Right;
+        public int Bottom;
+    }
+
     public enum DesktopSlideshowOptions
     {
         DSO_SHUFFLEIMAGES = 0x01,
@@ -59,7 +68,7 @@ public interface IDesktopWallpaper
 
         uint GetMonitorDevicePathCount();
 
-        System.Windows.Rect GetMonitorRECT([MarshalAs(UnmanagedType.LPWStr)] string monitorID);
+        RECT GetMonitorRECT([MarshalAs(UnmanagedType.LPWStr)] string monitorID);
 
         void SetBackgroundColor([MarshalAs(UnmanagedType.U4)] COLORREF color);
 

src/SkiaSharp/BitmapCache.cs

@@ -0,0 +1,155 @@
+// This Source Code Form is subject to the terms of the Mozilla Public
+// License, v. 2.0. If a copy of the MPL was not distributed with this
+// file, You can obtain one at http://mozilla.org/MPL/2.0/.
+
+using System;
+using System.Collections.Generic;
+using System.IO;
+using System.Linq;
+using System.Reflection;
+using System.Windows.Forms;
+using SkiaSharp;
+
+namespace WinDynamicDesktop.SkiaSharp
+{
+    sealed class BitmapCache
+    {
+        readonly int maxWidth;
+        readonly int maxHeight;
+        readonly object cacheLock = new object();
+        readonly Dictionary<Uri, SKBitmap> images = new Dictionary<Uri, SKBitmap>();
+
+        public SKBitmap this[Uri uri]
+        {
+            get
+            {
+                lock (cacheLock)
+                {
+                    if (images.ContainsKey(uri))
+                    {
+                        return images[uri];
+                    }
+                    else
+                    {
+                        var img = CreateImage(uri);
+                        if (img != null)
+                        {
+                            images.Add(uri, img);
+                        }
+                        return img;
+                    }
+                }
+            }
+        }
+
+        public void Clear()
+        {
+            lock (cacheLock)
+            {
+                foreach (var bitmap in images.Values)
+                {
+                    bitmap?.Dispose();
+                }
+                images.Clear();
+            }
+            GC.Collect();
+        }
+
+        public BitmapCache(bool limitDecodeSize = true)
+        {
+            if (limitDecodeSize)
+            {
+                int maxArea = 0;
+                foreach (Screen screen in Screen.AllScreens)
+                {
+                    int area = screen.Bounds.Width * screen.Bounds.Height;
+                    if (area > maxArea)
+                    {
+                        maxArea = area;
+                        maxWidth = screen.Bounds.Width;
+                        maxHeight = screen.Bounds.Height;
+                    }
+                }
+            }
+            else
+            {
+                maxWidth = int.MaxValue;
+                maxHeight = int.MaxValue;
+            }
+        }
+
+        private SKBitmap CreateImage(Uri uri)
+        {
+            try
+            {
+                Stream stream = null;
+
+                if (uri.IsAbsoluteUri && uri.Scheme == "file")
+                {
+                    string path = uri.LocalPath;
+                    if (File.Exists(path))
+                    {
+                        stream = File.OpenRead(path);
+                    }
+                }
+                else if (!uri.IsAbsoluteUri)
+                {
+                    // Embedded resource
+                    stream = Assembly.GetExecutingAssembly().GetManifestResourceStream(uri.OriginalString);
+                }
+
+                if (stream == null)
+                {
+                    return null;
+                }
+
+                using (stream)
+                {
+                    using (var codec = SKCodec.Create(stream))
+                    {
+                        if (codec == null)
+                        {
+                            return null;
+                        }
+
+                        var info = codec.Info;
+                        
+                        // Calculate scaled dimensions
+                        int targetWidth = info.Width;
+                        int targetHeight = info.Height;
+
+                        if (info.Width > maxWidth || info.Height > maxHeight)
+                        {
+                            float scale = Math.Min((float)maxWidth / info.Width, (float)maxHeight / info.Height);
+                            targetWidth = (int)(info.Width * scale);
+                            targetHeight = (int)(info.Height * scale);
+                        }
+
+                        var bitmap = new SKBitmap(targetWidth, targetHeight, info.ColorType, info.AlphaType);
+                        
+                        if (targetWidth == info.Width && targetHeight == info.Height)
+                        {
+                            // No scaling needed
+                            codec.GetPixels(bitmap.Info, bitmap.GetPixels());
+                        }
+                        else
+                        {
+                            // Decode at full size then scale down with high quality
+                            using (var fullBitmap = new SKBitmap(info))
+                            {
+                                codec.GetPixels(fullBitmap.Info, fullBitmap.GetPixels());
+                                fullBitmap.ScalePixels(bitmap, SKFilterQuality.High);
+                            }
+                        }
+
+                        return bitmap;
+                    }
+                }
+            }
+            catch
+            {
+                return null;
+            }
+        }
+    }
+}

src/SkiaSharp/RelayCommand.cs

@@ -0,0 +1,46 @@
+// This Source Code Form is subject to the terms of the Mozilla Public
+// License, v. 2.0. If a copy of the MPL was not distributed with this
+// file, You can obtain one at http://mozilla.org/MPL/2.0/.
+
+using System;
+using System.ComponentModel;
+using System.Runtime.CompilerServices;
+
+namespace WinDynamicDesktop.SkiaSharp
+{
+    public class RelayCommand : ICommand
+    {
+        private readonly Action execute;
+        private readonly Func<bool> canExecute;
+
+        public event EventHandler CanExecuteChanged;
+
+        public RelayCommand(Action execute, Func<bool> canExecute = null)
+        {
+            this.execute = execute;
+            this.canExecute = canExecute;
+        }
+
+        public bool CanExecute(object parameter)
+        {
+            return canExecute?.Invoke() ?? true;
+        }
+
+        public void Execute(object parameter)
+        {
+            execute?.Invoke();
+        }
+
+        public void RaiseCanExecuteChanged()
+        {
+            CanExecuteChanged?.Invoke(this, EventArgs.Empty);
+        }
+    }
+
+    public interface ICommand
+    {
+        event EventHandler CanExecuteChanged;
+        bool CanExecute(object parameter);
+        void Execute(object parameter);
+    }
+}