Add createscaled bitmap

src/Avalonia.Visuals/Media/Imaging/Bitmap.cs

@@ -23,6 +23,12 @@ namespace Avalonia.Media.Imaging
             return new Bitmap(factory.LoadBitmapToHeight(stream, height, interpolationMode));
         }
 
+        public static Bitmap CreateScaledBitmap(Bitmap src, PixelSize destinationSize, BitmapInterpolationMode interpolationMode = BitmapInterpolationMode.HighQuality)
+        {
+            IPlatformRenderInterface factory = AvaloniaLocator.Current.GetService<IPlatformRenderInterface>();
+            return new Bitmap(factory.ResizeBitmap(src.PlatformImpl.Item, destinationSize, interpolationMode));
+        }
+
         /// <summary>
         /// Initializes a new instance of the <see cref="Bitmap"/> class.
         /// </summary>

src/Avalonia.Visuals/Platform/IPlatformRenderInterface.cs

@@ -114,6 +114,8 @@ namespace Avalonia.Platform
         /// <returns>An <see cref="IBitmapImpl"/>.</returns>
         IBitmapImpl LoadBitmapToHeight(Stream stream, int height, BitmapInterpolationMode interpolationMode = BitmapInterpolationMode.HighQuality);
 
+        IBitmapImpl ResizeBitmap(IBitmapImpl bitmapImpl, PixelSize destinationSize, BitmapInterpolationMode interpolationMode = BitmapInterpolationMode.HighQuality);
+
         /// <summary>
         /// Loads a bitmap implementation from a pixels in memory.
         /// </summary>

src/Skia/Avalonia.Skia/ImmutableBitmap.cs

@@ -40,6 +40,20 @@ namespace Avalonia.Skia
             }
         }
 
+        public ImmutableBitmap(ImmutableBitmap src, PixelSize destinationSize, BitmapInterpolationMode interpolationMode)
+        {            
+            SKImageInfo info = new SKImageInfo(destinationSize.Width, destinationSize.Height, SKColorType.Bgra8888);
+            SKImage output = SKImage.Create(info);
+            src._image.ScalePixels(output.PeekPixels(), interpolationMode.ToSKFilterQuality());
+
+            _image = output;
+
+            PixelSize = new PixelSize(_image.Width, _image.Height);
+
+            // TODO: Skia doesn't have an API for DPI.
+            Dpi = new Vector(96, 96);
+        }
+
         // NOTE, putting the stream before options in the parameters, causes an exception
         // inside SKCodec.Create with optimized code. Probably a bug in .net compiler.
         // Other option is to have the argument order as desired and use PreserveSig options.

src/Skia/Avalonia.Skia/PlatformRenderInterface.cs

@@ -109,6 +109,18 @@ namespace Avalonia.Skia
             return new ImmutableBitmap(size, dpi, stride, format, data);
         }
 
+        public IBitmapImpl ResizeBitmap(IBitmapImpl bitmapImpl, PixelSize destinationSize, BitmapInterpolationMode interpolationMode = BitmapInterpolationMode.HighQuality)
+        {
+            if (bitmapImpl is ImmutableBitmap ibmp)
+            {
+                return new ImmutableBitmap(ibmp, destinationSize, interpolationMode);
+            }
+            else
+            {
+                throw new Exception("Invalid source bitmap type.");
+            }
+        }
+
         /// <inheritdoc />
         public IRenderTargetBitmapImpl CreateRenderTargetBitmap(PixelSize size, Vector dpi)
         {

src/Windows/Avalonia.Direct2D1/Direct2D1Platform.cs

@@ -201,6 +201,11 @@ namespace Avalonia.Direct2D1
             throw new NotImplementedException();
         }
 
+        public IBitmapImpl ResizeBitmap(IBitmapImpl bitmapImpl, PixelSize destinationSize, BitmapInterpolationMode interpolationMode = BitmapInterpolationMode.HighQuality)
+        {
+            throw new NotImplementedException();
+        }
+
         public IBitmapImpl LoadBitmap(PixelFormat format, IntPtr data, PixelSize size, Vector dpi, int stride)
         {
             return new WicBitmapImpl(format, data, size, dpi, stride);