Core(Gtk): fix image resize

Implement WidthRequest and HeightRequest mappings for Image.

src/Core/src/Handlers/Image/ImageHandler.Gtk.cs

@@ -40,6 +40,39 @@ void OnSetImageSource(Pixbuf? obj)
 			PlatformView.Image = obj;
 		}
 
+		static int? Request(double viewSize) => viewSize >= 0 ? (int)Math.Round(viewSize) : null;
+		private void UpdateWidthRequest(IImage image)
+		{
+			var widthRequest = Request(image.Width * PlatformView.ScaleFactor);
+
+			if (widthRequest is not null && widthRequest != PlatformView.WidthRequest && widthRequest != PlatformView.AllocatedWidth)
+			{
+				PlatformView.ChangeWidth(widthRequest.Value);
+				PlatformView.QueueResize();
+			}
+		}
+
+		private void UpdateHeightRequest(IImage image)
+		{
+			var heightRequest = Request(image.Height * PlatformView.ScaleFactor);
+
+			if (heightRequest is not null && heightRequest != PlatformView.WidthRequest && heightRequest != PlatformView.AllocatedWidth)
+			{
+				PlatformView.ChangeHeight(heightRequest.Value);
+				PlatformView.QueueResize();
+			}
+		}
+
+		public static void MapWidthRequest(IImageHandler handler, IImage view)
+		{
+			((ImageHandler)handler).UpdateWidthRequest(view);
+		}
+
+		public static void MapHeightRequest(IImageHandler handler, IImage view)
+		{
+			((ImageHandler)handler).UpdateHeightRequest(view);
+		}
+
 	}
 
 }

src/Core/src/Handlers/Image/ImageHandler.cs

@@ -26,6 +26,10 @@ public partial class ImageHandler : IImageHandler
 			[nameof(IImage.Aspect)] = MapAspect,
 			[nameof(IImage.IsAnimationPlaying)] = MapIsAnimationPlaying,
 			[nameof(IImage.Source)] = MapSource,
+#if GTK
+			["WidthRequest"] = MapWidthRequest,
+			["HeightRequest"] = MapHeightRequest,
+#endif
 		};
 
 		public static CommandMapper<IImage, IImageHandler> CommandMapper = new(ViewHandler.ViewCommandMapper)

src/Core/src/Platform/Gtk/ImageView.cs

@@ -1,3 +1,5 @@
+using Gdk;
+
 namespace Microsoft.Maui.Platform
 {
 
@@ -9,11 +11,60 @@ namespace Microsoft.Maui.Platform
 
 	public class ImageView : Gtk.Image
 	{
+		// OriginalSizeBuf is added so when we want to resize the image using Pixbuf we can access the
+		// initial Pixbuf and resize that. 
+		Pixbuf? _originalSizeBuf;
+		// Image might be null because it is possible to have a WidthRequest before Pixbuf has a value.
+		// In this case, we'll just save the value, and once Pixbuf is initialized we'll update its size
+		// to have the saved values
+		int? _lastRequestedWidth;
+		int? _lastRequestedHeight;
 
-		public Gdk.Pixbuf? Image
+		public Pixbuf? Image
 		{
 			get => Pixbuf;
-			set => Pixbuf = value;
+			set
+			{
+				_originalSizeBuf = value;
+				if (_lastRequestedHeight is not null || _lastRequestedWidth is not null)
+				{
+					Pixbuf = _originalSizeBuf?.ScaleSimple(
+						_lastRequestedWidth ?? _originalSizeBuf.Width,
+						_lastRequestedHeight ?? _originalSizeBuf.Height,
+						InterpType.Bilinear
+					);
+				}
+				else
+				{
+					Pixbuf = value;
+				}
+			}
+		}
+
+		internal void ChangeHeight(int height)
+		{
+			if (Image is null)
+			{
+				_lastRequestedHeight = height;
+			}
+			else
+			{
+				var newBuf = _originalSizeBuf?.ScaleSimple(Pixbuf.Width, height, InterpType.Bilinear);
+				Pixbuf = newBuf;
+			}
+		}
+
+		internal void ChangeWidth(int width)
+		{
+			if (Image is null)
+			{
+				_lastRequestedWidth = width;
+			}
+			else
+			{
+				var newBuf = _originalSizeBuf?.ScaleSimple(width, Pixbuf.Height, InterpType.Bilinear);
+				Pixbuf = newBuf;
+			}
 		}
 
 	}