Use GDK to scale images instead of cairo

src/Gtk/Avalonia.Cairo/Media/DrawingContext.cs

@@ -77,40 +77,25 @@ namespace Avalonia.Cairo.Media
         /// <param name="destRect">The rect in the output to draw to.</param>
         public void DrawImage(IBitmap bitmap, double opacity, Rect sourceRect, Rect destRect)
         {
-            var impl = bitmap.PlatformImpl as BitmapImpl;
-            var size = new Size(impl.PixelWidth, impl.PixelHeight);
-            var scale = new Vector(destRect.Width / sourceRect.Width, destRect.Height / sourceRect.Height);
-
-            _context.Save();
-            _context.Scale(scale.X, scale.Y);
-            destRect /= scale;
-
-			if (opacityOverride < 1.0f) {
-				_context.PushGroup ();
-				Gdk.CairoHelper.SetSourcePixbuf (
-					_context, 
-					impl, 
-					-sourceRect.X + destRect.X, 
-					-sourceRect.Y + destRect.Y);
-
-				_context.Rectangle (destRect.ToCairo ());
-				_context.Fill ();
-				_context.PopGroupToSource ();
-				_context.PaintWithAlpha (opacityOverride);
-			} else {
-				_context.PushGroup ();
-				Gdk.CairoHelper.SetSourcePixbuf (
-					_context, 
-					impl, 
-					-sourceRect.X + destRect.X, 
-					-sourceRect.Y + destRect.Y);
-
-                _context.Rectangle (destRect.ToCairo ());
-                _context.Fill ();
-                _context.PopGroupToSource ();
-                _context.PaintWithAlpha (opacityOverride);			
-            }
-            _context.Restore();
+			var impl = bitmap.PlatformImpl as BitmapImpl;
+			var size = new Size(impl.PixelWidth, impl.PixelHeight);
+			var scale = new Vector(destRect.Width / sourceRect.Width, destRect.Height / sourceRect.Height);
+
+			_context.Save();
+
+			Gdk.CairoHelper.SetSourcePixbuf (
+				_context, 
+				impl, 
+				-sourceRect.X + destRect.X, 
+				-sourceRect.Y + destRect.Y);
+			impl.Scale (impl, 0, 0, (int)destRect.Width, (int)destRect.Height, 0, 0, scale.X, scale.Y, Gdk.InterpType.Bilinear);
+
+			_context.PushGroup ();
+			_context.Rectangle (destRect.ToCairo ());
+			_context.Fill ();
+			_context.PopGroupToSource ();
+			_context.PaintWithAlpha (opacityOverride);		
+			_context.Restore();
         }
 
         /// <summary>