Matrix stuff

src/Avalonia.Base/Rendering/Composition/Server/CompositionMatrix.cs

@@ -152,7 +152,7 @@ public struct CompositionMatrix(Matrix matrix)
         var actual = res.ToMatrix();
         if (!expected.Equals(actual))
         {
-            Console.WriteLine("BUG!");
+            throw new InvalidOperationException("BUG");
         }
 
         return res;
@@ -224,7 +224,7 @@ public struct CompositionMatrix(Matrix matrix)
         var expected = p.Transform(ToMatrix());
         if (res != expected)
         {
-            Console.WriteLine("Bug!");
+            throw new InvalidOperationException("BUG");
         }
 
         return res;

src/Avalonia.Base/Rendering/Composition/Server/ServerCompositionDrawListVisual.cs

@@ -43,7 +43,7 @@ internal class ServerCompositionDrawListVisual : ServerCompositionContainerVisua
     protected override void RenderCore(ServerVisualRenderContext context, LtrbRect currentTransformedClip)
     {
         if (_renderCommands != null 
-            && context.ShouldRenderOwnContent(this, currentTransformedClip))
+            && context.ShouldRenderOwnContent(this, ref currentTransformedClip))
         {
             _renderCommands.Render(context.Canvas);
         }

src/Skia/Avalonia.Skia/SkiaSharpExtensions.cs

@@ -174,13 +174,36 @@ namespace Avalonia.Skia
 
             return sm;
         }
-        
-        
+
+
         public static SKMatrix44 ToSKMatrix44(this CompositionMatrix m)
+#if DEBUG_COMPOSITION_MATRIX
+        {
+            var rv = ToSKMatrix44Core(m);
+            var expected = m.ToMatrix().ToSKMatrix44();
+            if (rv != expected)
+                throw new Exception();
+            return rv;
+        }
+        public static SKMatrix44 ToSKMatrix44Core(CompositionMatrix m)
+#endif
         {
             if (m.GuaranteedIdentity)
                 return SKMatrix44.Identity;
 
+            if (m.GuaranteedTranslateAndScaleOnly)
+            {
+                return new SKMatrix44()
+                {
+                    M00 = (float)m.ScaleX,
+                    M11 = (float)m.ScaleY,
+                    M22 = 1,
+                    M30 = (float)m.OffsetX,
+                    M31 = (float)m.OffsetY,
+                    M33 = 1
+                };
+            }
+
             return new SKMatrix44
             {
                 M00 = (float)m.ScaleX,