Add rounded rect clip to drawing context.

src/Avalonia.Visuals/Media/DrawingContext.cs

@@ -282,6 +282,12 @@ namespace Avalonia.Media
         }
 
 
+        public PushedState PushClip(RoundedRect clip)
+        {
+            PlatformImpl.PushClip(clip);
+            return new PushedState(this, PushedState.PushedStateType.Clip);
+        }
+
         /// <summary>
         /// Pushes a clip rectangle.
         /// </summary>

src/Avalonia.Visuals/Platform/IDrawingContextImpl.cs

@@ -107,6 +107,12 @@ namespace Avalonia.Platform
         /// <param name="clip">The clip rectangle.</param>
         void PushClip(Rect clip);
 
+        /// <summary>
+        /// Pushes a clip rounded rectangle.
+        /// </summary>
+        /// <param name="clip">The clip rounded rectangle</param>
+        void PushClip(RoundedRect clip);
+
         /// <summary>
         /// Pops the latest pushed clip rectangle.
         /// </summary>

src/Avalonia.Visuals/Rendering/SceneGraph/IVisualNode.cs

@@ -26,6 +26,11 @@ namespace Avalonia.Rendering.SceneGraph
         /// </summary>
         Matrix Transform { get; }
 
+        /// <summary>
+        /// Gets the corner radius of visual. Contents are clipped to this radius.
+        /// </summary>
+        CornerRadius CornerRadius { get; }
+
         /// <summary>
         /// Gets the bounds of the node's geometry in global coordinates.
         /// </summary>

src/Avalonia.Visuals/Rendering/SceneGraph/VisualNode.cs

@@ -46,6 +46,9 @@ namespace Avalonia.Rendering.SceneGraph
         /// <inheritdoc/>
         public IVisualNode Parent { get; }
 
+        /// <inheritdoc/>
+        public CornerRadius CornerRadius { get; }
+
         /// <inheritdoc/>
         public Matrix Transform { get; set; }
 

src/Skia/Avalonia.Skia/DrawingContextImpl.cs

@@ -389,6 +389,12 @@ namespace Avalonia.Skia
             Canvas.ClipRect(clip.ToSKRect());
         }
 
+        public void PushClip(RoundedRect clip)
+        {
+            Canvas.Save();
+            Canvas.ClipRoundRect(clip.ToSKRoundRect());
+        }
+
         /// <inheritdoc />
         public void PopClip()
         {

src/Skia/Avalonia.Skia/SkiaSharpExtensions.cs

@@ -40,6 +40,21 @@ namespace Avalonia.Skia
             return new SKRect((float)r.X, (float)r.Y, (float)r.Right, (float)r.Bottom);
         }
 
+        public static SKRoundRect ToSKRoundRect(this RoundedRect r)
+        {
+            var rc = r.Rect.ToSKRect();
+            var result = new SKRoundRect();
+
+            result.SetRectRadii(rc,
+                   new[]
+                   {
+                        r.RadiiTopLeft.ToSKPoint(), r.RadiiTopRight.ToSKPoint(),
+                        r.RadiiBottomRight.ToSKPoint(), r.RadiiBottomLeft.ToSKPoint(),
+                   });            
+
+            return result;
+        }
+
         public static Rect ToAvaloniaRect(this SKRect r)
         {
             return new Rect(r.Left, r.Top, r.Right - r.Left, r.Bottom - r.Top);