Measure geometry including stroke.

Perspex.Direct2D1/Media/GeometryImpl.cs

@@ -6,6 +6,8 @@
 
 namespace Perspex.Direct2D1.Media
 {
+    using System;
+    using Perspex.Media;
     using Perspex.Platform;
 
     public abstract class GeometryImpl : IGeometryImpl
@@ -20,5 +22,7 @@ namespace Perspex.Direct2D1.Media
             get;
             protected set;
         }
+
+        public abstract Rect GetRenderBounds(double strokeThickness);
     }
 }

Perspex.Direct2D1/Media/StreamGeometryImpl.cs

@@ -28,6 +28,11 @@ namespace Perspex.Direct2D1.Media
             get { return geometry.GetBounds().ToPerspex(); }
         }
 
+        public override Rect GetRenderBounds(double strokeThickness)
+        {
+            return geometry.GetWidenedBounds((float)strokeThickness).ToPerspex();
+        }
+
         public IStreamGeometryContextImpl Open()
         {
             return new StreamGeometryContextImpl(geometry.Open());

Perspex/Media/Geometry.cs

@@ -20,5 +20,10 @@ namespace Perspex.Media
             get;
             protected set;
         }
+
+        public Rect GetRenderBounds(double strokeThickness)
+        {
+            return this.PlatformImpl.GetRenderBounds(strokeThickness);
+        }
     }
 }

Perspex/Platform/IGeometryImpl.cs

@@ -6,8 +6,12 @@
 
 namespace Perspex.Platform
 {
+    using Perspex.Media;
+
     public interface IGeometryImpl
     {
         Rect Bounds { get; }
+
+        Rect GetRenderBounds(double strokeThickness);
     }
 }

Perspex/Shapes/Rectangle.cs

@@ -16,12 +16,12 @@ namespace Perspex.Shapes
 
         public override Geometry DefiningGeometry
         {
-            get { return new RectangleGeometry(new Rect(size)); }
+            get { return new RectangleGeometry(new Rect(0, 0, this.Width, this.Height)); }
         }
 
         protected override Size MeasureOverride(Size availableSize)
         {
-            return new Size(this.Width, this.Height);
+            return this.DefiningGeometry.GetRenderBounds(this.StrokeThickness).Size;
         }
 
         protected override Size ArrangeOverride(Size finalSize)

Perspex/Shapes/Shape.cs

@@ -60,7 +60,7 @@ namespace Perspex.Shapes
 
         protected override Size MeasureOverride(Size availableSize)
         {
-            Rect shapeBounds = this.RenderedGeometry.Bounds;
+            Rect shapeBounds = this.RenderedGeometry.GetRenderBounds(this.StrokeThickness);
             double width = this.Width;
             double height = this.Height;
             double desiredX = availableSize.Width;