Added simple animation.

Perspex.Controls/Presenters/ScrollContentPresenter.cs

@@ -31,6 +31,7 @@ namespace Perspex.Controls.Presenters
 
         static ScrollContentPresenter()
         {
+            ClipToBoundsProperty.OverrideDefaultValue(typeof(ScrollContentPresenter), true);
             Control.AffectsArrange(OffsetProperty);
         }
 

Perspex.Controls/Window.cs

@@ -164,7 +164,9 @@ namespace Perspex.Controls
 
         private void HandleRenderNeeded()
         {
-            this.dispatcher.InvokeAsync(this.RenderVisualTree, DispatcherPriority.Render);
+            this.dispatcher.InvokeAsync(
+                () => this.impl.Invalidate(new Rect(this.ClientSize)), 
+                DispatcherPriority.Render);
         }
 
         private void HandlePaint(Rect rect, IPlatformHandle handle)
@@ -186,13 +188,5 @@ namespace Perspex.Controls
             this.LayoutManager.ExecuteLayoutPass();
             this.impl.Invalidate(new Rect(this.ClientSize));
         }
-
-        private void RenderVisualTree()
-        {
-            if (!this.LayoutManager.LayoutQueued)
-            {
-                this.impl.Invalidate(new Rect(this.ClientSize));
-            }
-        }
     }
 }

Perspex.SceneGraph/IVisual.cs

@@ -28,6 +28,11 @@ namespace Perspex
         /// <returns></returns>
         Rect Bounds { get; }
 
+        /// <summary>
+        /// Gets a value indicating whether the scene graph node should be clipped to its bounds.
+        /// </summary>
+        bool ClipToBounds { get; }
+
         /// <summary>
         /// Gets a value indicating whether this scene graph node is visible.
         /// </summary>

Perspex.SceneGraph/Media/ITransform.cs

@@ -6,8 +6,12 @@
 
 namespace Perspex.Media
 {
+    using System;
+
     public interface ITransform
     {
+        event EventHandler Changed;
+
         Matrix Value { get; }
     }
 }

Perspex.SceneGraph/Media/MatrixTransform.cs

@@ -6,6 +6,8 @@
 
 namespace Perspex.Media
 {
+    using System;
+
     public class MatrixTransform : Transform
     {
         public static readonly PerspexProperty<Matrix> MatrixProperty =
@@ -13,9 +15,11 @@ namespace Perspex.Media
 
         public MatrixTransform()
         {
+            this.GetObservable(MatrixProperty).Subscribe(_ => this.RaiseChanged());
         }
 
         public MatrixTransform(Matrix matrix)
+            : this()
         {
             this.Matrix = matrix;
         }

Perspex.SceneGraph/Media/RotateTransform.cs

@@ -6,6 +6,8 @@
 
 namespace Perspex.Media
 {
+    using System;
+
     public class RotateTransform : Transform
     {
         public static readonly PerspexProperty<double> AngleProperty =
@@ -13,9 +15,11 @@ namespace Perspex.Media
 
         public RotateTransform()
         {
+            this.GetObservable(AngleProperty).Subscribe(_ => this.RaiseChanged());
         }
 
         public RotateTransform(double angle)
+            : this()
         {
             this.Angle = angle;
         }

Perspex.SceneGraph/Media/Transform.cs

@@ -6,8 +6,20 @@
 
 namespace Perspex.Media
 {
+    using System;
+
     public abstract class Transform : PerspexObject, ITransform
     {
+        public event EventHandler Changed;
+
         public abstract Matrix Value { get; }
+
+        protected void RaiseChanged()
+        {
+            if (this.Changed != null)
+            {
+                this.Changed(this, EventArgs.Empty);
+            }
+        }
     }
 }

Perspex.SceneGraph/Visual.cs

@@ -10,12 +10,16 @@ namespace Perspex
     using System.Collections.Generic;
     using System.Collections.Specialized;
     using System.Linq;
+    using System.Reactive.Linq;
     using Perspex.Media;
     using Perspex.Rendering;
     using Splat;
 
     public class Visual : PerspexObject, IVisual
     {
+        public static readonly PerspexProperty<bool> ClipToBoundsProperty =
+            PerspexProperty.Register<Visual, bool>("ClipToBounds");
+
         public static readonly PerspexProperty<bool> IsVisibleProperty =
             PerspexProperty.Register<Visual, bool>("IsVisible", true);
 
@@ -37,6 +41,7 @@ namespace Perspex
         static Visual()
         {
             AffectsRender(IsVisibleProperty);
+            RenderTransformProperty.Changed.Subscribe(RenderTransformChanged);
         }
 
         public Visual()
@@ -45,6 +50,12 @@ namespace Perspex
             this.visualChildren.CollectionChanged += this.VisualChildrenChanged;
         }
 
+        public bool ClipToBounds
+        {
+            get { return this.GetValue(ClipToBoundsProperty); }
+            set { this.SetValue(ClipToBoundsProperty, value); }
+        }
+
         public bool IsVisible
         {
             get { return this.GetValue(IsVisibleProperty); }
@@ -197,6 +208,34 @@ namespace Perspex
             return result;
         }
 
+        private static void RenderTransformChanged(PerspexPropertyChangedEventArgs e)
+        {
+            var sender = e.Sender as Visual;
+
+            if (sender != null)
+            {
+                var oldValue = e.OldValue as ITransform;
+                var newValue = e.NewValue as ITransform;
+
+                if (oldValue != null)
+                {
+                    oldValue.Changed -= sender.RenderTransformChanged;
+                }
+
+                if (newValue != null)
+                {
+                    newValue.Changed += sender.RenderTransformChanged;
+                }
+
+                sender.InvalidateVisual();
+            }
+        }
+
+        private void RenderTransformChanged(object sender, EventArgs e)
+        {
+            this.InvalidateVisual();
+        }
+
         private void SetVisualParent(Visual value)
         {
             if (this.visualParent != value)

TestApplication/Program.cs

@@ -1,7 +1,9 @@
-using System.Reactive.Linq;
+using System;
+using System.Reactive.Linq;
 using Perspex;
 using Perspex.Controls;
 using Perspex.Controls.Primitives;
+using Perspex.Controls.Shapes;
 using Perspex.Diagnostics;
 using Perspex.Layout;
 using Perspex.Media;
@@ -132,6 +134,7 @@ namespace TestApplication
                                 ListsTab(),
                                 SlidersTab(),
                                 LayoutTab(),
+                                AnimationsTab(),
                             }
                         },
                         new TextBlock
@@ -430,5 +433,43 @@ namespace TestApplication
                 }
             };
         }
+
+        private static TabItem AnimationsTab()
+        {
+            Rectangle rect1;
+
+            var result = new TabItem
+            {
+                Header = "Animations",
+                Content = new Grid
+                {
+                    ColumnDefinitions = new ColumnDefinitions
+                    {
+                        new ColumnDefinition(1, GridUnitType.Star),
+                    },
+                    Children = new Controls
+                    {
+                        (rect1 = new Rectangle
+                        {
+                            Width = 100,
+                            Height = 100,
+                            HorizontalAlignment = HorizontalAlignment.Center,
+                            VerticalAlignment = VerticalAlignment.Center,
+                            Fill = Brushes.Crimson,
+                            RenderTransform = new RotateTransform(),
+                        }),
+                    },
+                },
+            };
+
+            Observable.Interval(TimeSpan.FromMilliseconds(10))
+                .Subscribe(x =>
+                {
+                    ((RotateTransform)rect1.RenderTransform).Angle = x;
+                });
+
+            return result;
+        }
+
     }
 }

Windows/Perspex.Direct2D1/Renderer.cs

@@ -133,7 +133,7 @@ namespace Perspex.Direct2D1
 
                 transform *= Matrix.Translation(visual.Bounds.Position);
 
-                using (context.PushClip(visual.Bounds))
+                using (visual.ClipToBounds ? context.PushClip(visual.Bounds) : null)
                 using (context.PushTransform(transform))
                 {
                     visual.Render(context);

Windows/Perspex.Win32/WindowImpl.cs

@@ -103,8 +103,6 @@ namespace Perspex.Win32
                 lpszClassName = this.className,
             };
 
-            System.Diagnostics.Debug.WriteLine("Registered class " + this.className);
-
             ushort atom = UnmanagedMethods.RegisterClassEx(ref wndClassEx);
 
             if (atom == 0)