Use interfaces in page transitions.

Perspex.Animation/Animate.cs

@@ -103,7 +103,7 @@ namespace Perspex.Animation
         /// <param name="duration">The duration of the animation.</param>
         /// <returns>An <see cref="Animation"/> that can be used to track or stop the animation.</returns>
         public static Animation Property(
-            PerspexObject target,
+            IObservablePropertyBag target,
             PerspexProperty property,
             object start,
             object finish,
@@ -126,7 +126,7 @@ namespace Perspex.Animation
         /// <param name="duration">The duration of the animation.</param>
         /// <returns>An <see cref="Animation"/> that can be used to track or stop the animation.</returns>
         public static Animation<T> Property<T>(
-            PerspexObject target,
+            IObservablePropertyBag target,
             PerspexProperty<T> property,
             T start,
             T finish,

Perspex.Base/IObservablePropertyBag.cs

@@ -27,11 +27,34 @@ namespace Perspex
             IObservable<object> source,
             BindingPriority priority = BindingPriority.LocalValue);
 
+        /// <summary>
+        /// Binds a <see cref="PerspexProperty"/> to an observable.
+        /// </summary>
+        /// <typeparam name="T">The type of the property.</typeparam>
+        /// <param name="property">The property.</param>
+        /// <param name="source">The observable.</param>
+        /// <param name="priority">The priority of the binding.</param>
+        /// <returns>
+        /// A disposable which can be used to terminate the binding.
+        /// </returns>
+        IDisposable Bind<T>(
+            PerspexProperty<T> property,
+            IObservable<T> source,
+            BindingPriority priority = BindingPriority.LocalValue);
+
         /// <summary>
         /// Gets an observable for a <see cref="PerspexProperty"/>.
         /// </summary>
         /// <param name="property">The property.</param>
         /// <returns>An observable.</returns>
         IObservable<object> GetObservable(PerspexProperty property);
+
+        /// <summary>
+        /// Gets an observable for a <see cref="PerspexProperty"/>.
+        /// </summary>
+        /// <typeparam name="T">The type of the property.</typeparam>
+        /// <param name="property">The property.</param>
+        /// <returns>An observable.</returns>
+        IObservable<T> GetObservable<T>(PerspexProperty<T> property);
     }
 }

Perspex.Base/IPropertyBag.cs

@@ -24,6 +24,14 @@ namespace Perspex
         /// <returns>The value.</returns>
         object GetValue(PerspexProperty property);
 
+        /// <summary>
+        /// Gets a <see cref="PerspexProperty"/> value.
+        /// </summary>
+        /// <typeparam name="T">The type of the property.</typeparam>
+        /// <param name="property">The property.</param>
+        /// <returns>The value.</returns>
+        T GetValue<T>(PerspexProperty<T> property);
+
         /// <summary>
         /// Checks whether a <see cref="PerspexProperty"/> is registered on this object.
         /// </summary>
@@ -45,5 +53,14 @@ namespace Perspex
         /// <param name="value">The value.</param>
         /// <param name="priority">The priority of the value.</param>
         void SetValue(PerspexProperty property, object value, BindingPriority priority = BindingPriority.LocalValue);
+
+        /// <summary>
+        /// Sets a <see cref="PerspexProperty"/> value.
+        /// </summary>
+        /// <typeparam name="T">The type of the property.</typeparam>
+        /// <param name="property">The property.</param>
+        /// <param name="value">The value.</param>
+        /// <param name="priority">The priority of the value.</param>
+        void SetValue<T>(PerspexProperty<T> property, T value, BindingPriority priority = BindingPriority.LocalValue);
     }
 }

Perspex.SceneGraph/Animation/CrossFade.cs

@@ -11,16 +11,38 @@ namespace Perspex.Animation
     using System.Reactive.Threading.Tasks;
     using System.Threading.Tasks;
 
+    /// <summary>
+    /// Defines a cross-fade animation between two <see cref="IVisual"/>s.
+    /// </summary>
     public class CrossFade : IPageTransition
     {
+        /// <summary>
+        /// Initializes a new instance of the <see cref="CrossFade"/> class.
+        /// </summary>
+        /// <param name="duration">The duration of the animation.</param>
         public CrossFade(TimeSpan duration)
         {
             this.Duration = duration;
         }
 
+        /// <summary>
+        /// Gets the duration of the animation.
+        /// </summary>
         public TimeSpan Duration { get; }
 
-        public async Task Start(Visual from, Visual to, bool forward)
+        /// <summary>
+        /// Starts the animation.
+        /// </summary>
+        /// <param name="from">
+        /// The control that is being transitioned away from. May be null.
+        /// </param>
+        /// <param name="to">
+        /// The control that is being transitioned to. May be null.
+        /// </param>
+        /// <returns>
+        /// A <see cref="Task"/> that tracks the progress of the animation.
+        /// </returns>
+        public async Task Start(IVisual from, IVisual to)
         {
             var tasks = new List<Task>();
 
@@ -32,7 +54,7 @@ namespace Perspex.Animation
             if (from != null)
             {
                 tasks.Add(Animate.Property(
-                    from,
+                    (IObservablePropertyBag)from,
                     Visual.OpacityProperty,
                     from.Opacity,
                     0,
@@ -46,7 +68,7 @@ namespace Perspex.Animation
                 to.IsVisible = true;
 
                 tasks.Add(Animate.Property(
-                    to,
+                    (IObservablePropertyBag)to,
                     Visual.OpacityProperty,
                     0,
                     1,
@@ -64,5 +86,25 @@ namespace Perspex.Animation
 
             to.Opacity = 1;
         }
+
+        /// <summary>
+        /// Starts the animation.
+        /// </summary>
+        /// <param name="from">
+        /// The control that is being transitioned away from. May be null.
+        /// </param>
+        /// <param name="to">
+        /// The control that is being transitioned to. May be null.
+        /// </param>
+        /// <param name="forward">
+        /// Unused for cross-fades.
+        /// </param>
+        /// <returns>
+        /// A <see cref="Task"/> that tracks the progress of the animation.
+        /// </returns>
+        Task IPageTransition.Start(IVisual from, IVisual to, bool forward)
+        {
+            return this.Start(from, to);
+        }
     }
 }

Perspex.SceneGraph/Animation/IPageTransition.cs

@@ -8,8 +8,26 @@ namespace Perspex.Animation
 {
     using System.Threading.Tasks;
 
+    /// <summary>
+    /// Interface for animations that transition between two pages.
+    /// </summary>
     public interface IPageTransition
     {
-        Task Start(Visual from, Visual to, bool forward);
+        /// <summary>
+        /// Starts the animation.
+        /// </summary>
+        /// <param name="from">
+        /// The control that is being transitioned away from. May be null.
+        /// </param>
+        /// <param name="to">
+        /// The control that is being transitioned to. May be null.
+        /// </param>
+        /// <param name="forward">
+        /// If the animation is bidirectional, controls the direction of the animation.
+        /// </param>
+        /// <returns>
+        /// A <see cref="Task"/> that tracks the progress of the animation.
+        /// </returns>
+        Task Start(IVisual from, IVisual to, bool forward);
     }
 }

Perspex.SceneGraph/Animation/PageSlide.cs

@@ -22,7 +22,7 @@ namespace Perspex.Animation
 
         public TimeSpan Duration { get; }
 
-        public async Task Start(Visual from, Visual to, bool forward)
+        public async Task Start(IVisual from, IVisual to, bool forward)
         {
             var tasks = new List<Task>();
             var parent = GetVisualParent(from, to);

Perspex.SceneGraph/IVisual.cs

@@ -31,7 +31,7 @@ namespace Perspex
         /// <summary>
         /// Gets a value indicating whether the scene graph node should be clipped to its bounds.
         /// </summary>
-        bool ClipToBounds { get; }
+        bool ClipToBounds { get; set; }
 
         /// <summary>
         /// Gets a value indicating whether this scene graph node is attached to a visual root.
@@ -44,24 +44,24 @@ namespace Perspex
         bool IsEffectivelyVisible { get; }
 
         /// <summary>
-        /// Gets a value indicating whether this scene graph node is visible.
+        /// Gets or sets a value indicating whether this scene graph node is visible.
         /// </summary>
-        bool IsVisible { get; }
+        bool IsVisible { get; set; }
 
         /// <summary>
-        /// Gets the opacity of the scene graph node.
+        /// Gets or sets the opacity of the scene graph node.
         /// </summary>
-        double Opacity { get; }
+        double Opacity { get; set; }
 
         /// <summary>
-        /// Gets the render transform of the scene graph node.
+        /// Gets or sets the render transform of the scene graph node.
         /// </summary>
-        Transform RenderTransform { get; }
+        Transform RenderTransform { get; set; }
 
         /// <summary>
-        /// Gets the transform origin of the scene graph node.
+        /// Gets or sets the transform origin of the scene graph node.
         /// </summary>
-        Origin TransformOrigin { get; }
+        Origin TransformOrigin { get; set; }
 
         /// <summary>
         /// Gets the scene graph node's child nodes.
@@ -74,9 +74,9 @@ namespace Perspex
         IVisual VisualParent { get; }
 
         /// <summary>
-        /// Gets the Z index of the node.
+        /// Gets or sets the Z index of the node.
         /// </summary>
-        int ZIndex { get; }
+        int ZIndex { get; set; }
 
         /// <summary>
         /// Renders the scene graph node to a <see cref="IDrawingContext"/>.

Tests/Perspex.Styling.UnitTests/SelectorTests_Child.cs

@@ -124,6 +124,26 @@ namespace Perspex.Styling.UnitTests
             {
                 throw new NotImplementedException();
             }
+
+            public IDisposable Bind<T>(PerspexProperty<T> property, IObservable<T> source, BindingPriority priority = BindingPriority.LocalValue)
+            {
+                throw new NotImplementedException();
+            }
+
+            public IObservable<T> GetObservable<T>(PerspexProperty<T> property)
+            {
+                throw new NotImplementedException();
+            }
+
+            public T GetValue<T>(PerspexProperty<T> property)
+            {
+                throw new NotImplementedException();
+            }
+
+            public void SetValue<T>(PerspexProperty<T> property, T value, BindingPriority priority = BindingPriority.LocalValue)
+            {
+                throw new NotImplementedException();
+            }
         }
 
         public class TestLogical1 : TestLogical

Tests/Perspex.Styling.UnitTests/SelectorTests_Descendent.cs

@@ -156,6 +156,26 @@ namespace Perspex.Styling.UnitTests
             {
                 throw new NotImplementedException();
             }
+
+            public IDisposable Bind<T>(PerspexProperty<T> property, IObservable<T> source, BindingPriority priority = BindingPriority.LocalValue)
+            {
+                throw new NotImplementedException();
+            }
+
+            public IObservable<T> GetObservable<T>(PerspexProperty<T> property)
+            {
+                throw new NotImplementedException();
+            }
+
+            public T GetValue<T>(PerspexProperty<T> property)
+            {
+                throw new NotImplementedException();
+            }
+
+            public void SetValue<T>(PerspexProperty<T> property, T value, BindingPriority priority = BindingPriority.LocalValue)
+            {
+                throw new NotImplementedException();
+            }
         }
 
         public class TestLogical1 : TestLogical

Tests/Perspex.Styling.UnitTests/TestControlBase.cs

@@ -68,5 +68,25 @@ namespace Perspex.Styling.UnitTests
         {
             throw new NotImplementedException();
         }
+
+        public IDisposable Bind<T>(PerspexProperty<T> property, IObservable<T> source, BindingPriority priority = BindingPriority.LocalValue)
+        {
+            throw new NotImplementedException();
+        }
+
+        public IObservable<T> GetObservable<T>(PerspexProperty<T> property)
+        {
+            throw new NotImplementedException();
+        }
+
+        public T GetValue<T>(PerspexProperty<T> property)
+        {
+            throw new NotImplementedException();
+        }
+
+        public void SetValue<T>(PerspexProperty<T> property, T value, BindingPriority priority = BindingPriority.LocalValue)
+        {
+            throw new NotImplementedException();
+        }
     }
 }

Tests/Perspex.Styling.UnitTests/TestTemplatedControl.cs

@@ -76,5 +76,20 @@ namespace Perspex.Styling.UnitTests
         {
             throw new NotImplementedException();
         }
+
+        public IDisposable Bind<T>(PerspexProperty<T> property, IObservable<T> source, BindingPriority priority = BindingPriority.LocalValue)
+        {
+            throw new NotImplementedException();
+        }
+
+        public T GetValue<T>(PerspexProperty<T> property)
+        {
+            throw new NotImplementedException();
+        }
+
+        public void SetValue<T>(PerspexProperty<T> property, T value, BindingPriority priority = BindingPriority.LocalValue)
+        {
+            throw new NotImplementedException();
+        }
     }
 }