*Added numerical transition classes.

*Disabled old animations code in CrossFade, PageSlide, CarouselPresenter and ProgressBar.

src/Avalonia.Animation/Transitions/DoubleTransition.cs

@@ -8,19 +8,16 @@ using System.Reactive.Linq;
 namespace Avalonia.Animation
 {
     /// <summary>
-    /// Transitions object that handles properties with <see cref="double"/> types.
+    /// Transition class that handles <see cref="AvaloniaProperty"/> with <see cref="double"/> types.
     /// </summary>  
     public class DoubleTransition : Transition<double>
     {
         /// <inheritdocs/>
-        public override void DoInterpolation(Animatable control, IObservable<double> progress, double oldValue, double newValue)
+        public override IObservable<double> DoInterpolation(IObservable<double> progress, double oldValue, double newValue)
         {
             var delta = newValue - oldValue;
-            var transition = progress.Select(p =>
-            {
-                return Easing.Ease(p) * delta + oldValue;
-            });
-            control.Bind(Property, transition.Select(p=>(object)p), Data.BindingPriority.Animation);
+            return progress
+                .Select(p => Easing.Ease(p) * delta + oldValue);
         }
     }
 }

src/Avalonia.Animation/Transitions/FloatTransition.cs

@@ -0,0 +1,23 @@
+// Copyright (c) The Avalonia Project. All rights reserved.
+// Licensed under the MIT license. See licence.md file in the project root for full license information.
+
+using Avalonia.Metadata;
+using System;
+using System.Reactive.Linq;
+
+namespace Avalonia.Animation
+{
+    /// <summary>
+    /// Transition class that handles <see cref="AvaloniaProperty"/> with <see cref="float"/> types.
+    /// </summary>  
+    public class FloatTransition : Transition<float>
+    {
+        /// <inheritdocs/>
+        public override IObservable<float> DoInterpolation(IObservable<double> progress, float oldValue, float newValue)
+        {
+            var delta = newValue - oldValue;
+            return progress
+                .Select(p => (float)Easing.Ease(p) * delta + oldValue);
+        }
+    }
+}

src/Avalonia.Animation/Transitions/ITransition.cs

@@ -0,0 +1,26 @@
+// Copyright (c) The Avalonia Project. All rights reserved.
+// Licensed under the MIT license. See licence.md file in the project root for full license information.
+
+using Avalonia.Metadata;
+using System;
+using System.Reactive.Linq;
+
+namespace Avalonia.Animation
+{
+    /// <summary>
+    /// Interface for <see cref="Transition{T}"/> objects.
+    /// </summary>
+    public interface ITransition
+    {
+        /// <summary>
+        /// Applies the transition to the specified <see cref="Animatable"/>.
+        /// </summary>
+        IDisposable Apply(Animatable control, object oldValue, object newValue);
+
+        /// <summary>
+        /// Gets the property to be animated.
+        /// </summary>
+        AvaloniaProperty Property { get; set; }
+    
+    }
+}

src/Avalonia.Animation/Transitions/IntegerTransition.cs

@@ -0,0 +1,23 @@
+// Copyright (c) The Avalonia Project. All rights reserved.
+// Licensed under the MIT license. See licence.md file in the project root for full license information.
+
+using Avalonia.Metadata;
+using System;
+using System.Reactive.Linq;
+
+namespace Avalonia.Animation
+{
+    /// <summary>
+    /// Transition class that handles <see cref="AvaloniaProperty"/> with <see cref="int"/> types.
+    /// </summary>  
+    public class IntegerTransition : Transition<int>
+    {
+        /// <inheritdocs/>
+        public override IObservable<int> DoInterpolation(IObservable<double> progress, int oldValue, int newValue)
+        {
+            var delta = newValue - oldValue;
+            return progress
+                .Select(p => (int)(Easing.Ease(p) * delta + oldValue));
+        }
+    }
+}

src/Avalonia.Animation/Transitions/Transition.cs

@@ -3,24 +3,10 @@
 
 using Avalonia.Metadata;
 using System;
+using System.Reactive.Linq;
 
 namespace Avalonia.Animation
 {
-    public interface ITransition
-    {
-        /// <summary>
-        /// Applies the transition to the specified <see cref="Animatable"/>.
-        /// </summary>
-        void Apply(Animatable control, object oldValue, object newValue);
-
-        /// <summary>
-        /// Gets the property to be animated.
-        /// </summary>
-        AvaloniaProperty Property { get; set; }
-
-
-    }
-
     /// <summary>
     /// Defines how a property should be animated using a transition.
     /// </summary>
@@ -49,7 +35,7 @@ namespace Avalonia.Animation
             {
                 if (!(typeof(T) == value.PropertyType))                
                     throw new InvalidCastException
-                        ($"Invalid property type {typeof(T).Name} for this {GetType().Name}");
+                        ($"Invalid property type \"{typeof(T).Name}\" for this {GetType().Name} transition.");
 
                 _prop = value;
             }
@@ -58,12 +44,13 @@ namespace Avalonia.Animation
         /// <summary>
         /// Apply interpolation to the property.
         /// </summary>
-        public abstract void DoInterpolation(Animatable control, IObservable<double> progress, T oldValue, T newValue);
+        public abstract IObservable<T> DoInterpolation(IObservable<double> progress, T oldValue, T newValue);
 
         /// <inheritdocs/>
-        public void Apply(Animatable control, object oldValue, object newValue)
+        public IDisposable Apply(Animatable control, object oldValue, object newValue)
         {
-            DoInterpolation(control, Timing.GetTimer(Duration), (T)oldValue, (T)newValue);
+            var transition = DoInterpolation(Timing.GetTimer(Duration), (T)oldValue, (T)newValue).Select(p => (object)p);
+            return control.Bind(Property, transition, Data.BindingPriority.Animation);
         }
 
     }

src/Avalonia.Controls/Presenters/CarouselPresenter.cs

@@ -39,7 +39,7 @@ namespace Avalonia.Controls.Presenters
             Carousel.PageTransitionProperty.AddOwner<CarouselPresenter>();
 
         private int _selectedIndex = -1;
-        private Task _current;
+       // private Task _current;
         private Task _currentTransition;
         private int _queuedTransitionIndex = -1;
 

src/Avalonia.Controls/ProgressBar.cs

@@ -105,8 +105,8 @@ namespace Avalonia.Controls
         private class IndeterminateAnimation : IDisposable
         {
             private WeakReference<ProgressBar> _progressBar;
-            private IDisposable _indeterminateBindSubscription;
-            private TimeSpan _startTime;
+            //private IDisposable _indeterminateBindSubscription;
+            //private TimeSpan _startTime;
             private bool _disposed;
 
             public bool Disposed => _disposed;
@@ -129,31 +129,31 @@ namespace Avalonia.Controls
 
             private Rect GetAnimationRect(TimeSpan time)
             {
-                if (_progressBar.TryGetTarget(out var progressBar))
-                {
-                    if (progressBar.Orientation == Orientation.Horizontal)
-                        return new Rect(-progressBar._indicator.Width - 5 + (time - _startTime).TotalSeconds / 4.0 * (progressBar.Bounds.Width + progressBar._indicator.Width + 10), 0, progressBar._indicator.Bounds.Width, progressBar._indicator.Bounds.Height);
-                    else
-                        return new Rect(0, progressBar.Bounds.Height + 5 - (time - _startTime).TotalSeconds / 4.0 * (progressBar.Bounds.Height + progressBar._indicator.Height + 10), progressBar._indicator.Bounds.Width, progressBar._indicator.Bounds.Height);
-                }
-                else
-                {
-                    _indeterminateBindSubscription.Dispose();
-                    return Rect.Empty;
-                }
+                //if (_progressBar.TryGetTarget(out var progressBar))
+                //{
+                //    if (progressBar.Orientation == Orientation.Horizontal)
+                //        return new Rect(-progressBar._indicator.Width - 5 + (time - _startTime).TotalSeconds / 4.0 * (progressBar.Bounds.Width + progressBar._indicator.Width + 10), 0, progressBar._indicator.Bounds.Width, progressBar._indicator.Bounds.Height);
+                //    else
+                //        return new Rect(0, progressBar.Bounds.Height + 5 - (time - _startTime).TotalSeconds / 4.0 * (progressBar.Bounds.Height + progressBar._indicator.Height + 10), progressBar._indicator.Bounds.Width, progressBar._indicator.Bounds.Height);
+                //}
+                //else
+                //{
+                //    _indeterminateBindSubscription.Dispose();
+                return Rect.Empty;
+                //}
             }
 
             private void AnimationTick(Rect rect)
             {
-                if (_progressBar.TryGetTarget(out var progressBar))
-                    progressBar._indicator.Arrange(rect);
-                else
-                    _indeterminateBindSubscription.Dispose();
+                //if (_progressBar.TryGetTarget(out var progressBar))
+                //    progressBar._indicator.Arrange(rect);
+                //else
+                //    _indeterminateBindSubscription.Dispose();
             }
 
             public void Dispose()
             {
-                _indeterminateBindSubscription?.Dispose();
+                //_indeterminateBindSubscription?.Dispose();
                 _disposed = true;
             }
         }

src/Avalonia.Visuals/Animation/CrossFade.cs

@@ -83,6 +83,9 @@ namespace Avalonia.Animation
 
             //await Task.WhenAll(tasks.ToArray());
 
+            // FIXME: This is temporary until animations are fixed.
+            await Task.Delay(1);
+
             if (from != null)
             {
                 from.IsVisible = false;

src/Avalonia.Visuals/Animation/PageSlide.cs

@@ -103,6 +103,9 @@ namespace Avalonia.Animation
 
             //await Task.WhenAll(tasks.ToArray());
 
+            // FIXME: This is temporary until animations are fixed.
+            await Task.Delay(1);
+
             if (from != null)
             {
                 from.IsVisible = false;