Merge pull request #1795 from jkoritzinsky/pagetransitions

Reimplement Page Transitions

src/Avalonia.Controls/Expander.cs

@@ -66,9 +66,7 @@ namespace Avalonia.Controls
 
         protected virtual void OnIsExpandedChanged(AvaloniaPropertyChangedEventArgs e)
         {
-            IVisual visualContent = Presenter;
-
-            if (Content != null && ContentTransition != null && visualContent != null)
+            if (Content != null && ContentTransition != null && Presenter is Visual visualContent)
             {
                 bool forward = ExpandDirection == ExpandDirection.Left ||
                                 ExpandDirection == ExpandDirection.Up;
@@ -87,4 +85,4 @@ namespace Avalonia.Controls
         private ExpandDirection _expandDirection;
         private bool _isExpanded;
     }
-}
+}

src/Avalonia.Visuals/Animation/CrossFade.cs

@@ -5,6 +5,7 @@ using System;
 using System.Collections.Generic;
 using System.Reactive.Threading.Tasks;
 using System.Threading.Tasks;
+using Avalonia.Styling;
 using Avalonia.VisualTree;
 
 namespace Avalonia.Animation
@@ -14,10 +15,14 @@ namespace Avalonia.Animation
     /// </summary>
     public class CrossFade : IPageTransition
     {
+        private Animation _fadeOutAnimation;
+        private Animation _fadeInAnimation;
+
         /// <summary>
         /// Initializes a new instance of the <see cref="CrossFade"/> class.
         /// </summary>
         public CrossFade()
+            :this(TimeSpan.Zero)
         {
         }
 
@@ -27,13 +32,51 @@ namespace Avalonia.Animation
         /// <param name="duration">The duration of the animation.</param>
         public CrossFade(TimeSpan duration)
         {
-            Duration = duration;
+            _fadeOutAnimation = new Animation
+            {
+                new KeyFrame
+                (
+                    new Setter
+                    {
+                        Property = Visual.OpacityProperty,
+                        Value = 0.0
+                    }
+                )
+                {
+                    Cue = new Cue(1.0)
+                }
+            };
+            _fadeInAnimation = new Animation
+            {
+                new KeyFrame
+                (
+                    new Setter
+                    {
+                        Property = Visual.OpacityProperty,
+                        Value = 0.0
+                    }
+                )
+                {
+                    Cue = new Cue(0.0)
+                }
+            };
+            _fadeOutAnimation.Duration = _fadeInAnimation.Duration = duration;
         }
 
         /// <summary>
         /// Gets the duration of the animation.
         /// </summary>
-        public TimeSpan Duration { get; set; }
+        public TimeSpan Duration
+        {
+            get
+            {
+                return _fadeOutAnimation.Duration;
+            }
+            set
+            {
+                _fadeOutAnimation.Duration = _fadeInAnimation.Duration = value;
+            }
+        }
 
         /// <summary>
         /// Starts the animation.
@@ -47,12 +90,10 @@ namespace Avalonia.Animation
         /// <returns>
         /// A <see cref="Task"/> that tracks the progress of the animation.
         /// </returns>
-        public async Task Start(IVisual from, IVisual to)
+        public async Task Start(Visual from, Visual to)
         {
             var tasks = new List<Task>();
 
-            // TODO: Implement relevant transition logic here (or discard this class)
-            // in favor of XAML based transition for pages
             if (to != null)
             {
                 to.Opacity = 0;
@@ -60,22 +101,21 @@ namespace Avalonia.Animation
 
             if (from != null)
             {
+                tasks.Add(_fadeOutAnimation.RunAsync(from));
             }
 
             if (to != null)
             {
-                to.Opacity = 0;
                 to.IsVisible = true;
+                tasks.Add(_fadeInAnimation.RunAsync(to));
 
             }
 
-            // FIXME: This is temporary until animations are fixed.
-            await Task.Delay(1);
+            await Task.WhenAll(tasks);
 
             if (from != null)
             {
                 from.IsVisible = false;
-                from.Opacity = 1;
             }
 
             if (to != null)
@@ -99,7 +139,7 @@ namespace Avalonia.Animation
         /// <returns>
         /// A <see cref="Task"/> that tracks the progress of the animation.
         /// </returns>
-        Task IPageTransition.Start(IVisual from, IVisual to, bool forward)
+        Task IPageTransition.Start(Visual from, Visual to, bool forward)
         {
             return Start(from, to);
         }

src/Avalonia.Visuals/Animation/IPageTransition.cs

@@ -26,6 +26,6 @@ namespace Avalonia.Animation
         /// <returns>
         /// A <see cref="Task"/> that tracks the progress of the animation.
         /// </returns>
-        Task Start(IVisual from, IVisual to, bool forward);
+        Task Start(Visual from, Visual to, bool forward);
     }
 }

src/Avalonia.Visuals/Animation/PageSlide.cs

@@ -6,6 +6,7 @@ using System.Collections.Generic;
 using System.Reactive.Threading.Tasks;
 using System.Threading.Tasks;
 using Avalonia.Media;
+using Avalonia.Styling;
 using Avalonia.VisualTree;
 
 namespace Avalonia.Animation
@@ -67,7 +68,7 @@ namespace Avalonia.Animation
         /// <returns>
         /// A <see cref="Task"/> that tracks the progress of the animation.
         /// </returns>
-        public async Task Start(IVisual from, IVisual to, bool forward)
+        public async Task Start(Visual from, Visual to, bool forward)
         {
             var tasks = new List<Task>();
             var parent = GetVisualParent(from, to);
@@ -79,16 +80,69 @@ namespace Avalonia.Animation
             // in favor of XAML based transition for pages
             if (from != null)
             {
-
+                var animation = new Animation
+                {
+                    new KeyFrame
+                    (
+                        new Setter
+                        {
+                            Property = translateProperty,
+                            Value = 0
+                        }
+                    )
+                    {
+                        Cue = new Cue(0.0)
+                    },
+                    new KeyFrame
+                    (
+                        new Setter
+                        {
+                            Property = translateProperty,
+                            Value = forward ? -distance : distance
+                        }
+                    )
+                    {
+                        Cue = new Cue(1.0)
+                    }
+                };
+                animation.Duration = Duration;
+                tasks.Add(animation.RunAsync(from));
             }
 
             if (to != null)
             {
-
+                to.IsVisible = true;
+                var animation = new Animation
+                {
+
+                    new KeyFrame
+                    (
+                        new Setter
+                        {
+                            Property = translateProperty,
+                            Value = forward ? -distance : distance
+                        }
+                    )
+                    {
+                        Cue = new Cue(0.0)
+                    },
+                    new KeyFrame
+                    (
+                        new Setter
+                        {
+                            Property = translateProperty,
+                            Value = 0
+                        }
+                    )
+                    {
+                        Cue = new Cue(1.0)
+                    },
+                };
+                animation.Duration = Duration;
+                tasks.Add(animation.RunAsync(to));
             }
 
-            // FIXME: This is temporary until animations are fixed.
-            await Task.Delay(1);
+            await Task.WhenAll(tasks);
 
             if (from != null)
             {