Merge pull request #12716 from Actipro/feat-transition-direct-props

Updated Transition to use direct properties via use of new TransitionBase class

src/Avalonia.Base/Animation/Transition.cs

@@ -1,53 +1,22 @@
 using System;
-using System.Diagnostics.CodeAnalysis;
-using Avalonia.Animation.Easings;
 
 namespace Avalonia.Animation
 {
     /// <summary>
     /// Defines how a property should be animated using a transition.
     /// </summary>
-    public abstract class Transition<T> : AvaloniaObject, ITransition
+    public abstract class Transition<T> : TransitionBase
     {
-        private AvaloniaProperty? _prop;
-
-        /// <summary>
-        /// Gets or sets the duration of the transition.
-        /// </summary> 
-        public TimeSpan Duration { get; set; }
-
-        /// <summary>
-        /// Gets or sets delay before starting the transition.
-        /// </summary> 
-        public TimeSpan Delay { get; set; } = TimeSpan.Zero;
-
-        /// <summary>
-        /// Gets the easing class to be used.
-        /// </summary>
-        public Easing Easing { get; set; } = new LinearEasing();
-
-        /// <inheritdocs/>
-        [DisallowNull]
-        public AvaloniaProperty? Property
+        static Transition()
         {
-            get
-            {
-                return _prop;
-            }
-            set
-            {
-                if (!(value.PropertyType.IsAssignableFrom(typeof(T))))
-                    throw new InvalidCastException
-                        ($"Invalid property type \"{typeof(T).Name}\" for this transition: {GetType().Name}.");
-
-                _prop = value;
-            }
+            PropertyProperty.Changed.AddClassHandler<Transition<T>>((x, e) => x.OnPropertyPropertyChanged(e));
         }
 
-        AvaloniaProperty ITransition.Property
+        private void OnPropertyPropertyChanged(AvaloniaPropertyChangedEventArgs e)
         {
-            get => Property ?? throw new InvalidOperationException("Transition has no property specified.");
-            set => Property = value;
+            if ((e.NewValue is AvaloniaProperty newValue) && !newValue.PropertyType.IsAssignableFrom(typeof(T)))
+                throw new InvalidCastException
+                    ($"Invalid property type \"{typeof(T).Name}\" for this transition: {GetType().Name}.");
         }
 
         /// <summary>
@@ -55,11 +24,7 @@ namespace Avalonia.Animation
         /// </summary>
         internal abstract IObservable<T> DoTransition(IObservable<double> progress, T oldValue, T newValue);
 
-        /// <inheritdocs/>
-        IDisposable ITransition.Apply(Animatable control, IClock clock, object? oldValue, object? newValue)
-            => Apply(control, clock, oldValue, newValue);
-        
-        internal virtual IDisposable Apply(Animatable control, IClock clock, object? oldValue, object? newValue)
+        internal override IDisposable Apply(Animatable control, IClock clock, object? oldValue, object? newValue)
         {
             if (Property is null)
                 throw new InvalidOperationException("Transition has no property specified.");

src/Avalonia.Base/Animation/TransitionBase.cs

@@ -0,0 +1,100 @@
+using System;
+using System.Diagnostics.CodeAnalysis;
+using Avalonia.Animation.Easings;
+
+namespace Avalonia.Animation
+{
+    /// <summary>
+    /// Defines how a property should be animated using a transition.
+    /// </summary>
+    public abstract class TransitionBase : AvaloniaObject, ITransition
+    {
+        /// <summary>
+        /// Defines the <see cref="Duration"/> property.
+        /// </summary>
+        public static readonly DirectProperty<TransitionBase, TimeSpan> DurationProperty =
+            AvaloniaProperty.RegisterDirect<TransitionBase, TimeSpan>(
+                nameof(Duration),
+                o => o._duration,
+                (o, v) => o._duration = v);
+        
+        /// <summary>
+        /// Defines the <see cref="Delay"/> property.
+        /// </summary>
+        public static readonly DirectProperty<TransitionBase, TimeSpan> DelayProperty =
+            AvaloniaProperty.RegisterDirect<TransitionBase, TimeSpan>(
+                nameof(Delay),
+                o => o._delay,
+                (o, v) => o._delay = v);
+        
+        /// <summary>
+        /// Defines the <see cref="Easing"/> property.
+        /// </summary>
+        public static readonly DirectProperty<TransitionBase, Easing> EasingProperty =
+            AvaloniaProperty.RegisterDirect<TransitionBase, Easing>(
+                nameof(Easing),
+                o => o._easing,
+                (o, v) => o._easing = v);
+        
+        /// <summary>
+        /// Defines the <see cref="Property"/> property.
+        /// </summary>
+        public static readonly DirectProperty<TransitionBase, AvaloniaProperty?> PropertyProperty =
+            AvaloniaProperty.RegisterDirect<TransitionBase, AvaloniaProperty?>(
+                nameof(Property),
+                o => o._prop,
+                (o, v) => o._prop = v);
+
+        private TimeSpan _duration;
+        private TimeSpan _delay = TimeSpan.Zero;
+        private Easing _easing = new LinearEasing();
+        private AvaloniaProperty? _prop;
+
+        /// <summary>
+        /// Gets or sets the duration of the transition.
+        /// </summary> 
+        public TimeSpan Duration
+        {
+            get { return _duration; }
+            set { SetAndRaise(DurationProperty, ref _duration, value); }
+        }
+
+        /// <summary>
+        /// Gets or sets delay before starting the transition.
+        /// </summary> 
+        public TimeSpan Delay
+        {
+            get { return _delay; }
+            set { SetAndRaise(DelayProperty, ref _delay, value); }
+        }
+
+        /// <summary>
+        /// Gets the easing class to be used.
+        /// </summary>
+        public Easing Easing
+        {
+            get { return _easing; }
+            set { SetAndRaise(EasingProperty, ref _easing, value); }
+        }
+
+        /// <inheritdocs/>
+        [DisallowNull]
+        public AvaloniaProperty? Property
+        {
+            get { return _prop; }
+            set { SetAndRaise(PropertyProperty, ref _prop, value); }
+        }
+
+        AvaloniaProperty ITransition.Property
+        {
+            get => Property ?? throw new InvalidOperationException("Transition has no property specified.");
+            set => Property = value;
+        }
+
+        /// <inheritdocs/>
+        IDisposable ITransition.Apply(Animatable control, IClock clock, object? oldValue, object? newValue)
+            => Apply(control, clock, oldValue, newValue);
+        
+        internal abstract IDisposable Apply(Animatable control, IClock clock, object? oldValue, object? newValue);
+    }
+}