Merge pull request #11587 from AvaloniaUI/feature/some-changes-for-rc

Added InterpolatingTransitionBase

src/Avalonia.Base/Animation/InterpolatingTransitionBase.cs

@@ -0,0 +1,28 @@
+using System;
+using Avalonia.Animation.Animators;
+
+namespace Avalonia.Animation;
+
+/// <summary>
+/// The base class for user-defined transition that are doing simple value interpolation
+/// </summary>
+public abstract class InterpolatingTransitionBase<T> : Transition<T>
+{
+    class Animator : Animator<T>
+    {
+        private readonly InterpolatingTransitionBase<T> _parent;
+
+        public Animator(InterpolatingTransitionBase<T> parent)
+        {
+            _parent = parent;
+        }
+        
+        public override T Interpolate(double progress, T oldValue, T newValue) =>
+            _parent.Interpolate(progress, oldValue, newValue);
+    }
+    
+    protected abstract T Interpolate(double progress, T from, T to);
+    
+    internal override IObservable<T> DoTransition(IObservable<double> progress, T oldValue, T newValue) =>
+        new AnimatorTransitionObservable<T, Animator>(new Animator(this), progress, Easing, oldValue, newValue);
+}