Added AvaloniaObject.IsAnimating(property).

Added a method to test whether a property on an object is currently animating.

src/Avalonia.Base/AvaloniaObject.cs

@@ -225,6 +225,19 @@ namespace Avalonia
             return (T)GetValue((AvaloniaProperty)property);
         }
 
+        /// <summary>
+        /// Checks whether a <see cref="AvaloniaProperty"/> is animating.
+        /// </summary>
+        /// <param name="property">The property.</param>
+        /// <returns>True if the property is animating, otherwise false.</returns>
+        public bool IsAnimating(AvaloniaProperty property)
+        {
+            Contract.Requires<ArgumentNullException>(property != null);
+            VerifyAccess();
+
+            return _values.TryGetValue(property, out PriorityValue value) ? value.IsAnimating : false;
+        }
+
         /// <summary>
         /// Checks whether a <see cref="AvaloniaProperty"/> is set on this object.
         /// </summary>

src/Avalonia.Base/IAvaloniaObject.cs

@@ -31,6 +31,13 @@ namespace Avalonia
         /// <returns>The value.</returns>
         T GetValue<T>(AvaloniaProperty<T> property);
 
+        /// <summary>
+        /// Checks whether a <see cref="AvaloniaProperty"/> is animating.
+        /// </summary>
+        /// <param name="property">The property.</param>
+        /// <returns>True if the property is animating, otherwise false.</returns>
+        bool IsAnimating(AvaloniaProperty property);
+
         /// <summary>
         /// Checks whether a <see cref="AvaloniaProperty"/> is set on this object.
         /// </summary>

src/Avalonia.Base/PriorityValue.cs

@@ -52,6 +52,8 @@ namespace Avalonia
             _validate = validate;
         }
 
+        public bool IsAnimating => ValuePriority < 0 && GetLevel(ValuePriority).ActiveBindingIndex != -1;
+
         /// <summary>
         /// Gets the owner of the value.
         /// </summary>

tests/Avalonia.Base.UnitTests/AvaloniaObjectTests_Binding.cs

@@ -387,6 +387,46 @@ namespace Avalonia.Base.UnitTests
             }
         }
 
+        [Fact]
+        public void IsAnimating_On_Property_With_No_Value_Returns_False()
+        {
+            var target = new Class1();
+
+            Assert.False(target.IsAnimating(Class1.FooProperty));
+        }
+
+        [Fact]
+        public void IsAnimating_On_Property_With_Animation_Value_Returns_False()
+        {
+            var target = new Class1();
+
+            target.SetValue(Class1.FooProperty, "foo", BindingPriority.Animation);
+
+            Assert.False(target.IsAnimating(Class1.FooProperty));
+        }
+
+        [Fact]
+        public void IsAnimating_On_Property_With_Non_Animation_Binding_Returns_False()
+        {
+            var target = new Class1();
+            var source = new Subject<string>();
+
+            target.Bind(Class1.FooProperty, source, BindingPriority.LocalValue);
+
+            Assert.False(target.IsAnimating(Class1.FooProperty));
+        }
+
+        [Fact]
+        public void IsAnimating_On_Property_With_Animation_Binding_Returns_True()
+        {
+            var target = new Class1();
+            var source = new BehaviorSubject<string>("foo");
+
+            target.Bind(Class1.FooProperty, source, BindingPriority.Animation);
+
+            Assert.True(target.IsAnimating(Class1.FooProperty));
+        }
+
         /// <summary>
         /// Returns an observable that returns a single value but does not complete.
         /// </summary>

tests/Avalonia.Base.UnitTests/DirectPropertyTests.cs

@@ -2,6 +2,7 @@
 // Licensed under the MIT license. See licence.md file in the project root for full license information.
 
 using System;
+using System.Reactive.Subjects;
 using Avalonia.Data;
 using Xunit;
 
@@ -70,6 +71,17 @@ namespace Avalonia.Base.UnitTests
             Assert.Same(p1.Initialized, p2.Initialized);
         }
 
+        [Fact]
+        public void IsAnimating_On_DirectProperty_With_Binding_Returns_False()
+        {
+            var target = new Class1();
+            var source = new BehaviorSubject<string>("foo");
+
+            target.Bind(Class1.FooProperty, source, BindingPriority.Animation);
+
+            Assert.False(target.IsAnimating(Class1.FooProperty));
+        }
+
         private class Class1 : AvaloniaObject
         {
             public static readonly DirectProperty<Class1, string> FooProperty =

tests/Avalonia.Styling.UnitTests/SelectorTests_Child.cs

@@ -135,6 +135,11 @@ namespace Avalonia.Styling.UnitTests
                 throw new NotImplementedException();
             }
 
+            public bool IsAnimating(AvaloniaProperty property)
+            {
+                throw new NotImplementedException();
+            }
+
             public bool IsSet(AvaloniaProperty property)
             {
                 throw new NotImplementedException();

tests/Avalonia.Styling.UnitTests/SelectorTests_Descendent.cs

@@ -165,6 +165,11 @@ namespace Avalonia.Styling.UnitTests
                 throw new NotImplementedException();
             }
 
+            public bool IsAnimating(AvaloniaProperty property)
+            {
+                throw new NotImplementedException();
+            }
+
             public bool IsSet(AvaloniaProperty property)
             {
                 throw new NotImplementedException();

tests/Avalonia.Styling.UnitTests/TestControlBase.cs

@@ -59,6 +59,11 @@ namespace Avalonia.Styling.UnitTests
             throw new NotImplementedException();
         }
 
+        public bool IsAnimating(AvaloniaProperty property)
+        {
+            throw new NotImplementedException();
+        }
+
         public bool IsSet(AvaloniaProperty property)
         {
             throw new NotImplementedException();

tests/Avalonia.Styling.UnitTests/TestTemplatedControl.cs

@@ -67,6 +67,11 @@ namespace Avalonia.Styling.UnitTests
             throw new NotImplementedException();
         }
 
+        public bool IsAnimating(AvaloniaProperty property)
+        {
+            throw new NotImplementedException();
+        }
+
         public bool IsSet(AvaloniaProperty property)
         {
             throw new NotImplementedException();