Merge pull request #4183 from arcadiogarcia/user/arcadiog/clearReferenceInfo

Clear ReferenceNode ParamNames before serializing each expression string to avoid collisions

Author: michael-hawker

Microsoft.Toolkit.Uwp.UI.Animations/Expressions/CompositionExtensions.cs

@@ -176,6 +176,8 @@ public static void StartAnimation(this CompositionObject compObject, string prop
         /// <param name="easing">The easing function to use when interpolating between frames.</param>
         public static void InsertExpressionKeyFrame(this KeyFrameAnimation keyframeAnimation, float normalizedProgressKey, ExpressionNode expressionNode, CompositionEasingFunction easing = null)
         {
+            expressionNode.ClearReferenceInfo();
+
             keyframeAnimation.InsertExpressionKeyFrame(normalizedProgressKey, expressionNode.ToExpressionString(), easing);
 
             expressionNode.SetAllParameters(keyframeAnimation);
@@ -252,6 +254,7 @@ private static ExpressionAnimation CreateExpressionAnimationFromNode(Compositor
             // Only create a new animation if this node hasn't already generated one before, so we don't have to re-parse the expression string.
             if (expressionNode.ExpressionAnimation == null)
             {
+                expressionNode.ClearReferenceInfo();
                 expressionNode.ExpressionAnimation = compositor.CreateExpressionAnimation(expressionNode.ToExpressionString());
             }
 

Microsoft.Toolkit.Uwp.UI.Animations/Expressions/ExpressionNodes/ExpressionNode.cs

@@ -260,6 +260,20 @@ internal string ToExpressionString()
             return ToExpressionStringInternal();
         }
 
+        /// <summary>
+        /// Clears the reference information.
+        /// </summary>
+        /// <exception cref="System.Exception">Reference and paramName can't both be null</exception>
+        internal void ClearReferenceInfo()
+        {
+            _objRefList = null;
+            ParamName = null;
+            foreach (var child in Children)
+            {
+                child.ClearReferenceInfo();
+            }
+        }
+
         /// <summary>
         /// Ensures the reference information.
         /// </summary>