Move invalidation function to LayoutHelper.

src/Avalonia.Controls/TopLevel.cs

@@ -299,7 +299,7 @@ namespace Avalonia.Controls
         /// <param name="scaling">The window scaling.</param>
         protected virtual void HandleScalingChanged(double scaling)
         {
-            InvalidateSelfAndDescendantsMeasure();
+            LayoutHelper.InvalidateSelfAndChildrenMeasure(this);
         }
 
         /// <inheritdoc/>

src/Avalonia.Layout/LayoutHelper.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 Avalonia.VisualTree;
 
 namespace Avalonia.Layout
 {
@@ -61,5 +62,31 @@ namespace Avalonia.Layout
 
             return availableSize;
         }
+
+        /// <summary>
+        /// Invalidates measure for this instance and all visual children recursively.
+        /// </summary>
+        public static void InvalidateSelfAndChildrenMeasure(ILayoutable control)
+        {
+            void InnerInvalidateMeasure(IVisual target)
+            {
+                if (target is ILayoutable targetLayoutable)
+                {
+                    targetLayoutable.InvalidateMeasure();
+                }
+
+                var visualChildren = target.VisualChildren;
+                var visualChildrenCount = visualChildren.Count;
+
+                for (int i = 0; i < visualChildrenCount; i++)
+                {
+                    IVisual child = visualChildren[i];
+
+                    InnerInvalidateMeasure(child);
+                }
+            }
+
+            InnerInvalidateMeasure(control);
+        }
     }
 }

src/Avalonia.Layout/Layoutable.cs

@@ -692,36 +692,10 @@ namespace Avalonia.Layout
             return finalSize;
         }
 
-        /// <summary>
-        /// Invalidates measure for this instance and all visual children.
-        /// </summary>
-        protected void InvalidateSelfAndDescendantsMeasure()
-        {
-            void InnerInvalidateMeasure(IVisual target)
-            {
-                if (target is ILayoutable layoutable)
-                {
-                    layoutable.InvalidateMeasure();
-                }
-
-                var visualChildren = target.VisualChildren;
-                var visualChildrenCount = visualChildren.Count;
-
-                for (int i = 0; i < visualChildrenCount; i++)
-                {
-                    IVisual child = visualChildren[i];
-
-                    InnerInvalidateMeasure(child);
-                }
-            }
-
-            InnerInvalidateMeasure(this);
-        }
-
         /// <inheritdoc/>
         protected sealed override void OnVisualParentChanged(IVisual oldParent, IVisual newParent)
         {
-            InvalidateSelfAndDescendantsMeasure();
+            LayoutHelper.InvalidateSelfAndChildrenMeasure(this);
 
             base.OnVisualParentChanged(oldParent, newParent);
         }