Implement LayoutInformation.

src/Avalonia.Base/Layout/LayoutInformation.cs

@@ -0,0 +1,27 @@
+namespace Avalonia.Layout;
+
+/// <summary>
+/// Provides access to layout information of a control.
+/// </summary>
+public static class LayoutInformation
+{
+    /// <summary>
+    /// Gets the available size constraint passed in the previous layout pass.
+    /// </summary>
+    /// <param name="control">The control.</param>
+    /// <returns>Previous control measure constraint, if any.</returns>
+    public static Size? GetPreviousMeasureConstraint(Layoutable control)
+    {
+        return control.PreviousMeasure;
+    }
+
+    /// <summary>
+    /// Gets the control bounds used in the previous layout arrange pass.
+    /// </summary>
+    /// <param name="control">The control.</param>
+    /// <returns>Previous control arrange bounds, if any.</returns>
+    public static Rect? GetPreviousArrangeBounds(Layoutable control)
+    {
+        return control.PreviousArrange;
+    }
+}

src/Avalonia.Base/Layout/Layoutable.cs

@@ -326,12 +326,12 @@ namespace Avalonia.Layout
         /// <summary>
         /// Gets the available size passed in the previous layout pass, if any.
         /// </summary>
-        public Size? PreviousMeasure => _previousMeasure;
+        internal Size? PreviousMeasure => _previousMeasure;
 
         /// <summary>
         /// Gets the layout rect passed in the previous layout pass, if any.
         /// </summary>
-        public Rect? PreviousArrange => _previousArrange;
+        internal Rect? PreviousArrange => _previousArrange;
 
         /// <summary>
         /// Creates the visual children of the control, if necessary