From 91c280a0144eb536c2f4a16aff69d45e1a3a34b5 Mon Sep 17 00:00:00 2001
From: Steven Kirk <grokys@gmail.com>
Date: Mon, 1 Jun 2020 16:03:25 +0200
Subject: [PATCH] Don't invalidate if viewport unchanged.

---
 src/Avalonia.Controls/Repeater/ViewportManager.cs | 6 +++++-
 1 file changed, 5 insertions(+), 1 deletion(-)

diff --git a/src/Avalonia.Controls/Repeater/ViewportManager.cs b/src/Avalonia.Controls/Repeater/ViewportManager.cs
index c62d447c95..e50de87877 100644
--- a/src/Avalonia.Controls/Repeater/ViewportManager.cs
+++ b/src/Avalonia.Controls/Repeater/ViewportManager.cs
@@ -459,6 +459,7 @@ namespace Avalonia.Controls
         private void UpdateViewport(Rect viewport)
         {
             var currentVisibleWindow = viewport;
+            var oldVisibleWindow = _visibleWindow;
 
             if (-currentVisibleWindow.X <= ItemsRepeater.ClearedElementsArrangePosition.X &&
                 -currentVisibleWindow.Y <= ItemsRepeater.ClearedElementsArrangePosition.Y)
@@ -471,7 +472,10 @@ namespace Avalonia.Controls
                 _visibleWindow = currentVisibleWindow;
             }
 
-            TryInvalidateMeasure();
+            if (_visibleWindow != oldVisibleWindow)
+            {
+                TryInvalidateMeasure();
+            }
         }
 
         private static void ValidateCacheLength(double cacheLength)