From 310d594461463a0010f9cee4c65391cee2577be5 Mon Sep 17 00:00:00 2001
From: Steven Kirk <grokys@gmail.com>
Date: Thu, 14 May 2020 08:34:33 +0200
Subject: [PATCH] StackLayout incorrect sizing bug

Ported from https://github.com/microsoft/microsoft-ui-xaml/commit/c621498e61909850f1d7d0e760a296355f75d58f
---
 src/Avalonia.Layout/StackLayout.cs      | 4 ++--
 src/Avalonia.Layout/StackLayoutState.cs | 2 +-
 2 files changed, 3 insertions(+), 3 deletions(-)

diff --git a/src/Avalonia.Layout/StackLayout.cs b/src/Avalonia.Layout/StackLayout.cs
index b383c205f9..d11875b2c1 100644
--- a/src/Avalonia.Layout/StackLayout.cs
+++ b/src/Avalonia.Layout/StackLayout.cs
@@ -277,6 +277,8 @@ namespace Avalonia.Layout
 
         protected internal override Size MeasureOverride(VirtualizingLayoutContext context, Size availableSize)
         {
+            ((StackLayoutState)context.LayoutState).OnMeasureStart();
+
             var desiredSize = GetFlowAlgorithm(context).Measure(
                 availableSize,
                 context,
@@ -300,8 +302,6 @@ namespace Avalonia.Layout
                FlowLayoutAlgorithm.LineAlignment.Start,
                LayoutId);
 
-            ((StackLayoutState)context.LayoutState).OnArrangeLayoutEnd();
-
             return new Size(value.Width, value.Height);
         }
 
diff --git a/src/Avalonia.Layout/StackLayoutState.cs b/src/Avalonia.Layout/StackLayoutState.cs
index 05ad9bca8e..e6164e02e6 100644
--- a/src/Avalonia.Layout/StackLayoutState.cs
+++ b/src/Avalonia.Layout/StackLayoutState.cs
@@ -56,6 +56,6 @@ namespace Avalonia.Layout
             MaxArrangeBounds = Math.Max(MaxArrangeBounds, minorSize);
         }
 
-        internal void OnArrangeLayoutEnd() => MaxArrangeBounds = 0;
+        internal void OnMeasureStart() => MaxArrangeBounds = 0;
     }
 }