From c4a5567090357c49d0b69634406d6cb3195cd625 Mon Sep 17 00:00:00 2001
From: Steven Kirk <grokys@users.noreply.github.com>
Date: Fri, 28 Apr 2023 12:32:20 +0200
Subject: [PATCH 1/2] Added failing test for #11161.

---
 .../Layout/LayoutManagerTests.cs              | 33 +++++++++++++++++++
 .../Layout/LayoutTestControl.cs               | 32 ++++++++++++++----
 2 files changed, 59 insertions(+), 6 deletions(-)

diff --git a/tests/Avalonia.Base.UnitTests/Layout/LayoutManagerTests.cs b/tests/Avalonia.Base.UnitTests/Layout/LayoutManagerTests.cs
index 09f78c5a6c..45a6efdd4a 100644
--- a/tests/Avalonia.Base.UnitTests/Layout/LayoutManagerTests.cs
+++ b/tests/Avalonia.Base.UnitTests/Layout/LayoutManagerTests.cs
@@ -514,5 +514,38 @@ namespace Avalonia.Base.UnitTests.Layout
             Assert.True(parent.IsMeasureValid);
             Assert.True(parent.IsArrangeValid);
         }
+
+        [Fact]
+        public void Grandparent_Can_Invalidate_Root_Measure_During_Arrange()
+        {
+            // Issue #11161.
+            var child = new LayoutTestControl();
+            var parent = new LayoutTestControl { Child = child };
+            var grandparent = new LayoutTestControl { Child = parent };
+            var root = new LayoutTestRoot { Child = grandparent };
+
+            root.LayoutManager.ExecuteInitialLayoutPass();
+
+            grandparent.DoArrangeOverride = (_, s) =>
+            {
+                root.InvalidateMeasure();
+                return s;
+            };
+            grandparent.CallBaseArrange = true;
+
+            child.InvalidateMeasure();
+            grandparent.InvalidateMeasure();
+
+            root.LayoutManager.ExecuteLayoutPass();
+
+            Assert.True(child.IsMeasureValid);
+            Assert.True(child.IsArrangeValid);
+            Assert.True(parent.IsMeasureValid);
+            Assert.True(parent.IsArrangeValid);
+            Assert.True(grandparent.IsMeasureValid);
+            Assert.True(grandparent.IsArrangeValid);
+            Assert.True(root.IsMeasureValid);
+            Assert.True(root.IsArrangeValid);
+        }
     }
 }
diff --git a/tests/Avalonia.Base.UnitTests/Layout/LayoutTestControl.cs b/tests/Avalonia.Base.UnitTests/Layout/LayoutTestControl.cs
index 62de81006e..d85c7ed9bc 100644
--- a/tests/Avalonia.Base.UnitTests/Layout/LayoutTestControl.cs
+++ b/tests/Avalonia.Base.UnitTests/Layout/LayoutTestControl.cs
@@ -10,21 +10,41 @@ namespace Avalonia.Base.UnitTests.Layout
         public bool Arranged { get; set; }
         public Func<Layoutable, Size, Size> DoMeasureOverride { get; set; }
         public Func<Layoutable, Size, Size> DoArrangeOverride { get; set; }
+        public bool CallBaseMeasure { get; set; }
+        public bool CallBaseArrange { get; set; }
 
         protected override Size MeasureOverride(Size availableSize)
         {
             Measured = true;
-            return DoMeasureOverride != null ?
-                DoMeasureOverride(this, availableSize) :
-                base.MeasureOverride(availableSize);
+
+            if (DoMeasureOverride is not null)
+            {
+                var overrideResult = DoMeasureOverride(this, availableSize);
+                return CallBaseMeasure ?
+                    base.MeasureOverride(overrideResult) :
+                    overrideResult;
+            }
+            else
+            {
+                return base.MeasureOverride(availableSize);
+            }
         }
 
         protected override Size ArrangeOverride(Size finalSize)
         {
             Arranged = true;
-            return DoArrangeOverride != null ?
-                DoArrangeOverride(this, finalSize) :
-                base.ArrangeOverride(finalSize);
+
+            if (DoArrangeOverride is not null)
+            {
+                var overrideResult = DoArrangeOverride(this, finalSize);
+                return CallBaseArrange ?
+                    base.ArrangeOverride(overrideResult) :
+                    overrideResult;
+            }
+            else
+            {
+                return base.ArrangeOverride(finalSize);
+            }
         }
     }
 }

From a03b73a7347fe442e141ead2662328cf686f3eee Mon Sep 17 00:00:00 2001
From: Steven Kirk <grokys@users.noreply.github.com>
Date: Fri, 28 Apr 2023 13:02:37 +0200
Subject: [PATCH 2/2] Always add control in measure queue to arrange queue.

And also removed the checks for `IsAttachedToVisualTree`: that's going to be checked in `Arrange` and `Measure`.

Fixes #11161
---
 src/Avalonia.Base/Layout/LayoutManager.cs | 8 ++++----
 1 file changed, 4 insertions(+), 4 deletions(-)

diff --git a/src/Avalonia.Base/Layout/LayoutManager.cs b/src/Avalonia.Base/Layout/LayoutManager.cs
index 747ee1c082..f47738f2e4 100644
--- a/src/Avalonia.Base/Layout/LayoutManager.cs
+++ b/src/Avalonia.Base/Layout/LayoutManager.cs
@@ -249,10 +249,12 @@ namespace Avalonia.Layout
             {
                 var control = _toMeasure.Dequeue();
 
-                if (!control.IsMeasureValid && control.IsAttachedToVisualTree)
+                if (!control.IsMeasureValid)
                 {
                     Measure(control);
                 }
+
+                _toArrange.Enqueue(control);
             }
         }
 
@@ -262,7 +264,7 @@ namespace Avalonia.Layout
             {
                 var control = _toArrange.Dequeue();
 
-                if (!control.IsArrangeValid && control.IsAttachedToVisualTree)
+                if (!control.IsArrangeValid)
                 {
                     Arrange(control);
                 }
@@ -297,8 +299,6 @@ namespace Avalonia.Layout
                 {
                     control.Measure(control.PreviousMeasure.Value);
                 }
-
-                _toArrange.Enqueue(control);
             }
 
             return true;