From 4f84e0741801c2c7a2b3fc5d545a536f3eee6a5c Mon Sep 17 00:00:00 2001
From: Jumar Macato <16554748+jmacato@users.noreply.github.com>
Date: Fri, 14 Feb 2020 17:39:14 +0800
Subject: [PATCH] Merge pull request #3570 from
 AvaloniaUI/fixes/3569-window-sizing

Fix window sizing
---
 src/Avalonia.Controls/Window.cs               |  2 +-
 .../WindowTests.cs                            | 51 +++++++++++++++++++
 2 files changed, 52 insertions(+), 1 deletion(-)

diff --git a/src/Avalonia.Controls/Window.cs b/src/Avalonia.Controls/Window.cs
index 0c37858223..6554237b3a 100644
--- a/src/Avalonia.Controls/Window.cs
+++ b/src/Avalonia.Controls/Window.cs
@@ -529,7 +529,7 @@ namespace Avalonia.Controls
         {
             var sizeToContent = SizeToContent;
             var clientSize = ClientSize;
-            Size constraint = clientSize;
+            var constraint = availableSize;
 
             if ((sizeToContent & SizeToContent.Width) != 0)
             {
diff --git a/tests/Avalonia.Controls.UnitTests/WindowTests.cs b/tests/Avalonia.Controls.UnitTests/WindowTests.cs
index 0508edd92f..81699b075c 100644
--- a/tests/Avalonia.Controls.UnitTests/WindowTests.cs
+++ b/tests/Avalonia.Controls.UnitTests/WindowTests.cs
@@ -341,11 +341,62 @@ namespace Avalonia.Controls.UnitTests
             }
         }
 
+        [Fact]
+        public void Child_Should_Be_Measured_With_Width_And_Height_If_SizeToContent_Is_Manual()
+        {
+            using (UnitTestApplication.Start(TestServices.StyledWindow))
+            {
+                var child = new ChildControl();
+                var target = new Window 
+                { 
+                    Width = 100,
+                    Height = 50,
+                    SizeToContent = SizeToContent.Manual,
+                    Content = child 
+                };
+
+                target.Show();
+
+                Assert.Equal(new Size(100, 50), child.MeasureSize);
+            }
+        }
+
+        [Fact]
+        public void Child_Should_Be_Measured_With_Infinity_If_SizeToContent_Is_WidthAndHeight()
+        {
+            using (UnitTestApplication.Start(TestServices.StyledWindow))
+            {
+                var child = new ChildControl();
+                var target = new Window
+                {
+                    Width = 100,
+                    Height = 50,
+                    SizeToContent = SizeToContent.WidthAndHeight,
+                    Content = child
+                };
+
+                target.Show();
+
+                Assert.Equal(Size.Infinity, child.MeasureSize);
+            }
+        }
+
         private IWindowImpl CreateImpl(Mock<IRenderer> renderer)
         {
             return Mock.Of<IWindowImpl>(x =>
                 x.Scaling == 1 &&
                 x.CreateRenderer(It.IsAny<IRenderRoot>()) == renderer.Object);
         }
+
+        private class ChildControl : Control
+        {
+            public Size MeasureSize { get; private set; }
+
+            protected override Size MeasureOverride(Size availableSize)
+            {
+                MeasureSize = availableSize;
+                return base.MeasureOverride(availableSize);
+            }
+        }
     }
 }