From 5c77a1de8c65430db6166a0eae174ee374ec9d3e Mon Sep 17 00:00:00 2001
From: Julien Lebosquain <julien@lebosquain.net>
Date: Tue, 8 Apr 2025 10:27:55 +0200
Subject: [PATCH] Fix Window.Show when MinWidth > MaxWidth (#18604)

* Add failing Window test

* Fix Window.Show when MinWidth > MaxWidth

* Fix AboutAvaloniaDialog size constraints
---
 src/Avalonia.Controls/Window.cs               | 10 ++++++----
 src/Avalonia.Dialogs/AboutAvaloniaDialog.xaml |  2 +-
 .../WindowTests.cs                            | 19 +++++++++++++++++++
 3 files changed, 26 insertions(+), 5 deletions(-)

diff --git a/src/Avalonia.Controls/Window.cs b/src/Avalonia.Controls/Window.cs
index c771cb2af0..6fb203b035 100644
--- a/src/Avalonia.Controls/Window.cs
+++ b/src/Avalonia.Controls/Window.cs
@@ -734,9 +734,11 @@ namespace Avalonia.Controls
                     double.IsNaN(Width) ? ClientSize.Width : Width,
                     double.IsNaN(Height) ? ClientSize.Height : Height);
 
+                var minMax = new MinMax(this);
+
                 initialSize = new Size(
-                MathUtilities.Clamp(initialSize.Width, MinWidth, MaxWidth),
-                MathUtilities.Clamp(initialSize.Height, MinHeight, MaxHeight));
+                    MathUtilities.Clamp(initialSize.Width, minMax.MinWidth, minMax.MaxWidth),
+                    MathUtilities.Clamp(initialSize.Height, minMax.MinHeight, minMax.MaxHeight));
 
                 var clientSizeChanged = initialSize != ClientSize;
                 ClientSize = initialSize; // ClientSize is required for Measure and Arrange
@@ -746,14 +748,14 @@ namespace Avalonia.Controls
 
                 if (SizeToContent.HasFlag(SizeToContent.Width))
                 {
-                    initialSize = initialSize.WithWidth(MathUtilities.Clamp(_arrangeBounds.Width, MinWidth, MaxWidth));
+                    initialSize = initialSize.WithWidth(MathUtilities.Clamp(_arrangeBounds.Width, minMax.MinWidth, minMax.MaxWidth));
                     clientSizeChanged |= initialSize != ClientSize;
                     ClientSize = initialSize;
                 }
 
                 if (SizeToContent.HasFlag(SizeToContent.Height))
                 {
-                    initialSize = initialSize.WithHeight(MathUtilities.Clamp(_arrangeBounds.Height, MinHeight, MaxHeight));
+                    initialSize = initialSize.WithHeight(MathUtilities.Clamp(_arrangeBounds.Height, minMax.MinHeight, minMax.MaxHeight));
                     clientSizeChanged |= initialSize != ClientSize;
                     ClientSize = initialSize;
                 }
diff --git a/src/Avalonia.Dialogs/AboutAvaloniaDialog.xaml b/src/Avalonia.Dialogs/AboutAvaloniaDialog.xaml
index b58df71ba2..e0bdf6d482 100644
--- a/src/Avalonia.Dialogs/AboutAvaloniaDialog.xaml
+++ b/src/Avalonia.Dialogs/AboutAvaloniaDialog.xaml
@@ -1,7 +1,7 @@
 <Window xmlns="https://github.com/avaloniaui"
         xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"
         xmlns:dialogs="using:Avalonia.Dialogs"
-        MaxWidth="400"
+        MaxWidth="430"
         MaxHeight="475"
         MinWidth="430"
         MinHeight="475"
diff --git a/tests/Avalonia.Controls.UnitTests/WindowTests.cs b/tests/Avalonia.Controls.UnitTests/WindowTests.cs
index 55b9a6de66..747608983b 100644
--- a/tests/Avalonia.Controls.UnitTests/WindowTests.cs
+++ b/tests/Avalonia.Controls.UnitTests/WindowTests.cs
@@ -1091,6 +1091,25 @@ namespace Avalonia.Controls.UnitTests
                     Assert.True(task.IsCompletedSuccessfully);
                 }
             }
+
+            [Fact]
+            public void Show_Works_When_Min_Dimension_Greater_Than_Max()
+            {
+                using var app = UnitTestApplication.Start(TestServices.StyledWindow);
+
+                var target = new Window
+                {
+                    MinWidth = 100,
+                    MaxWidth = 80,
+                    MinHeight = 200,
+                    MaxHeight = 180
+                };
+
+                Show(target);
+
+                Assert.Equal(100, target.Width);
+                Assert.Equal(200, target.Height);
+            }
             
             protected virtual void Show(Window window)
             {