From 2eff1bb43d679a9fe21a9019bce2827cc28ebff8 Mon Sep 17 00:00:00 2001
From: Seungkeun Lee <sngn.lee@samsung.com>
Date: Fri, 26 Oct 2018 15:59:14 +0900
Subject: [PATCH] [Core] Fix layout padding update issue (#4166)

- Update PaddingPropertyChanged handler
 - Add UnitTest for Padding
 - Update ControlGallery

- fixes #4165
---
 .../Issue2763.cs                                   | 26 +++++++++
 .../StackLayoutUnitTests.cs                        | 68 ++++++++++++++++++++++
 Xamarin.Forms.Core/Layout.cs                       |  2 +-
 3 files changed, 95 insertions(+), 1 deletion(-)

diff --git a/Xamarin.Forms.Controls.Issues/Xamarin.Forms.Controls.Issues.Shared/Issue2763.cs b/Xamarin.Forms.Controls.Issues/Xamarin.Forms.Controls.Issues.Shared/Issue2763.cs
index 35a9f9d..d6e21fa 100644
--- a/Xamarin.Forms.Controls.Issues/Xamarin.Forms.Controls.Issues.Shared/Issue2763.cs
+++ b/Xamarin.Forms.Controls.Issues/Xamarin.Forms.Controls.Issues.Shared/Issue2763.cs
@@ -13,9 +13,11 @@ namespace Xamarin.Forms.Controls
 	{
 		protected override void Init()
 		{
+			Title = "Padding update issue";
 			StackLayout parentLayout1 = null;
 			StackLayout parentLayout2 = null;
 			StackLayout parentLayout3 = null;
+			StackLayout parentLayout4 = null;
 
 			StackLayout stackLayout = new StackLayout
 			{
@@ -32,6 +34,22 @@ namespace Xamarin.Forms.Controls
 					}
 				}
 			};
+			StackLayout stackLayout2 = new StackLayout
+			{
+				HorizontalOptions = LayoutOptions.FillAndExpand,
+				VerticalOptions = LayoutOptions.FillAndExpand,
+				BackgroundColor = Color.Blue,
+				Children =
+				{
+					new BoxView
+					{
+						HorizontalOptions = LayoutOptions.Start,
+						Color = Color.Red,
+						HeightRequest = 100,
+						WidthRequest = 100,
+					}
+				}
+			};
 
 			ContentView contentView = new ContentView
 			{
@@ -73,6 +91,7 @@ namespace Xamarin.Forms.Controls
 			stackLayout.SetBinding(Forms.Layout.PaddingProperty, new Binding() { Path = "Value", Source = paddingSlider });
 			contentView.SetBinding(Forms.Layout.PaddingProperty, new Binding() { Path = "Value", Source = paddingSlider });
 			flex.SetBinding(Forms.Layout.PaddingProperty, new Binding() { Path = "Value", Source = paddingSlider });
+			stackLayout2.SetBinding(Forms.Layout.PaddingProperty, new Binding() { Path = "Value", Source = paddingSlider });
 
 			// Build the page.
 			this.Padding = new Thickness(20);
@@ -105,6 +124,8 @@ namespace Xamarin.Forms.Controls
 							parentLayout2.Children.Remove(boxview);
 							parentLayout3.Children.Add(boxview);
 							parentLayout3.Children.Remove(boxview);
+							parentLayout4.Children.Add(boxview);
+							parentLayout4.Children.Remove(boxview);
 						})
 					},
 					new ScrollView
@@ -116,6 +137,11 @@ namespace Xamarin.Forms.Controls
 							Spacing = 20,
 							Children =
 							{
+								(parentLayout4 = new StackLayout
+								{
+									HeightRequest = 200,
+									Children = { new Label { Text = "StackLayout2" }, stackLayout2 },
+								}),
 								(parentLayout1 = new StackLayout
 								{
 									Children = { new Label { Text = "StackLayout" }, stackLayout },
diff --git a/Xamarin.Forms.Core.UnitTests/StackLayoutUnitTests.cs b/Xamarin.Forms.Core.UnitTests/StackLayoutUnitTests.cs
index fb4a8aa..1c91e10 100644
--- a/Xamarin.Forms.Core.UnitTests/StackLayoutUnitTests.cs
+++ b/Xamarin.Forms.Core.UnitTests/StackLayoutUnitTests.cs
@@ -615,5 +615,73 @@ namespace Xamarin.Forms.Core.UnitTests
 
 			stack.Layout (new Rectangle (0, 0, 100, 100));
 		}
+
+		[Test]
+		public void PaddingResizeTest()
+		{
+			var child = new BoxView
+			{
+				IsPlatformEnabled = true,
+				WidthRequest = 20,
+				HeightRequest = 20,
+			};
+
+			var innerStack = new StackLayout
+			{
+				HorizontalOptions = LayoutOptions.Center,
+				VerticalOptions = LayoutOptions.Center,
+				IsPlatformEnabled = true,
+				Children = { child }
+			};
+
+			var outterLayout = new StackLayout
+			{
+				HorizontalOptions = LayoutOptions.FillAndExpand,
+				VerticalOptions = LayoutOptions.FillAndExpand,
+				IsPlatformEnabled = true,
+				Platform = new UnitPlatform(),
+				Children = { innerStack }
+			};
+
+			outterLayout.Layout(new Rectangle(0, 0, 100, 100));
+			var beforeSize = innerStack.Bounds.Size;
+			innerStack.Padding = new Thickness(30);
+			var afterSize = innerStack.Bounds.Size;
+			Assert.AreNotEqual(beforeSize, afterSize, "Padding was grow, so Size should be bigger");
+		}
+
+		[Test]
+		public void PaddingChildRelayoutTest()
+		{
+			var child = new BoxView
+			{
+				IsPlatformEnabled = true,
+				WidthRequest = 20,
+				HeightRequest = 20,
+			};
+
+			var innerStack = new StackLayout
+			{
+				HorizontalOptions = LayoutOptions.FillAndExpand,
+				VerticalOptions = LayoutOptions.FillAndExpand,
+				IsPlatformEnabled = true,
+				Children = { child }
+			};
+
+			var outterLayout = new StackLayout
+			{
+				HorizontalOptions = LayoutOptions.FillAndExpand,
+				VerticalOptions = LayoutOptions.FillAndExpand,
+				IsPlatformEnabled = true,
+				Platform = new UnitPlatform(),
+				Children = { innerStack }
+			};
+
+			outterLayout.Layout(new Rectangle(0, 0, 100, 100));
+			var before = child.Bounds;
+			innerStack.Padding = new Thickness(30);
+			var after = child.Bounds;
+			Assert.AreNotEqual(before, after, "child should be moved within padding size");
+		}
 	}
 }
diff --git a/Xamarin.Forms.Core/Layout.cs b/Xamarin.Forms.Core/Layout.cs
index 4d1c8f7..d88e6cd 100644
--- a/Xamarin.Forms.Core/Layout.cs
+++ b/Xamarin.Forms.Core/Layout.cs
@@ -102,7 +102,7 @@ namespace Xamarin.Forms
 
 		void IPaddingElement.OnPaddingPropertyChanged(Thickness oldValue, Thickness newValue)
 		{
-			InvalidateMeasureInternal(InvalidationTrigger.MeasureChanged);
+			InvalidateLayout();
 		}
 
 		internal ObservableCollection<Element> InternalChildren { get; } = new ObservableCollection<Element>();
-- 
2.7.4