From b2a78b269bb2937115453b2baca155892e3c68a1 Mon Sep 17 00:00:00 2001
From: Seungkeun Lee <sngn.lee@samsung.com>
Date: Fri, 8 Jun 2018 05:20:17 +0900
Subject: [PATCH] [Core] Fix Padding of Layout Issue (#2764) fixes #2763

---
 .../Issue2763.cs                              | 139 ++++++++++++++++++
 ...rin.Forms.Controls.Issues.Shared.projitems |   3 +-
 Xamarin.Forms.Core/Layout.cs                  |   2 +-
 3 files changed, 142 insertions(+), 2 deletions(-)
 create mode 100644 Xamarin.Forms.Controls.Issues/Xamarin.Forms.Controls.Issues.Shared/Issue2763.cs

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
new file mode 100644
index 000000000..35a9f9d01
--- /dev/null
+++ b/Xamarin.Forms.Controls.Issues/Xamarin.Forms.Controls.Issues.Shared/Issue2763.cs
@@ -0,0 +1,139 @@
+using Xamarin.Forms.CustomAttributes;
+using Xamarin.Forms.Internals;
+using Xamarin.Forms;
+
+namespace Xamarin.Forms.Controls
+{
+	// This test covers the issue reported in https://github.com/xamarin/Xamarin.Forms/issues/2763
+
+	[Preserve(AllMembers = true)]
+	[Issue(IssueTracker.Github, 2763,
+		"[Core] StakLayout Padding update issue", NavigationBehavior.PushAsync)]
+	public class Issue2763 : TestContentPage
+	{
+		protected override void Init()
+		{
+			StackLayout parentLayout1 = null;
+			StackLayout parentLayout2 = null;
+			StackLayout parentLayout3 = null;
+
+			StackLayout stackLayout = new StackLayout
+			{
+				HorizontalOptions = LayoutOptions.Center,
+				VerticalOptions = LayoutOptions.Center,
+				BackgroundColor = Color.Blue,
+				Children =
+				{
+					new BoxView
+					{
+						Color = Color.Red,
+						HeightRequest = 100,
+						WidthRequest = 100,
+					}
+				}
+			};
+
+			ContentView contentView = new ContentView
+			{
+				HorizontalOptions = LayoutOptions.Center,
+				VerticalOptions = LayoutOptions.Center,
+				BackgroundColor = Color.Blue,
+				Content =
+				new BoxView
+				{
+					Color = Color.Red,
+					HeightRequest = 100,
+					WidthRequest = 100,
+				}
+			};
+
+			FlexLayout flex = new FlexLayout
+			{
+				HorizontalOptions = LayoutOptions.Center,
+				VerticalOptions = LayoutOptions.Center,
+				BackgroundColor = Color.Blue,
+				Children =
+				{
+					new BoxView
+					{
+						Color = Color.Red,
+						HeightRequest = 100,
+						WidthRequest = 100,
+					}
+				}
+			};
+
+			Slider paddingSlider = new Slider
+			{
+				HorizontalOptions = LayoutOptions.FillAndExpand,
+				Minimum = 0.0,
+				Maximum = 100.0,
+			};
+
+			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 });
+
+			// Build the page.
+			this.Padding = new Thickness(20);
+			this.Content = new StackLayout
+			{
+				Spacing = 20,
+				Children =
+				{
+					new StackLayout
+					{
+						Orientation = StackOrientation.Horizontal,
+						Children =
+						{
+							new Label
+							{
+								Text = "Padding"
+							},
+							paddingSlider,
+						}
+					},
+					new Button()
+					{
+						Text = "Force update",
+						Command = new Command(() =>
+						{
+							var boxview = new BoxView();
+							parentLayout1.Children.Add(boxview);
+							parentLayout1.Children.Remove(boxview);
+							parentLayout2.Children.Add(boxview);
+							parentLayout2.Children.Remove(boxview);
+							parentLayout3.Children.Add(boxview);
+							parentLayout3.Children.Remove(boxview);
+						})
+					},
+					new ScrollView
+					{
+						HorizontalOptions = LayoutOptions.FillAndExpand,
+						VerticalOptions = LayoutOptions.FillAndExpand,
+						Content = new StackLayout
+						{
+							Spacing = 20,
+							Children =
+							{
+								(parentLayout1 = new StackLayout
+								{
+									Children = { new Label { Text = "StackLayout" }, stackLayout },
+								}),
+								(parentLayout2 = new StackLayout
+								{
+									Children = { new Label { Text = "ContentView" }, contentView }
+								}),
+								(parentLayout3 = new StackLayout
+								{
+									Children = { new Label { Text = "FlexLayout" }, flex }
+								})
+
+							}
+						}
+					}
+				}
+			};
+		}
+	}
+}
\ No newline at end of file
diff --git a/Xamarin.Forms.Controls.Issues/Xamarin.Forms.Controls.Issues.Shared/Xamarin.Forms.Controls.Issues.Shared.projitems b/Xamarin.Forms.Controls.Issues/Xamarin.Forms.Controls.Issues.Shared/Xamarin.Forms.Controls.Issues.Shared.projitems
index b51a96ea0..e94078fde 100644
--- a/Xamarin.Forms.Controls.Issues/Xamarin.Forms.Controls.Issues.Shared/Xamarin.Forms.Controls.Issues.Shared.projitems
+++ b/Xamarin.Forms.Controls.Issues/Xamarin.Forms.Controls.Issues.Shared/Xamarin.Forms.Controls.Issues.Shared.projitems
@@ -253,6 +253,7 @@
     <Compile Include="$(MSBuildThisFileDirectory)Issue1415.cs" />
     <Compile Include="$(MSBuildThisFileDirectory)Issue2653.cs" />
     <Compile Include="$(MSBuildThisFileDirectory)Issue1942.cs" />
+    <Compile Include="$(MSBuildThisFileDirectory)Issue2763.cs" />
     <Compile Include="$(MSBuildThisFileDirectory)Issue2247.cs" />
     <Compile Include="$(MSBuildThisFileDirectory)GroupListViewHeaderIndexOutOfRange.cs" />
     <Compile Include="$(MSBuildThisFileDirectory)Issue1760.cs" />
@@ -910,4 +911,4 @@
       <Generator>MSBuild:UpdateDesignTimeXaml</Generator>
     </EmbeddedResource>
   </ItemGroup>
-</Project>
\ No newline at end of file
+</Project>
diff --git a/Xamarin.Forms.Core/Layout.cs b/Xamarin.Forms.Core/Layout.cs
index da640aeba..69a9ec208 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)
 		{
-			UpdateChildrenLayout();
+			InvalidateMeasureInternal(InvalidationTrigger.MeasureChanged);
 		}
 
 		internal ObservableCollection<Element> InternalChildren { get; } = new ObservableCollection<Element>();