From d5b622af62777f831d698cdf5ba37a3aad6221d0 Mon Sep 17 00:00:00 2001
From: Jerome Laban <jerome.laban@nventive.com>
Date: Wed, 5 May 2021 13:49:04 -0400
Subject: [PATCH] perf: Reduce foreach/linq usage in pointers management

Improves the performance of UIElement.Visibility changes
---
 src/Uno.UI/UI/Xaml/DependencyObjectExtensions.cs | 16 ++++++++++++++++
 src/Uno.UI/UI/Xaml/UIElement.PointerCapture.cs   |  2 +-
 src/Uno.UI/UI/Xaml/UIElement.Pointers.cs         | 12 +++++++++---
 3 files changed, 26 insertions(+), 4 deletions(-)

diff --git a/src/Uno.UI/UI/Xaml/DependencyObjectExtensions.cs b/src/Uno.UI/UI/Xaml/DependencyObjectExtensions.cs
index c5a30456e678..ffc951f38616 100644
--- a/src/Uno.UI/UI/Xaml/DependencyObjectExtensions.cs
+++ b/src/Uno.UI/UI/Xaml/DependencyObjectExtensions.cs
@@ -103,6 +103,22 @@ internal static IEnumerable<object> GetParents(this object dependencyObject)
 			}
 		}
 
+		internal static bool HasParent(this object dependencyObject, DependencyObject searchedParent)
+		{
+			var parent = dependencyObject.GetParent();
+			while (parent != null)
+			{
+				if(ReferenceEquals(parent, searchedParent))
+				{
+					return true;
+				}
+
+				parent = parent.GetParent();
+			}
+
+			return false;
+		}
+
 		/// <summary>
 		/// Set the parent of the specified dependency object
 		/// </summary>
diff --git a/src/Uno.UI/UI/Xaml/UIElement.PointerCapture.cs b/src/Uno.UI/UI/Xaml/UIElement.PointerCapture.cs
index 62bb5260bf50..d991d6fae4c7 100644
--- a/src/Uno.UI/UI/Xaml/UIElement.PointerCapture.cs
+++ b/src/Uno.UI/UI/Xaml/UIElement.PointerCapture.cs
@@ -46,7 +46,7 @@ public static PointerCapture GetOrCreate(Pointer pointer)
 			public static bool TryGet(Pointer pointer, out PointerCapture capture)
 				=> _actives.TryGetValue(pointer, out capture);
 
-			public static bool Any(out IEnumerable<PointerCapture> cloneOfAllCaptures)
+			public static bool Any(out List<PointerCapture> cloneOfAllCaptures)
 			{
 				if (_actives.Any())
 				{
diff --git a/src/Uno.UI/UI/Xaml/UIElement.Pointers.cs b/src/Uno.UI/UI/Xaml/UIElement.Pointers.cs
index 1b65d8619ad1..b6b0c90ad5ba 100644
--- a/src/Uno.UI/UI/Xaml/UIElement.Pointers.cs
+++ b/src/Uno.UI/UI/Xaml/UIElement.Pointers.cs
@@ -171,11 +171,17 @@ private void InitializePointers()
 				&& visibility != Visibility.Visible
 				&& PointerCapture.Any(out var captures))
 			{
-				foreach (var capture in captures)
+				for (var captureIndex = 0; captureIndex < captures.Count; captureIndex++)
 				{
-					foreach (var target in capture.Targets.ToList())
+					var capture = captures[captureIndex];
+
+					var targets = capture.Targets.ToList();
+
+					for (var targetIndex = 0; targetIndex < targets.Count; targetIndex++)
 					{
-						if (target.Element.GetParents().Contains(sender))
+						var target = targets[targetIndex];
+
+						if (target.Element.HasParent(sender))
 						{
 							target.Element.Release(capture, PointerCaptureKind.Any);
 						}