[SR5] Fix footer resizing issue (#29064)

* Revert "[iOS] CollectionView footer sizing when source is empty in SR5 (#28971)"

* - fix header/footer sizing issue

* - add screenshots

* - set to cv1 because behavior currently differs

Author: PureWeen

src/Controls/src/Core/Handlers/Items/iOS/ItemsViewController.cs

@@ -199,12 +199,6 @@ public override void ViewWillAppear(bool animated)
 		public override void ViewWillLayoutSubviews()
 		{
 			ConstrainItemsToBounds();
-			
-			if (CollectionView is Items.MauiCollectionView { NeedsCellLayout: true } collectionView)
- 			{
- 				collectionView.NeedsCellLayout = false;
- 			}
-
 			base.ViewWillLayoutSubviews();
 			InvalidateMeasureIfContentSizeChanged();
 			LayoutEmptyView();

src/Controls/src/Core/Handlers/Items/iOS/MauiCollectionView.cs

@@ -10,9 +10,6 @@ internal class MauiCollectionView : UICollectionView, IUIViewLifeCycleEvents, IP
 	bool _invalidateParentWhenMovedToWindow;
 
 	WeakReference<ICustomMauiCollectionViewDelegate>? _customDelegate;
-
-	internal bool NeedsCellLayout { get; set; }
-	
 	public MauiCollectionView(CGRect frame, UICollectionViewLayout layout) : base(frame, layout)
 	{
 	}
@@ -30,11 +27,10 @@ void IPlatformMeasureInvalidationController.InvalidateAncestorsMeasuresWhenMoved
 
 	void IPlatformMeasureInvalidationController.InvalidateMeasure(bool isPropagating)
 	{
-		if (isPropagating)
+		if (!isPropagating)
 		{
-			NeedsCellLayout = true;
+			SetNeedsLayout();
 		}
-		SetNeedsLayout();
 	}
 
 	[UnconditionalSuppressMessage("Memory", "MEM0002", Justification = IUIViewLifeCycleEvents.UnconditionalSuppressMessage)]

src/Controls/src/Core/Handlers/Items/iOS/StructuredItemsViewController.cs

@@ -20,6 +20,7 @@ public class StructuredItemsViewController<TItemsView> : ItemsViewController<TIt
 
 		UIView _footerUIView;
 		VisualElement _footerViewFormsElement;
+		bool _headerFooterPositionNeedLayoutUpdate;
 
 		public StructuredItemsViewController(TItemsView structuredItemsView, ItemsViewLayout layout)
 			: base(structuredItemsView, layout)
@@ -86,23 +87,34 @@ protected override CGRect DetermineEmptyViewFrame()
 
 		public override void ViewWillLayoutSubviews()
 		{
-			var hasHeaderOrFooter = _footerViewFormsElement is not null || _headerViewFormsElement is not null;
-			if (hasHeaderOrFooter && CollectionView is MauiCollectionView { NeedsCellLayout: true } collectionView)
+			if (_headerFooterPositionNeedLayoutUpdate)
 			{
-				if (_headerViewFormsElement is not null)
+				UpdateHeaderFooterPosition();
+				base.ViewWillLayoutSubviews();
+			}
+			else
+			{
+				base.ViewWillLayoutSubviews();
+				// This update is only relevant if you have a footer view because it's used to place the footer view
+				// based on the ContentSize so we just update the positions if the ContentSize has changed
+				if (_footerUIView != null)
 				{
-					RemeasureLayout(_headerViewFormsElement);
-				}
+					var emptyView = CollectionView.ViewWithTag(EmptyTag);
 
-				if (_footerViewFormsElement is not null)
-				{
-					RemeasureLayout(_footerViewFormsElement);
+					if (IsHorizontal)
+					{
+						if (_footerUIView.Frame.X != ItemsViewLayout.CollectionViewContentSize.Width ||
+							_footerUIView.Frame.X < emptyView?.Frame.X)
+							UpdateHeaderFooterPosition();
+					}
+					else
+					{
+						if (_footerUIView.Frame.Y != ItemsViewLayout.CollectionViewContentSize.Height ||
+							_footerUIView.Frame.Y < (emptyView?.Frame.Y + emptyView?.Frame.Height))
+							UpdateHeaderFooterPosition();
+					}
 				}
-
-				UpdateHeaderFooterPosition();
 			}
-
-			base.ViewWillLayoutSubviews();
 		}
 
 		internal void UpdateFooterView()
@@ -154,8 +166,19 @@ internal void UpdateSubview(object view, DataTemplate viewTemplate, nint viewTag
 			}
 		}
 
+
 		void UpdateHeaderFooterPosition()
 		{
+			// The Frame values for `CollectionView` aren't valid until the `CollectionView` has been added to the window
+			// The initial frame is always just some default value that we will need to update once the CollectionView is added to the window
+			if (CollectionView?.Window is null)
+			{
+				_headerFooterPositionNeedLayoutUpdate = true;
+				return;
+			}
+
+			_headerFooterPositionNeedLayoutUpdate = false;
+
 			var emptyView = CollectionView.ViewWithTag(EmptyTag);
 
 			if (IsHorizontal)

src/Controls/tests/TestCases.Android.Tests/snapshots/android/FooterAndHeaderArePlacedCorrectlyAboveAndBelowCollectionView.png

@@ -0,0 +1,71 @@
+namespace Maui.Controls.Sample.Issues;
+[Issue(IssueTracker.Github, 29051, "I8_Headers_and_Footers displays the footer 2019 in the middle of the header", PlatformAffected.iOS)]
+public class Issue29051 : ContentPage
+{
+	public Issue29051()
+	{
+		var mainGrid = new Grid
+		{
+			Margin = new Thickness(20),
+			RowDefinitions =
+			{
+				new RowDefinition { Height = GridLength.Auto },
+				new RowDefinition { Height = GridLength.Star }
+			}
+		};
+
+		var instructionsStack = new StackLayout
+		{
+			Children =
+			{
+				new Label { Text = "1. The test passes if the view is displayed in Vertical list layout." },
+				new Label { Text = "2. The test passes if the header text display 'Monkeys'." },
+				new Label { Text = "3. The test passes if the footer text display '2019'." }
+			}
+		};
+
+		Grid.SetRow(instructionsStack, 0);
+		mainGrid.Children.Add(instructionsStack);
+
+		var collectionView = new CollectionView1
+		{
+			Header = "Monkeys",
+			Footer = "2019",
+			ItemTemplate = new DataTemplate(() =>
+			{
+				var itemGrid = new Grid
+				{
+					Padding = new Thickness(10),
+					RowDefinitions =
+					{
+						new RowDefinition { Height = GridLength.Auto },
+						new RowDefinition { Height = GridLength.Auto }
+					},
+					ColumnDefinitions =
+					{
+						new ColumnDefinition { Width = GridLength.Auto },
+						new ColumnDefinition { Width = GridLength.Star }
+					}
+				};
+
+				var nameLabel = new Label
+				{
+					FontAttributes = FontAttributes.Bold
+				};
+				nameLabel.SetBinding(Label.TextProperty, "Name");
+				nameLabel.SetBinding(Label.AutomationIdProperty, "AutomationId");
+
+				Grid.SetColumn(nameLabel, 1);
+				itemGrid.Children.Add(nameLabel);
+
+				return itemGrid;
+			}),
+			ItemsSource = Enumerable.Range(0, 5).Select(i => new { Name = $"Item {i}", AutomationId = $"Item{i}" }).ToList(),
+		};
+
+		Grid.SetRow(collectionView, 1);
+		mainGrid.Children.Add(collectionView);
+
+		Content = mainGrid;
+	}
+}

src/Controls/tests/TestCases.HostApp/Issues/Issue29051.cs

@@ -0,0 +1,21 @@
+using NUnit.Framework;
+using UITest.Appium;
+using UITest.Core;
+
+namespace Microsoft.Maui.TestCases.Tests.Issues;
+public class Issue29051 : _IssuesUITest
+{
+	public Issue29051(TestDevice testDevice) : base(testDevice)
+	{
+	}
+
+	public override string Issue => "I8_Headers_and_Footers displays the footer 2019 in the middle of the header";
+
+	[Test]
+	[Category(UITestCategories.CollectionView)]
+	public void FooterAndHeaderArePlacedCorrectlyAboveAndBelowCollectionView()
+	{
+		App.WaitForElement("Item1");
+		VerifyScreenshot();
+	}
+}