Fix memory leak in CollectionView and CarouselView by using instance-based ItemsLayout defaults

src/Controls/src/Core/Items/CarouselLayoutTypeConverter.cs

@@ -19,10 +19,10 @@ public override object ConvertFrom(ITypeDescriptorContext context, CultureInfo c
 			var strValue = value?.ToString();
 
 			if (strValue == "HorizontalList")
-				return LinearItemsLayout.CarouselDefault;
+				return LinearItemsLayout.CreateCarouselHorizontalDefault();
 
 			if (strValue == "VerticalList")
-				return LinearItemsLayout.CarouselVertical;
+				return LinearItemsLayout.CreateCarouselVerticalDefault();
 
 			throw new InvalidOperationException($"Cannot convert \"{strValue}\" into {typeof(LinearItemsLayout)}");
 		}

src/Controls/src/Core/Items/CarouselView.cs

@@ -187,7 +187,7 @@ public object PositionChangedCommandParameter
 		/// <summary>Bindable property for <see cref="ItemsLayout"/>.</summary>
 		public static readonly BindableProperty ItemsLayoutProperty =
 			BindableProperty.Create(nameof(ItemsLayout), typeof(LinearItemsLayout), typeof(ItemsView),
-				LinearItemsLayout.CarouselDefault);
+				null, defaultValueCreator: (b) => LinearItemsLayout.CreateCarouselHorizontalDefault());
 
 		/// <include file="../../../docs/Microsoft.Maui.Controls/CarouselView.xml" path="//Member[@MemberName='ItemsLayout']/Docs/*" />
 		[System.ComponentModel.TypeConverter(typeof(CarouselLayoutTypeConverter))]

src/Controls/src/Core/Items/ItemsLayoutTypeConverter.cs

@@ -24,9 +24,9 @@ public override object ConvertFrom(ITypeDescriptorContext context, CultureInfo c
 			int identifierLength = 0;
 
 			if (strValue == "VerticalList")
-				return LinearItemsLayout.Vertical;
+				return LinearItemsLayout.CreateVerticalDefault();
 			else if (strValue == "HorizontalList")
-				return LinearItemsLayout.Horizontal;
+				return LinearItemsLayout.CreateHorizontalDefault();
 			else if (strValue.StartsWith("VerticalGrid", StringComparison.Ordinal))
 			{
 				orientation = ItemsLayoutOrientation.Vertical;

src/Controls/src/Core/Items/ItemsView.cs

@@ -113,7 +113,8 @@ public int RemainingItemsThreshold
 
 		internal static readonly BindableProperty InternalItemsLayoutProperty =
 			BindableProperty.Create(nameof(ItemsLayout), typeof(IItemsLayout), typeof(ItemsView),
-				LinearItemsLayout.Vertical, propertyChanged: OnInternalItemsLayoutPropertyChanged);
+				null, propertyChanged: OnInternalItemsLayoutPropertyChanged, 
+				defaultValueCreator: (b) => LinearItemsLayout.CreateVerticalDefault());
 
 		static void OnInternalItemsLayoutPropertyChanged(BindableObject bindable, object oldValue, object newValue)
 		{

src/Controls/src/Core/Items/LinearItemsLayout.cs

@@ -12,22 +12,14 @@ public LinearItemsLayout([Parameter("Orientation")] ItemsLayoutOrientation orien
 		}
 
 		/// <include file="../../../docs/Microsoft.Maui.Controls/LinearItemsLayout.xml" path="//Member[@MemberName='Vertical']/Docs/*" />
-		public static readonly IItemsLayout Vertical = new LinearItemsLayout(ItemsLayoutOrientation.Vertical);
+		public static readonly IItemsLayout Vertical = CreateVerticalDefault();
 		/// <include file="../../../docs/Microsoft.Maui.Controls/LinearItemsLayout.xml" path="//Member[@MemberName='Horizontal']/Docs/*" />
-		public static readonly IItemsLayout Horizontal = new LinearItemsLayout(ItemsLayoutOrientation.Horizontal);
+		public static readonly IItemsLayout Horizontal = CreateHorizontalDefault();
 
 		/// <include file="../../../docs/Microsoft.Maui.Controls/LinearItemsLayout.xml" path="//Member[@MemberName='CarouselVertical']/Docs/*" />
-		public static readonly IItemsLayout CarouselVertical = new LinearItemsLayout(ItemsLayoutOrientation.Vertical)
-		{
-			SnapPointsType = SnapPointsType.MandatorySingle,
-			SnapPointsAlignment = SnapPointsAlignment.Center
-		};
+		public static readonly IItemsLayout CarouselVertical = CreateCarouselVerticalDefault();
 
-		internal static readonly LinearItemsLayout CarouselDefault = new LinearItemsLayout(ItemsLayoutOrientation.Horizontal)
-		{
-			SnapPointsType = SnapPointsType.MandatorySingle,
-			SnapPointsAlignment = SnapPointsAlignment.Center
-		};
+		internal static readonly LinearItemsLayout CarouselDefault = CreateCarouselHorizontalDefault();
 
 		/// <summary>Bindable property for <see cref="ItemSpacing"/>.</summary>
 		public static readonly BindableProperty ItemSpacingProperty =
@@ -40,5 +32,25 @@ public double ItemSpacing
 			get => (double)GetValue(ItemSpacingProperty);
 			set => SetValue(ItemSpacingProperty, value);
 		}
+
+		internal static LinearItemsLayout CreateVerticalDefault()
+			=> new LinearItemsLayout(ItemsLayoutOrientation.Vertical);
+
+		internal static LinearItemsLayout CreateHorizontalDefault()
+			=> new LinearItemsLayout(ItemsLayoutOrientation.Horizontal);
+
+		internal static LinearItemsLayout CreateCarouselVerticalDefault()
+			=> new LinearItemsLayout(ItemsLayoutOrientation.Vertical)
+			{
+				SnapPointsType = SnapPointsType.MandatorySingle,
+				SnapPointsAlignment = SnapPointsAlignment.Center
+			};
+
+		internal static LinearItemsLayout CreateCarouselHorizontalDefault()
+			=> new LinearItemsLayout(ItemsLayoutOrientation.Horizontal)
+			{
+				SnapPointsType = SnapPointsType.MandatorySingle,
+				SnapPointsAlignment = SnapPointsAlignment.Center
+			};
 	}
 }

src/Controls/tests/Core.UnitTests/ItemsLayoutTypeConverterTests.cs

@@ -11,15 +11,21 @@ public void HorizontalListShouldReturnLinearItemsLayout()
 		{
 			var converter = new ItemsLayoutTypeConverter();
 			var result = converter.ConvertFromInvariantString("HorizontalList");
-			Assert.Same(LinearItemsLayout.Horizontal, result);
+
+			Assert.IsType<LinearItemsLayout>(result);
+			var linearLayout = (LinearItemsLayout)result;
+			Assert.Equal(ItemsLayoutOrientation.Horizontal, linearLayout.Orientation);
 		}
 
 		[Fact]
 		public void VerticalListShouldReturnLinearItemsLayout()
 		{
 			var converter = new ItemsLayoutTypeConverter();
 			var result = converter.ConvertFromInvariantString("VerticalList");
-			Assert.Same(LinearItemsLayout.Vertical, result);
+
+			Assert.IsType<LinearItemsLayout>(result);
+			var linearLayout = (LinearItemsLayout)result;
+			Assert.Equal(ItemsLayoutOrientation.Vertical, linearLayout.Orientation);
 		}
 
 		[Fact]

src/Controls/tests/DeviceTests/Elements/CarouselView/CarouselViewTests.iOS.cs

@@ -1,7 +1,54 @@
-namespace Microsoft.Maui.DeviceTests
+using System;
+using System.Collections.Generic;
+using System.Threading.Tasks;
+using Microsoft.Maui.Controls;
+using Microsoft.Maui.Controls.Handlers.Items2;
+using Microsoft.Maui.Handlers;
+using Xunit;
+
+namespace Microsoft.Maui.DeviceTests
 {
 	public partial class CarouselViewTests
 	{
+		[Fact(DisplayName = "CarouselView Does Not Leak With Default ItemsLayout")]
+		public async Task CarouselViewDoesNotLeakWithDefaultItemsLayout()
+		{
+			SetupBuilder();
+
+			WeakReference weakCarouselView = null;
+			WeakReference weakHandler = null;
+
+			await InvokeOnMainThreadAsync(async () =>
+			{
+				var carouselView = new CarouselView
+				{
+					ItemsSource = new List<string> { "Item 1", "Item 2", "Item 3" },
+					ItemTemplate = new DataTemplate(() => new Label())
+					// Note: Not setting ItemsLayout - using the default
+				};
+
+				weakCarouselView = new WeakReference(carouselView);
+
+				var handler = await CreateHandlerAsync<CarouselViewHandler2>(carouselView);
+
+				// Verify handler is created
+				Assert.NotNull(handler);
+
+				// Store weak reference to the handler
+				weakHandler = new WeakReference(handler);
+
+				// Disconnect the handler
+				((IElementHandler)handler).DisconnectHandler();
+			});
+
+			// Force garbage collection
+			await AssertionExtensions.WaitForGC(weakCarouselView, weakHandler);
 
+			// Verify the CarouselView was collected
+			Assert.False(weakCarouselView.IsAlive, "CarouselView should have been garbage collected");
+
+			// Verify the handler was collected
+			Assert.False(weakHandler.IsAlive, "CarouselViewHandler2 should have been garbage collected");
+		}
 	}
 }

src/Controls/tests/DeviceTests/Elements/CollectionView/CollectionViewTests.iOS.cs

@@ -251,6 +251,47 @@ public void IndexPathValidTest()
 			Assert.False(source.IsIndexPathValid(invalidSection));
 		}
 
+		[Fact(DisplayName = "CollectionView Does Not Leak With Default ItemsLayout")]
+		public async Task CollectionViewDoesNotLeakWithDefaultItemsLayout()
+		{
+			SetupBuilder();
+
+			WeakReference weakCollectionView = null;
+			WeakReference weakHandler = null;
+
+			await InvokeOnMainThreadAsync(async () =>
+			{
+				var collectionView = new CollectionView
+				{
+					ItemsSource = new List<string> { "Item 1", "Item 2", "Item 3" },
+					ItemTemplate = new DataTemplate(() => new Label())
+					// Note: Not setting ItemsLayout - using the default
+				};
+
+				weakCollectionView = new WeakReference(collectionView);
+
+				var handler = await CreateHandlerAsync<CollectionViewHandler2>(collectionView);
+
+				// Verify handler is created
+				Assert.NotNull(handler);
+
+				// Store weak reference to the handler
+				weakHandler = new WeakReference(handler);
+
+				// Disconnect the handler
+				((IElementHandler)handler).DisconnectHandler();
+			});
+
+			// Force garbage collection
+			await AssertionExtensions.WaitForGC(weakCollectionView, weakHandler);
+
+			// Verify the CollectionView was collected
+			Assert.False(weakCollectionView.IsAlive, "CollectionView should have been garbage collected");
+
+			// Verify the handler was collected
+			Assert.False(weakHandler.IsAlive, "CollectionViewHandler2 should have been garbage collected");
+		}
+
 		/// <summary>
 		/// Simulates what a developer might do with a Page/View
 		/// </summary>