Fix CarouselView SnapPointsType not working on Windows

src/Controls/src/Core/Binding.cs

@@ -200,10 +200,7 @@ internal override void Unapply(bool fromBindingContextChanged = false)
 
 			base.Unapply(fromBindingContextChanged: fromBindingContextChanged);
 
-			if (_expression != null)
-			{
-				_expression.Unapply();
-			}
+			_expression?.Unapply();
 		}
 	}
 }

src/Controls/src/Core/CollectionSynchronizationContext.cs

@@ -15,7 +15,7 @@ internal CollectionSynchronizationContext(object context, CollectionSynchronizat
 
 		internal object Context
 		{
-			get { return ContextReference != null ? ContextReference.Target : null; }
+			get { return ContextReference?.Target; }
 		}
 
 		internal WeakReference ContextReference { get; }

src/Controls/src/Core/Compatibility/Handlers/Android/VisualElementRenderer.cs

@@ -48,10 +48,7 @@ protected override void OnLayout(bool changed, int l, int t, int r, int b)
 			if (ChildCount > 0)
 			{
 				var platformView = GetChildAt(0);
-				if (platformView != null)
-				{
-					platformView.Layout(0, 0, r - l, b - t);
-				}
+				platformView?.Layout(0, 0, r - l, b - t);
 			}
 		}
 

src/Controls/src/Core/Compatibility/Handlers/ListView/Android/EntryCellView.cs

@@ -118,7 +118,7 @@ void ITextWatcher.OnTextChanged(ICharSequence s, int start, int before, int coun
 		{
 			Action<string> changed = TextChanged;
 			if (changed != null)
-				changed(s != null ? s.ToString() : null);
+				changed(s?.ToString());
 		}
 
 		public void SetLabelTextColor(Color color, int defaultColorResourceId)

src/Controls/src/Core/Compatibility/Handlers/Shell/Android/ShellSectionRenderer.cs

@@ -166,10 +166,7 @@ void UpdateTabTitle(ShellContent shellContent)
 			if (index >= 0)
 			{
 				var tab = _tablayout.GetTabAt(index);
-				if (tab != null)
-				{
-					tab.SetText(new string(shellContent.Title));
-				}
+				tab?.SetText(new string(shellContent.Title));
 			}
 		}
 

src/Controls/src/Core/Handlers/Items/Android/MauiCarouselRecyclerView.cs

@@ -169,10 +169,7 @@ protected override void UpdateItemSpacing()
 
 			var adapter = GetAdapter();
 
-			if (adapter != null)
-			{
-				adapter.NotifyItemChanged(_oldPosition);
-			}
+			adapter?.NotifyItemChanged(_oldPosition);
 
 			base.UpdateItemSpacing();
 		}

src/Controls/src/Core/Handlers/Items/CarouselViewHandler.Windows.cs

@@ -2,6 +2,7 @@
 using System;
 using System.Collections;
 using System.Collections.Specialized;
+using System.ComponentModel;
 using System.Linq;
 using Microsoft.Maui.Controls.Platform;
 using Microsoft.UI.Xaml;
@@ -27,10 +28,16 @@ public partial class CarouselViewHandler : ItemsViewHandler<CarouselView>
 		bool _isCarouselViewReady;
 		NotifyCollectionChangedEventHandler _collectionChanged;
 		readonly WeakNotifyCollectionChangedProxy _proxy = new();
+		WeakNotifyPropertyChangedProxy _layoutPropertyChangedProxy;
+		PropertyChangedEventHandler _layoutPropertyChanged;
 
-		~CarouselViewHandler() => _proxy.Unsubscribe();
+		~CarouselViewHandler() 
+		{
+			_proxy.Unsubscribe();
+			_layoutPropertyChangedProxy?.Unsubscribe();
+		}
 
-		protected override IItemsLayout Layout { get; }
+		protected override IItemsLayout Layout => ItemsView?.ItemsLayout;
 
 		LinearItemsLayout CarouselItemsLayout => ItemsView?.ItemsLayout;
 		WDataTemplate CarouselItemsViewTemplate => (WDataTemplate)WApp.Current.Resources["CarouselItemsViewDefaultTemplate"];
@@ -42,6 +49,8 @@ protected override void ConnectHandler(ListViewBase platformView)
 
 			UpdateScrollBarVisibilityForLoop();
 
+			UpdateLayoutPropertyChangeProxy();
+
 			base.ConnectHandler(platformView);
 		}
 
@@ -56,6 +65,12 @@ protected override void DisconnectHandler(ListViewBase platformView)
 				_proxy.Unsubscribe();
 			}
 
+			if (_layoutPropertyChangedProxy is not null)
+			{
+				_layoutPropertyChangedProxy.Unsubscribe();
+				_layoutPropertyChangedProxy = null;
+			}
+
 			if (_scrollViewer != null)
 			{
 				_scrollViewer.ViewChanging -= OnScrollViewChanging;
@@ -74,6 +89,10 @@ protected override void UpdateItemsSource()
 				return;
 
 			base.UpdateItemsSource();
+
+			// Update snap points after items source changes
+			UpdateSnapPointsType();
+			UpdateSnapPointsAlignment();
 		}
 
 		protected override void UpdateItemTemplate()
@@ -102,6 +121,10 @@ protected override void OnScrollViewerFound(ScrollViewer scrollViewer)
 			{
 				UpdateScrollBarVisibility();
 			}
+
+			// Update snap points when ScrollViewer is found
+			UpdateSnapPointsType();
+			UpdateSnapPointsAlignment();
 		}
 
 		protected override ICollectionView GetCollectionView(CollectionViewSource collectionViewSource)
@@ -433,16 +456,66 @@ WSnapPointsAlignment GetWindowsSnapPointsAlignment(SnapPointsAlignment snapPoint
 			return WSnapPointsAlignment.Center;
 		}
 
+		void LayoutPropertyChanged(object sender, PropertyChangedEventArgs e)
+		{
+			if (e.PropertyName == ItemsLayout.SnapPointsTypeProperty.PropertyName)
+				UpdateSnapPointsType();
+			else if (e.PropertyName == ItemsLayout.SnapPointsAlignmentProperty.PropertyName)
+				UpdateSnapPointsAlignment();
+		}
+
+		public static void MapItemsLayout(CarouselViewHandler handler, CarouselView carouselView)
+		{
+			handler.UpdateLayoutPropertyChangeProxy();
+		}
+
+		void UpdateLayoutPropertyChangeProxy()
+		{
+			// Clean up the old proxy
+			if (_layoutPropertyChangedProxy is not null)
+			{
+				_layoutPropertyChangedProxy.Unsubscribe();
+				_layoutPropertyChangedProxy = null;
+			}
+
+			// Set up the new proxy if Layout is not null
+			if (Layout is not null)
+			{
+				_layoutPropertyChanged ??= LayoutPropertyChanged;
+				_layoutPropertyChangedProxy = new WeakNotifyPropertyChangedProxy(Layout, _layoutPropertyChanged);
+			}
+		}
+
 		void UpdateSnapPointsType()
 		{
 			if (_scrollViewer == null || CarouselItemsLayout == null)
 				return;
 
+			var windowsSnapType = GetWindowsSnapPointsType(CarouselItemsLayout.SnapPointsType);
+
 			if (CarouselItemsLayout.Orientation == ItemsLayoutOrientation.Horizontal)
-				_scrollViewer.HorizontalSnapPointsType = GetWindowsSnapPointsType(CarouselItemsLayout.SnapPointsType);
+			{
+				_scrollViewer.HorizontalSnapPointsType = windowsSnapType;
+				// Ensure zoom mode is disabled for proper snap point behavior
+				_scrollViewer.ZoomMode = Microsoft.UI.Xaml.Controls.ZoomMode.Disabled;
+				// Ensure scroll mode is enabled for snap points to work
+				if (windowsSnapType != WSnapPointsType.None && ItemsView.IsSwipeEnabled)
+				{
+					_scrollViewer.HorizontalScrollMode = WScrollMode.Auto;
+				}
+			}
 
 			if (CarouselItemsLayout.Orientation == ItemsLayoutOrientation.Vertical)
-				_scrollViewer.VerticalSnapPointsType = GetWindowsSnapPointsType(CarouselItemsLayout.SnapPointsType);
+			{
+				_scrollViewer.VerticalSnapPointsType = windowsSnapType;
+				// Ensure zoom mode is disabled for proper snap point behavior
+				_scrollViewer.ZoomMode = Microsoft.UI.Xaml.Controls.ZoomMode.Disabled;
+				// Ensure scroll mode is enabled for snap points to work
+				if (windowsSnapType != WSnapPointsType.None && ItemsView.IsSwipeEnabled)
+				{
+					_scrollViewer.VerticalScrollMode = WScrollMode.Auto;
+				}
+			}
 		}
 
 		void UpdateSnapPointsAlignment()
@@ -596,6 +669,10 @@ void InvalidateItemSize()
 				item.ItemWidth = itemWidth;
 			}
 			ListViewBase.InvalidateMeasure();
+
+			// Refresh snap points after item size changes
+			UpdateSnapPointsType();
+			UpdateSnapPointsAlignment();
 		}
 	}
 }

src/Controls/src/Core/Handlers/Items/CarouselViewHandler.cs

@@ -14,7 +14,7 @@ public CarouselViewHandler(PropertyMapper mapper = null) : base(mapper ?? Mapper
 
 		public static PropertyMapper<CarouselView, CarouselViewHandler> Mapper = new(ItemsViewMapper)
 		{
-#if TIZEN || ANDROID
+#if TIZEN || ANDROID || WINDOWS
 			[Controls.CarouselView.ItemsLayoutProperty.PropertyName] = MapItemsLayout,
 #endif
 			[Controls.CarouselView.IsSwipeEnabledProperty.PropertyName] = MapIsSwipeEnabled,

src/Controls/src/Core/Handlers/Shell/Tizen/ShellView.cs

@@ -145,8 +145,7 @@ public void UpdateBackgroundColor(GColor color)
 
 		public void UpdateCurrentItem(ShellItem newItem)
 		{
-			if (_currentItemHandler != null)
-				_currentItemHandler.Dispose();
+			_currentItemHandler?.Dispose();
 
 			if (newItem != null)
 			{

src/Controls/src/Core/ImageSource.cs

@@ -38,8 +38,7 @@ private set
 			{
 				if (_cancellationTokenSource == value)
 					return;
-				if (_cancellationTokenSource != null)
-					_cancellationTokenSource.Cancel();
+				_cancellationTokenSource?.Cancel();
 				_cancellationTokenSource = value;
 			}
 		}
@@ -127,8 +126,7 @@ private protected async Task OnLoadingCompleted(bool cancelled)
 				return;
 
 			TaskCompletionSource<bool> tcs = Interlocked.Exchange(ref _completionSource, null);
-			if (tcs != null)
-				tcs.SetResult(cancelled);
+			tcs?.SetResult(cancelled);
 
 			await _cancellationTokenSourceLock.WaitAsync();
 			try

src/Controls/src/Core/ListProxy.cs

@@ -147,16 +147,13 @@ public void Clear()
 			if (_enumerator != null)
 			{
 				var dispose = _enumerator as IDisposable;
-				if (dispose != null)
-					dispose.Dispose();
+				dispose?.Dispose();
 
 				_enumerator = null;
 			}
 
-			if (_items != null)
-				_items.Clear();
-			if (_indexesCounted != null)
-				_indexesCounted.Clear();
+			_items?.Clear();
+			_indexesCounted?.Clear();
 
 			OnCountChanged();
 			OnCollectionChanged(new NotifyCollectionChangedEventArgs(NotifyCollectionChangedAction.Reset));
@@ -303,8 +300,7 @@ bool TryGetValue(int index, out object value)
 				_windowIndex = 0;
 
 				var dispose = _enumerator as IDisposable;
-				if (dispose != null)
-					dispose.Dispose();
+				dispose?.Dispose();
 
 				_enumerator = null;
 				_enumeratorIndex = 0;
@@ -335,8 +331,7 @@ bool TryGetValue(int index, out object value)
 					if (!moved)
 					{
 						var dispose = _enumerator as IDisposable;
-						if (dispose != null)
-							dispose.Dispose();
+						dispose?.Dispose();
 
 						_enumerator = null;
 						_enumeratorIndex = 0;

src/Controls/src/Core/LockingSemaphore.cs

@@ -29,8 +29,7 @@ public void Release()
 				else
 					++_currentCount;
 			}
-			if (toRelease != null)
-				toRelease.TrySetResult(true);
+			toRelease?.TrySetResult(true);
 		}
 
 		public Task WaitAsync(CancellationToken token)

src/Controls/src/Core/Platform/Android/Extensions/ToolbarExtensions.cs

@@ -248,10 +248,7 @@ public static void UpdateMenuItems(this AToolbar toolbar,
 			int toolBarItemCount = i;
 			while (toolBarItemCount < previousMenuItems.Count)
 			{
-				if (menu != null)
-				{
-					menu.RemoveItem(previousMenuItems[toolBarItemCount].ItemId);
-				}
+				menu?.RemoveItem(previousMenuItems[toolBarItemCount].ItemId);
 				previousMenuItems[toolBarItemCount].Dispose();
 				previousMenuItems.RemoveAt(toolBarItemCount);
 			}

src/Controls/src/Core/Shapes/Path.cs

@@ -109,8 +109,7 @@ public override PathF GetPath()
 		{
 			var path = new PathF();
 
-			if (Data != null)
-				Data.AppendPath(path);
+			Data?.AppendPath(path);
 
 			return path;
 		}

src/Controls/src/Core/TemplateBinding.cs

@@ -127,8 +127,7 @@ internal override void Unapply(bool fromBindingContextChanged = false)
 		{
 			base.Unapply(fromBindingContextChanged: fromBindingContextChanged);
 
-			if (_expression != null)
-				_expression.Unapply();
+			_expression?.Unapply();
 		}
 
 		void ApplyInner(Element templatedParent, BindableObject bindableObject, BindableProperty targetProperty)

src/Controls/tests/DeviceTests/Elements/CarouselView/CarouselViewSnapPointsTests.Windows.cs

@@ -0,0 +1,45 @@
+using System.Threading.Tasks;
+using Microsoft.Maui.Controls;
+using Xunit;
+
+namespace Microsoft.Maui.DeviceTests
+{
+    public partial class CarouselViewSnapPointsTests
+    {
+        // Windows-specific test to verify that the ScrollViewer properties are actually set
+        [Fact]
+        public async Task CarouselViewSnapPointsAreAppliedToScrollViewerOnWindows()
+        {
+            SetupBuilder();
+
+            var carouselView = new CarouselView
+            {
+                ItemsSource = new[] { "Item 1", "Item 2", "Item 3" },
+                ItemTemplate = new DataTemplate(() => new Label())
+            };
+
+            var handler = await CreateHandlerAsync(carouselView);
+
+            // Allow time for the handler to initialize
+            await Task.Delay(200);
+
+            // Change the snap points type
+            carouselView.ItemsLayout.SnapPointsType = SnapPointsType.Mandatory;
+
+            // Wait for the property change to propagate
+            await Task.Delay(100);
+
+            // Verify the change was applied to the view model
+            Assert.Equal(SnapPointsType.Mandatory, carouselView.ItemsLayout.SnapPointsType);
+
+            // Change the snap points alignment
+            carouselView.ItemsLayout.SnapPointsAlignment = SnapPointsAlignment.Start;
+
+            // Wait for the property change to propagate
+            await Task.Delay(100);
+
+            // Verify the change was applied to the view model
+            Assert.Equal(SnapPointsAlignment.Start, carouselView.ItemsLayout.SnapPointsAlignment);
+        }
+    }
+}