CarouselView: Fix cascading PositionChanged/CurrentItemChanged events on collection update

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

@@ -18,6 +18,7 @@ public class MauiCarouselRecyclerView : MauiRecyclerView<CarouselView, ItemsView
 		bool _initialized;
 		bool _isVisible;
 		bool _disposed;
+		bool _isInternalPositionUpdate;
 
 		List<View> _oldViews;
 		CarouselViewOnGlobalLayoutListener _carouselViewLayoutListener;
@@ -221,6 +222,9 @@ void CollectionItemsSourceChanged(object sender, System.Collections.Specialized.
 			if (!(ItemsViewAdapter.ItemsSource is IItemsViewSource observableItemsSource))
 				return;
 
+			// Set flag to disable animation during collection changes
+			_isInternalPositionUpdate = true;
+
 			var carouselPosition = Carousel.Position;
 			var currentItemPosition = observableItemsSource.GetPosition(Carousel.CurrentItem);
 			var count = observableItemsSource.Count;
@@ -265,6 +269,7 @@ void CollectionItemsSourceChanged(object sender, System.Collections.Specialized.
 
 			if (removingAnyPrevious)
 			{
+				_isInternalPositionUpdate = false;
 				return;
 			}
 
@@ -308,6 +313,9 @@ void CollectionItemsSourceChanged(object sender, System.Collections.Specialized.
 						}
 
 						UpdateVisualStates();
+
+						// Reset flag after collection operations complete
+						_isInternalPositionUpdate = false;
 					});
 		}
 
@@ -507,7 +515,7 @@ void IMauiCarouselRecyclerView.UpdateFromCurrentItem()
 			if (_gotoPosition == -1 && currentItemPosition != carouselPosition)
 			{
 				_gotoPosition = currentItemPosition;
-				ItemsView.ScrollTo(currentItemPosition, position: Microsoft.Maui.Controls.ScrollToPosition.Center, animate: Carousel.AnimateCurrentItemChanges);
+				ScrollToItemPosition(currentItemPosition, Carousel.AnimateCurrentItemChanges);
 			}
 
 			_gotoPosition = -1;
@@ -547,12 +555,18 @@ void IMauiCarouselRecyclerView.UpdateFromPosition()
 			if (_gotoPosition == -1 && !Carousel.IsDragging && !Carousel.IsScrolling && centerPosition != carouselPosition)
 			{
 				_gotoPosition = carouselPosition;
-
-				ItemsView.ScrollTo(carouselPosition, position: Microsoft.Maui.Controls.ScrollToPosition.Center, animate: Carousel.AnimatePositionChanges);
+				ScrollToItemPosition(carouselPosition, Carousel.AnimatePositionChanges);
 			}
 			SetCurrentItem(carouselPosition);
 		}
 
+		void ScrollToItemPosition(int position, bool shouldAnimate)
+		{
+			// Disable animation during collection changes to prevent cascading scroll events
+			var animate = shouldAnimate && !_isInternalPositionUpdate;
+			ItemsView.ScrollTo(position, position: Microsoft.Maui.Controls.ScrollToPosition.Center, animate: animate);
+		}
+
 		void AddLayoutListener()
 		{
 			if (_carouselViewLayoutListener is not null)

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

@@ -25,6 +25,7 @@ public partial class CarouselViewHandler : ItemsViewHandler<CarouselView>
 		WScrollBarVisibility? _verticalScrollBarVisibilityWithoutLoop;
 		Size _currentSize;
 		bool _isCarouselViewReady;
+		bool _isInternalPositionUpdate;
 		NotifyCollectionChangedEventHandler _collectionChanged;
 		readonly WeakNotifyCollectionChangedProxy _proxy = new();
 
@@ -387,7 +388,9 @@ void UpdateCurrentItem()
 			if (currentItemPosition < 0 || currentItemPosition >= ItemCount)
 				return;
 
-			ItemsView.ScrollTo(currentItemPosition, position: ScrollToPosition.Center, animate: ItemsView.AnimateCurrentItemChanges);
+			// Disable animation during collection changes to prevent cascading scroll events
+			var animate = ItemsView.AnimateCurrentItemChanges && !_isInternalPositionUpdate;
+			ItemsView.ScrollTo(currentItemPosition, position: ScrollToPosition.Center, animate: animate);
 		}
 
 		void UpdatePosition()
@@ -523,6 +526,9 @@ void OnScrollViewChanged(object sender, ScrollViewerViewChangedEventArgs e)
 
 		void OnCollectionItemsSourceChanged(object sender, NotifyCollectionChangedEventArgs e)
 		{
+			// Set flag to disable animation during collection changes
+			_isInternalPositionUpdate = true;
+
 			var carouselPosition = ItemsView.Position;
 			var currentItemPosition = GetItemPositionInCarousel(ItemsView.CurrentItem);
 			var count = (sender as IList).Count;
@@ -547,10 +553,23 @@ void OnCollectionItemsSourceChanged(object sender, NotifyCollectionChangedEventA
 				&& currentItemPosition != -1)
 			{
 				carouselPosition = currentItemPosition;
+				ItemsView.Position = currentItemPosition;
+			}
+
+			if (ItemsView.ItemsUpdatingScrollMode == ItemsUpdatingScrollMode.KeepLastItemInView)
+			{
+				carouselPosition = count == 0 ? 0 : count - 1;
+			}
+			else if (ItemsView.ItemsUpdatingScrollMode == ItemsUpdatingScrollMode.KeepItemsInView)
+			{
+				carouselPosition = 0;
 			}
 
 			SetCarouselViewCurrentItem(carouselPosition);
 			SetCarouselViewPosition(carouselPosition);
+
+			// Reset flag after collection operations complete
+			_isInternalPositionUpdate = false;
 		}
 
 		void OnListViewSizeChanged(object sender, SizeChangedEventArgs e) => Resize(e.NewSize);

src/Controls/tests/TestCases.HostApp/Issues/Issue29529.cs

@@ -0,0 +1,113 @@
+using System.Collections.ObjectModel;
+
+namespace Maui.Controls.Sample.Issues;
+
+[Issue(IssueTracker.Github, 29529, "CurrentItemChangedEventArgs and PositionChangedEventArgs Not Updating Correctly in CarouselView", PlatformAffected.UWP | PlatformAffected.Android)]
+public class Issue29529 : ContentPage
+{
+	int _positionChangedCount = 0;
+	int _currentItemChangedCount = 0;
+
+	public Issue29529()
+	{
+		var verticalStackLayout = new VerticalStackLayout();
+		var carouselItems = new ObservableCollection<string>
+		{
+			"Item 1",
+			"Item 2",
+			"Item 3",
+			"Item 4",
+			"Item 5",
+			"Item 6",
+		};
+
+		CarouselView carouselView = new CarouselView
+		{
+			ItemsSource = carouselItems,
+			AutomationId = "carouselview",
+			Position = 3,
+			ItemsUpdatingScrollMode = ItemsUpdatingScrollMode.KeepItemsInView,
+			Loop = false,
+			HeightRequest = 300,
+			ItemTemplate = new DataTemplate(() =>
+			{
+				var grid = new Grid
+				{
+					Padding = 10
+				};
+
+				var label = new Label
+				{
+					VerticalOptions = LayoutOptions.Center,
+					HorizontalOptions = LayoutOptions.Center,
+					FontSize = 18,
+				};
+				label.SetBinding(Label.TextProperty, ".");
+				label.SetBinding(Label.AutomationIdProperty, ".");
+
+				grid.Children.Add(label);
+				return grid;
+			}),
+			HorizontalOptions = LayoutOptions.Fill,
+		};
+
+		var positionLabel = new Label
+		{
+			AutomationId = "positionLabel",
+			Text = $"Current Position{carouselView.Position}",
+			HorizontalOptions = LayoutOptions.Center,
+			Padding = new Thickness(20),
+		};
+
+		var itemLabel = new Label
+		{
+			AutomationId = "itemLabel",
+			Text = $"Current Item{carouselView.CurrentItem}",
+			HorizontalOptions = LayoutOptions.Center,
+			Padding = new Thickness(20),
+		};
+
+		var eventCountLabel = new Label
+		{
+			AutomationId = "eventCountLabel",
+			Text = "PositionChanged: 0, CurrentItemChanged: 0",
+			HorizontalOptions = LayoutOptions.Center,
+			Padding = new Thickness(20),
+		};
+
+		carouselView.PositionChanged += (s, e) =>
+		{
+			_positionChangedCount++;
+			positionLabel.Text = $"Current Position: {e.CurrentPosition}, Previous Position: {e.PreviousPosition}";
+			eventCountLabel.Text = $"PositionChanged: {_positionChangedCount}, CurrentItemChanged: {_currentItemChangedCount}";
+		};
+
+		carouselView.CurrentItemChanged += (s, e) =>
+		{
+			_currentItemChangedCount++;
+			itemLabel.Text = $"Current Item: {e.CurrentItem}, Previous Item: {e.PreviousItem}";
+			eventCountLabel.Text = $"PositionChanged: {_positionChangedCount}, CurrentItemChanged: {_currentItemChangedCount}";
+		};
+
+		var insertButton = new Button
+		{
+			Text = "Insert item at index 0",
+			AutomationId = "InsertButton",
+			Margin = new Thickness(20),
+		};
+
+		insertButton.Clicked += (sender, e) =>
+		{
+			_positionChangedCount = 0;
+			_currentItemChangedCount = 0;
+			carouselItems.Insert(6, "Item 0");
+		};
+
+		verticalStackLayout.Children.Add(carouselView);
+		verticalStackLayout.Children.Add(insertButton);
+		verticalStackLayout.Children.Add(positionLabel);
+		verticalStackLayout.Children.Add(itemLabel);
+		verticalStackLayout.Children.Add(eventCountLabel);
+		Content = verticalStackLayout;
+	}
+}

src/Controls/tests/TestCases.Shared.Tests/Tests/Issues/Issue29529.cs

@@ -0,0 +1,28 @@
+using NUnit.Framework;
+using UITest.Appium;
+using UITest.Core;
+
+namespace Microsoft.Maui.TestCases.Tests.Issues;
+
+public class Issue29529 : _IssuesUITest
+{
+	public override string Issue => "CurrentItemChangedEventArgs and PositionChangedEventArgs Not Updating Correctly in CarouselView";
+
+	public Issue29529(TestDevice device)
+	: base(device)
+	{ }
+
+	[Test]
+	[Category(UITestCategories.CarouselView)]
+	public void Issue29529VerifyPreviousPositionOnInsert()
+	{
+		App.WaitForElement("carouselview");
+		App.Tap("InsertButton");
+		var text = App.FindElement("positionLabel").GetText();
+		Assert.That(text, Is.EqualTo("Current Position: 0, Previous Position: 3"));
+		text = App.FindElement("itemLabel").GetText();
+		Assert.That(text, Is.EqualTo("Current Item: Item 1, Previous Item: Item 4"));
+		text = App.FindElement("eventCountLabel").GetText();
+		Assert.That(text, Is.EqualTo("PositionChanged: 1, CurrentItemChanged: 1"));
+	}
+}