Fixed [Windows] KeepLastItemInView Behavior Not Working as Expected in CarouselView

[NanthiniMahalingam]

Note

Are you waiting for the changes in this PR to be merged?
It would be very helpful if you could test the resulting artifacts from this PR and let us know in a comment if this change resolves your issue. Thank you!

Root Cause

• The CarouselView does not correctly identify the last item when KeepLastInView is enabled due to the presence of fake (looping) items.
• In the OnItemsVectorChanged method, the item count returned includes these fake items, which prevents the actual last item from being recognized.
• When dynamically resizing the window, the ItemsView position changes based on the CenterVisibleIndex value within the CarouselScrolled method. As a result, the current item scrolls away from the last item unexpectedly.

Description of Change

• Updated the OnItemsVectorChanged method to use the CollectionViewSource.View of ItemCount to retrieve the actual items of the CarouselView, avoiding fake items.
• This ensures that the correct last item is identified and displayed when KeepLastInView is set.
• Restricted the ItemsView.ScrollTo call in UpdateCurrentItem method when ItemsView.Position is equal to the current item’s position due to items view position changed based on CenterVisibleIndex value inside the CarosuelScrolled method which caused that the current items has been scrolled from the last item while dynamically resizing the window.

Validated the behaviour in the following platforms

• Android
• Windows ,
• iOS, MacOS -CarouselView Fails to Keep Last Item in View on iOS and macOS KeepLastItemInView not working on iOS #18029

Issues Fixed

Fixes #29420

Output

Windows

Before	After
Issue29420_Before.mp4	Issue29420_After.mp4

[dotnet-policy-service]

Hey there @@NanthiniMahalingam! Thank you so much for your PR! Someone from the team will get assigned to your PR shortly and we'll get it reviewed.

[jsuarezruiz]

/azp run MAUI-UITests-public

[azure-pipelines]

Azure Pipelines successfully started running 1 pipeline(s).

[Copilot]

Pull Request Overview

This PR fixes the KeepLastItemInView behavior in CarouselView on Windows by adjusting how the last item is identified and preventing unwanted scroll operations when the carousel is resized.

• Updated the item count calculation in OnItemsVectorChanged to avoid using fake looping items.
• Restricted the ScrollTo call in UpdateCurrentItem when the current item is already in view.
• Added test cases in both shared tests and the host app to validate the behavior on Windows (and other platforms).

Reviewed Changes

Copilot reviewed 4 out of 4 changed files in this pull request and generated 2 comments.

File	Description
src/Controls/tests/TestCases.Shared.Tests/Tests/Issues/Issue29420.cs	Added test case for KeepLastItemInView on platforms failing the behavior
src/Controls/tests/TestCases.HostApp/Issues/Issue29420.cs	Host test implementation verifying the fixed behavior
src/Controls/src/Core/Handlers/Items/ItemsViewHandler.Windows.cs	Modified item count logic to differentiate between fake looping items and actual items
src/Controls/src/Core/Handlers/Items/CarouselViewHandler.Windows.cs	Added a safeguard in UpdateCurrentItem to avoid unnecessary scroll operations

[Copilot]

[nitpick] Consider adding an inline comment clarifying why VirtualView is being checked against CollectionView and what types are expected; this will help future maintainers understand the intended behavior when selecting between items.Count and ItemCount.

Suggested change

	// When looping is enabled in CarouselView, Items.Count returns the FakeCount instead of the actual item count.
	// When looping is enabled in CarouselView, Items.Count returns the FakeCount instead of the actual item count.
	// Use items.Count for CollectionView to account for this behavior; otherwise, use ItemCount for other types.

[Copilot]

[nitpick] It would be helpful to add a brief comment explaining the rationale for including the check against ItemsView.Position, so that the intention to prevent unnecessary scrolling when the current item is already visible is clearly documented.

Suggested change

	// If the current item is already visible (ItemsView.Position == currentItemPosition),
	// avoid unnecessary scrolling to improve performance and user experience.