[Windows] Fixed KeepLastItemInView Behavior Not Working as Expected in CarouselView by NanthiniMahalingam · Pull Request #29550 · dotnet/maui

NanthiniMahalingam · 2025-05-16T14:09:06Z

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
Fixes #29448

Output

Windows

Before	After
Issue29420_Before.mp4	Issue29420_After.mp4

jsuarezruiz · 2025-05-19T06:20:30Z

/azp run MAUI-UITests-public

azure-pipelines · 2025-05-19T06:20:42Z

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 · 2025-05-19T15:25:32Z

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

 				return;

-			var itemsCount = items.Count;
+			// When looping is enabled in CarouselView, Items.Count returns the FakeCount instead of the actual item count.


[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 · 2025-05-19T15:25:32Z

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

@@ -381,8 +381,10 @@ void UpdateCurrentItem()

 			var currentItemPosition = GetItemPositionInCarousel(ItemsView.CurrentItem);



[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.

jsuarezruiz · 2025-05-22T06:25:46Z

/azp run MAUI-UITests-public

azure-pipelines · 2025-05-22T06:25:56Z

Azure Pipelines successfully started running 1 pipeline(s).

jsuarezruiz · 2025-05-30T10:21:32Z

/azp run MAUI-UITests-public

azure-pipelines · 2025-05-30T10:21:43Z

Azure Pipelines successfully started running 1 pipeline(s).

src/Controls/tests/TestCases.Shared.Tests/Tests/Issues/Issue29420.cs

jsuarezruiz · 2025-06-03T09:14:18Z

/azp run MAUI-UITests-public

azure-pipelines · 2025-06-03T09:14:30Z

Azure Pipelines successfully started running 1 pipeline(s).

jsuarezruiz · 2025-06-04T06:57:45Z

/azp run MAUI-UITests-public

azure-pipelines · 2025-06-04T06:57:56Z

Azure Pipelines successfully started running 1 pipeline(s).

jsuarezruiz · 2025-06-17T07:57:43Z

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

 			var currentItemPosition = GetItemPositionInCarousel(ItemsView.CurrentItem);

-			if (currentItemPosition < 0 || currentItemPosition >= ItemCount)
+			if (currentItemPosition < 0 || currentItemPosition >= ItemCount || ItemsView.Position == currentItemPosition)


Not an extra long condition, but can increase the readability here adding a couple of variables:

bool isOutOfBounds = currentItemPosition < 0 || currentItemPosition >= ItemCount; bool isSamePosition = ItemsView.Position == currentItemPosition; if (isOutOfBounds || isSamePosition) return;

Not an extra long condition, but can increase the readability here adding a couple of variables:

bool isOutOfBounds = currentItemPosition < 0 || currentItemPosition >= ItemCount; bool isSamePosition = ItemsView.Position == currentItemPosition; if (isOutOfBounds || isSamePosition) return;

Hi @jsuarezruiz ,
I've refined the fix according to your suggestion to enhance readability.

jsuarezruiz · 2025-06-30T07:07:02Z

/azp run MAUI-UITests-public

azure-pipelines · 2025-06-30T07:07:16Z

Azure Pipelines successfully started running 1 pipeline(s).

github-actions · 2025-12-09T07:46:57Z

🚀 Dogfood this PR with:

⚠️ WARNING: Do not do this without first carefully reviewing the code of this PR to satisfy yourself it is safe.

curl -fsSL https://raw.githubusercontent.com/dotnet/maui/main/eng/scripts/get-maui-pr.sh | bash -s -- 29550

Or

Run remotely in PowerShell:

iex "& { $(irm https://raw.githubusercontent.com/dotnet/maui/main/eng/scripts/get-maui-pr.ps1) } 29550"

kubaflo · 2026-03-26T20:08:50Z

/azp run maui-pr-uitests , maui-pr-devicetests

kubaflo

Could you please resolve conflicts?

SubhikshaSf4851 · 2026-03-27T10:41:55Z

@kubaflo I have resolved the conflicts

MauiBot · 2026-03-27T13:11:30Z

🚦 Gate - Test Before and After Fix

📊 Expand Full Gate — f4edce5 · Added missed logic on resolving conflict

Gate Result: ❌ FAILED

Platform: windows

dotnet-policy-service bot added community ✨ Community Contribution partner/syncfusion Issues / PR's with Syncfusion collaboration labels May 16, 2025

jsuarezruiz added platform/windows area-controls-collectionview CollectionView, CarouselView, IndicatorView labels May 19, 2025

NanthiniMahalingam marked this pull request as ready for review May 19, 2025 15:24

Copilot AI review requested due to automatic review settings May 19, 2025 15:24

NanthiniMahalingam requested a review from a team as a code owner May 19, 2025 15:24

NanthiniMahalingam requested review from jfversluis and jsuarezruiz May 19, 2025 15:24

Copilot AI reviewed May 19, 2025

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jsuarezruiz suggested changes Jun 2, 2025

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src/Controls/tests/TestCases.Shared.Tests/Tests/Issues/Issue29420.cs Outdated Show resolved Hide resolved

jsuarezruiz previously approved these changes Jun 17, 2025

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NanthiniMahalingam dismissed jsuarezruiz’s stale review via 98b5f14 June 18, 2025 06:30

NanthiniMahalingam changed the title ~~Fixed [Windows] KeepLastItemInView Behavior Not Working as Expected in CarouselView~~ [Windows] Fixed KeepLastItemInView Behavior Not Working as Expected in CarouselView Jun 19, 2025

NanthiniMahalingam force-pushed the fix-29420 branch from 98b5f14 to 71f412c Compare December 9, 2025 07:46

NanthiniMahalingam force-pushed the fix-29420 branch from 71f412c to 991f3a2 Compare December 24, 2025 06:27

build-analysis bot mentioned this pull request Dec 24, 2025

slow macOS - "##[error]The job running on agent Azure Pipelines 9 ran longer than the maximum time of 60 minutes." dotnet/dnceng#1883

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3 tasks

build-analysis bot mentioned this pull request Mar 24, 2026

[MacCatalyst] WebViewShouldLoadEncodedUrl flaky on macOS 26 Helix queue (TimeoutException) #34577

Open

kubaflo approved these changes Mar 26, 2026

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kubaflo changed the base branch from main to inflight/current March 26, 2026 20:11

kubaflo requested changes Mar 26, 2026

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NanthiniMahalingam and others added 13 commits March 27, 2026 12:53

Added the fix

08b73e0

Updated the fix

19753b7

Added the test case

6fe32f5

Updated the test case.

7deddb1

Updated the fix

03a9fd7

Updated the fix and test case.

01c3fbb

Updated the test case and added snapshot

274b78b

Updated the test case.

0024132

Added the output images.

7d807ed

Updated the fix.

1ed2936

Updated the test case

8dfb9a5

Addressed review Summary

7c2ceb8

revert the Suggestion

2380dad

SubhikshaSf4851 force-pushed the fix-29420 branch from 1b23515 to 2380dad Compare March 27, 2026 07:39

Added missed logic on resolving conflict

f4edce5

	// 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.

		@@ -381,8 +381,10 @@ void UpdateCurrentItem()

		var currentItemPosition = GetItemPositionInCarousel(ItemsView.CurrentItem);



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

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