Fix CarouselView Regression #28955

kubaflo · 2025-04-12T18:03:43Z

Description

A proposed fix for a minor regression introduced in this pr #28225

Issues Fixed

Before	After

@albyrock87

Copilot

Copilot reviewed 4 out of 5 changed files in this pull request and generated 1 comment.

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src/Controls/tests/TestCases.HostApp/Issues/Issue28930.xaml: Language not supported

Copilot · 2025-04-12T18:03:56Z

src/Controls/src/Core/Handlers/Items/iOS/TemplatedCell.cs

@@ -104,6 +106,13 @@ public override UICollectionViewLayoutAttributes PreferredLayoutAttributesFittin
 				var size = ConstrainedSize == default ? Measure() : ConstrainedSize;
 				_size = size.ToSize();
 				_needsArrange = true;
+
+				if (IsCarouselViewCell && PlatformHandler?.VirtualView is { } virtualView)


Consider adding an inline comment explaining the rationale for applying a custom measurement override for carousel view cells to aid future maintainers.

azure-pipelines · 2025-04-12T23:23:25Z

Azure Pipelines successfully started running 3 pipeline(s).

Bamich · 2025-04-13T03:11:09Z

Hi! I tried this, it seems ItemsLayout="HorizontalList" is not respected. All CarouselViews in my project become vertical (at least child Grid elements are arranged vertically)

albyrock87 · 2025-04-13T08:27:58Z

@Bamich have you tried this after this merge cfe6e69 ?
If so, may you show a sample code, including whether you're using CV1 or CV2 handler?
Because all UITests pass here, including the one which fixes the issue.
Thanks

Bamich · 2025-04-13T18:44:16Z

@albyrock87 @kubaflo I tested it again. CV1 seems to work as expected. But CV2 doesn't - all child elements are arranged vertically.

This is also easily reproduced in the original sample:

Turn on CV2
Run sample
Most importantly - try to scroll the carousel horizontally, and then vertically, you will see that the scroll will go exactly vertically. In statics it is not obvious, you need to start scrolling :)

Direct ItemsLayout="HorizontalList" does not affect the behavior.

scr_rec.mov

You can also replace the MainPage.xml code in the original example with this simpler one, and then scroll the CarouselView in different directions:

<?xml version="1.0" encoding="utf-8" ?>
<ContentPage
	x:Class="IssueLabeliOS9060.MainPage"
	xmlns="http://schemas.microsoft.com/dotnet/2021/maui" xmlns:x="http://schemas.microsoft.com/winfx/2009/xaml"
	xmlns:local="clr-namespace:IssueLabeliOS9060">
	<Grid>
		<Border Padding="10">
			<Grid VerticalOptions="Fill">
				<CarouselView HeightRequest="200" x:Name="MyCarousel" EmptyView="No data">
					<CarouselView.ItemsSource>
						<x:Array Type="{x:Type x:String}">
							<x:String>First</x:String>
							<x:String>Second</x:String>
							<x:String>Third</x:String>
						</x:Array>
					</CarouselView.ItemsSource>
					<CarouselView.ItemTemplate>
						<DataTemplate>
							<Grid
								Padding="20"
								HorizontalOptions="Fill" VerticalOptions="Fill">
								<Label
									Text="{Binding .}"
									HorizontalOptions="Fill" VerticalOptions="Fill"
									BackgroundColor="red" />
							</Grid>
						</DataTemplate>
					</CarouselView.ItemTemplate>
				</CarouselView>
			</Grid>
		</Border>
	</Grid>

</ContentPage>

jsuarezruiz

There are some CarouselView UITests failing on iOS/Catalyst:

The app was expected to be running still, investigate as possible crash

Could you review if are related with the changes?

albyrock87 · 2025-04-14T10:01:44Z

@jsuarezruiz the fix is ready here kubaflo#4

I really don't understand why, but passing the scroll direction makes the Carousel2 handler crash the app without any message :/
Anyway we don't need that information in the new CarouselTemplatedCell2 🙂
I added a comment in the code and an additional test in Issue28930 to verify the carousel can scroll horizontally.

We can wait for the merge or you can cherry pick and run AZP immediately

Bamich · 2025-04-14T16:22:36Z

I have a proposal. It doesn't seem to be directly related to this PR, but since it's called "Improve iOS CarouselView performance", maybe we should fix this right away? If I set the scroll index for a CarouselView with CV2 on iOS "too early" I get a random exception "cannot access disposed object NSPathIndex". Perhaps we should move the projectedPosition calculation a little lower in CarouselViewController2.cs by changing this part:

<...>

// with Task.Delay(100) below it results in "cannot access disposed object NSPathIndex"
var projectedPosition = NSIndexPath.FromItemSection(position, _section);

if (LoopItemsSource.Loop)
{
	//We need to set the position to the correct position since we added 1 item at the beginning
	projectedPosition = GetScrollToIndexPath(position);
}

var uICollectionViewScrollPosition = IsHorizontal ? UICollectionViewScrollPosition.CenteredHorizontally :
	UICollectionViewScrollPosition.CenteredVertically;

await Task.Delay(100).ContinueWith((t) =>
{
	MainThread.BeginInvokeOnMainThread(() =>
	{
		if (!IsViewLoaded)
		{
			return;
		}
		InitialPositionSet = true;

		if (ItemsSource is null || ItemsSource.ItemCount == 0)
		{
			return;
		}

		CollectionView.ScrollToItem(projectedPosition, uICollectionViewScrollPosition, false);

		//Set the position on VirtualView to update the CurrentItem also
		SetPosition(position);

		UpdateVisualStates();
	});

});

<...>

to something like this?

<...>

var uICollectionViewScrollPosition = IsHorizontal ? UICollectionViewScrollPosition.CenteredHorizontally : 
	UICollectionViewScrollPosition.CenteredVertically;

// just wait..
await Task.Delay(100);

MainThread.BeginInvokeOnMainThread(() =>
{
	if (!IsViewLoaded)
	{
		return;
	}

	InitialPositionSet = true;

	if (ItemsSource is null || ItemsSource.ItemCount == 0)
	{
		return;
	}

	// Get projectedPosition immediately before use (no crash)
	NSIndexPath projectedPosition = LoopItemsSource.Loop
		? GetScrollToIndexPath(position)
		: NSIndexPath.FromItemSection(position, _section);

	CollectionView.ScrollToItem(projectedPosition, uICollectionViewScrollPosition, false);

		//Set the position on VirtualView to update the CurrentItem also
		SetPosition(position);

		UpdateVisualStates();
});

<...>

Thanks

albyrock87 · 2025-04-14T16:45:04Z

@Bamich I think that's reasonable.
In the mean time, may you verify if the last commit here fixes the issue?
I believe so given I also added a check in the UITest, but if you can confirm I'd appreciate.
Thanks

PureWeen · 2025-04-14T18:21:20Z

/azp run

azure-pipelines · 2025-04-14T18:21:41Z

Azure Pipelines successfully started running 3 pipeline(s).

Bamich · 2025-04-14T18:48:37Z

@albyrock87 Yes, I checked and confirm that the last commit fixes the scroll orientation issue

jsuarezruiz · 2025-04-15T06:50:16Z

/azp run

azure-pipelines · 2025-04-15T06:50:40Z

Azure Pipelines successfully started running 3 pipeline(s).

MartyIX · 2025-04-15T11:07:07Z

src/TestUtils/src/UITest.Appium/HelperExtensions.cs

@@ -799,7 +814,8 @@ public static bool WaitForTextToBePresentInElement(this IApp app, string automat
 			while (true)
 			{
 				var element = app.FindElements(automationId).FirstOrDefault();
-				if (element != null && (element.GetText()?.Contains(text, StringComparison.OrdinalIgnoreCase) ?? false))
+
+				if (element != null && element.TryGetText(out var s) && s.Contains(text, StringComparison.OrdinalIgnoreCase))


If you need to touch the PR again, this can be:

Suggested change

if (element != null && element.TryGetText(out var s) && s.Contains(text, StringComparison.OrdinalIgnoreCase))

if (element is not null && element.TryGetText(out var s) && s.Contains(text, StringComparison.OrdinalIgnoreCase))

rmarinho · 2025-04-15T11:57:32Z

/azp run

azure-pipelines · 2025-04-15T11:57:53Z

Azure Pipelines successfully started running 3 pipeline(s).

rmarinho · 2025-04-15T13:27:51Z

src/Controls/src/Core/Handlers/Items2/iOS/ItemsViewController2.cs

@@ -61,6 +61,7 @@ public void UpdateLayout(UICollectionViewLayout newLayout)

 			if (newLayout is UICollectionViewCompositionalLayout compositionalLayout)
 			{
+				// Note: on carousel layout, the scroll direction is always vertical


I don t understand this comment, can t we have a CarouselView for scroll left and right or up and down? So 2 directions?

What I'm saying is that this variable on carousel is always set to vertical, even when having a horizontal carousel.
Horizontal carousel is made in a different way.

I think we do it in this way (always set to vertical) to achieve horizontal paging with snapping (GroupPagingCentered). Thanks to it, we can use OrthogonalScrollingBehavior.GroupPagingCentered to scroll the section horizontally. And even if CarouselView is vertically oriented, each section scrolls horizontally — which results in the carousel-style behavior

rmarinho · 2025-04-16T10:45:11Z

src/Controls/src/Core/Handlers/Items/iOS/ItemsViewController.cs

@@ -521,6 +521,11 @@ protected virtual string DetermineCellReuseId(NSIndexPath indexPath)
 				: VerticalDefaultCell.ReuseId;
 		}

+		private protected virtual (Type CellType, string CellTypeReuseId) DetermineTemplatedCellType()
+		{
+			return (ItemsViewLayout.ScrollDirection == UICollectionViewScrollDirection.Vertical ? typeof(VerticalCell) : typeof(HorizontalCell), "maui");


Shouldn't this use the ReuseID ?

It wasn't using it, so I kept the old reuseId creation logic.

Oh this was just reverted to what it was?

I'm referring to line 508 above

var reuseId = $"_maui_{cellOrientation}_{dataTemplate.Id}";

It was using this maui string so I simply kept it like that.
While CV2 is a different story: there it was using the reuseId so I used it.

The base branch was changed.

rmarinho · 2025-04-16T11:30:51Z

/rebase

…50407.3 (dotnet#28892) Microsoft.DotNet.XHarness.CLI , Microsoft.DotNet.XHarness.TestRunners.Common , Microsoft.DotNet.XHarness.TestRunners.Xunit From Version 9.0.0-prerelease.25203.2 -> To Version 9.0.0-prerelease.25207.3 Co-authored-by: dotnet-maestro[bot] <dotnet-maestro[bot]@users.noreply.github.com>

* [ai]Add release notes prompt * Improve prompt release notes * [ai] improve prompt * [ai] Try map commits to github users * Small update to get correct github user * [ai] Add list of common users * [ai] Remove extra vriable

rmarinho · 2025-04-16T16:18:54Z

/rebase

kubaflo · 2025-04-16T18:24:17Z

Closed in favour of #29035

Update Versions.props to 9.0.60 SR6 (dotnet#28899)

d870988

Copilot AI review requested due to automatic review settings April 12, 2025 18:03

kubaflo requested a review from a team as a code owner April 12, 2025 18:03

kubaflo requested review from jfversluis and mattleibow April 12, 2025 18:03

Copilot AI reviewed Apr 12, 2025

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dotnet-policy-service bot added the community ✨ Community Contribution label Apr 12, 2025

kubaflo self-assigned this Apr 12, 2025

kubaflo added platform/ios area-controls-collectionview CollectionView, CarouselView, IndicatorView labels Apr 12, 2025

kubaflo assigned albyrock87 Apr 13, 2025

kubaflo changed the title ~~Incorrect label LineBreakMode in IOS inside CarouselView - fix~~ Improve iOS CarouselView performance Apr 13, 2025

jsuarezruiz requested changes Apr 14, 2025

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kubaflo mentioned this pull request Apr 14, 2025

CarouselView Item Changes Unexpectedly on Orientation Change in CV2 #28972

Open

albyrock87 mentioned this pull request Apr 14, 2025

Fix carousel initial position bug kubaflo/maui#5

Merged

PureWeen changed the title ~~Improve iOS CarouselView performance~~ Fix CarouselView Regression Apr 14, 2025

PureWeen added this to the .NET 9 SR6.1 milestone Apr 14, 2025

MartyIX reviewed Apr 15, 2025

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rmarinho previously approved these changes Apr 16, 2025

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rmarinho added this to MAUI SDK Ongoing Apr 16, 2025

github-project-automation bot moved this to Todo in MAUI SDK Ongoing Apr 16, 2025

rmarinho moved this from Todo to Approved in MAUI SDK Ongoing Apr 16, 2025

rmarinho changed the base branch from main to release/9.0.1xx-sr6 April 16, 2025 11:29

PureWeen and others added 10 commits April 16, 2025 11:31

Update Versions.props to 9.0.70 SR7 (dotnet#28900)

a97089d

Update bug-report.yml with latest public releases (dotnet#28922)

6621640

fix (dotnet#28919)

3d3b00e

[ai] Add release notes prompt (dotnet#28896)

0cec954

* [ai]Add release notes prompt * Improve prompt release notes * [ai] improve prompt * [ai] Try map commits to github users * Small update to get correct github user * [ai] Add list of common users * [ai] Remove extra vriable

Incorrect label LineBreakMode in IOS inside CarouselView - fix

8d95ee7

Fix carousel cell measurement

84ffd5e

Fix regression due to passing scroll direction into the layout

fcc9025

Fix carousel initial position bug

4011f42

Fix UI tests

4f0d868

github-actions bot force-pushed the fix-28930 branch from 5e7524c to 4f0d868 Compare April 16, 2025 11:31

rmarinho changed the base branch from release/9.0.1xx-sr6 to main April 16, 2025 16:18

albyrock87 mentioned this pull request Apr 16, 2025

Fix CarouselView layout SR6 regressions #29035

Merged

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github-project-automation bot moved this from Approved to Done in MAUI SDK Ongoing Apr 16, 2025

github-actions bot locked and limited conversation to collaborators May 17, 2025

	if (element != null && element.TryGetText(out var s) && s.Contains(text, StringComparison.OrdinalIgnoreCase))
	if (element is not null && element.TryGetText(out var s) && s.Contains(text, StringComparison.OrdinalIgnoreCase))

Fix CarouselView Regression #28955

Fix CarouselView Regression #28955

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