[Android] Fix RemainingItemsThresholdReachedCommand not firing when CollectionView has Header and Footer both defined

[SuthiYuvaraj]

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!

Issue Description

In Android, the RemainingThresholdReached command is not triggered when both a Header and a Footer are defined for the collection.

RootCause

The SendRemainingThresholdReached method is triggered based on the LastVisibleIndex and the ItemCount provided by the ItemAdapter. However, on Android, when both a Header and a Footer are defined, the ItemCount consider it, leading to incorrect triggering logic.

Description of Change

Updated the logic to ensure that the ItemCount correctly includes both the Header and Footer. This change ensures that the Footer becomes visible as expected and that the SendRemainingThresholdReached command is properly executed.

Issues Fixed

Fixes #29588

Tested the behaviour in the following platforms

• Android
• Windows
• iOS
• Mac

Output Screenshot

Before Issue Fix	After Issue Fix
RemainingThresholdBefore.mov	RemainingThresholdAfter.mov

[jsuarezruiz]

/azp run MAUI-UITests-public

[azure-pipelines]

Azure Pipelines successfully started running 1 pipeline(s).

[jsuarezruiz]

With the changes, firstDataItemIndex is set to 1 only when both Header and Footer exist. However, if only Header is present, the value should be 1 too, right?

[SuthiYuvaraj]

Yes @jsuarezruiz , firstDataItemIndex should be set to 1 whenever only the header is present. Since the header and footer affect indexing independently, they should be evaluated separately.

I've updated the logic to reflect this and optimized the code for improved clarity and efficiency. Please review the modified fix and let me know if any further changes are required.

[jsuarezruiz]

Here, could simplify the logic by consolidating checks:

bool isThresholdReached = (Last == lastDataItemIndex - 1) || (lastDataItemIndex - 1 - Last <= _itemsView.RemainingItemsThreshold);

if (isThresholdReached)
{
    _itemsView.SendRemainingItemsThresholdReached();
}

[SuthiYuvaraj]

@jsuarezruiz , I've optimized the logic for improved clarity and efficiency. Please review the modified fix and let me know if any further changes are required.

[MartyIX]

super nit: File-scope namespace can be used here.

[SuthiYuvaraj]

@MartyIX , Thanks for the feedback , I have updated the code changes, let me know if any further changes are required.

[jsuarezruiz]

/azp run MAUI-UITests-public

[azure-pipelines]

Azure Pipelines successfully started running 1 pipeline(s).

[Copilot]

Pull request overview

This PR fixes a bug where the RemainingItemsThresholdReachedCommand fails to fire in Android CollectionView when both a Header and Footer are defined. The root cause is that the threshold calculation didn't properly account for both header and footer items being included in the adapter's ItemCount, leading to incorrect triggering logic.

Key Changes:

• Updated threshold calculation logic in RecyclerViewScrollListener.cs to correctly subtract header and footer counts from ItemCount
• Consolidated multiple switch/case branches into a single boolean expression for cleaner code
• Added comprehensive UI test to verify the fix works with header and footer present

Reviewed changes

Copilot reviewed 3 out of 3 changed files in this pull request and generated 4 comments.

File	Description
src/Controls/src/Core/Handlers/Items/Android/RecyclerViewScrollListener.cs	Refactored threshold reached logic to properly calculate item count excluding headers/footers, and simplified control flow from switch statement to boolean expression
src/Controls/tests/TestCases.Shared.Tests/Tests/Issues/Issue29588.cs	Added NUnit UI test that scrolls CollectionView and verifies threshold command triggers
src/Controls/tests/TestCases.HostApp/Issues/Issue29588.cs	Added test page with 20 initial items, header, footer, and async command that updates label when threshold reached

[Copilot]

The boundary check Last > modifiedItemCount should be Last >= modifiedItemCount. If there are 20 items (indices 0-19), modifiedItemCount would be 20, and a Last value of 20 would be invalid but would not be caught by this check. Valid item indices range from 0 to modifiedItemCount - 1, so any index >= modifiedItemCount should return early.

Suggested change

	if (Last < headerValue || Last > modifiedItemCount)
	if (Last < headerValue || Last >= modifiedItemCount)

[Copilot]

Typo in the Issue description: "RemainingItemsThresholdReachedcommand" should have a space before "command".

Suggested change

	public override string Issue => "CollectionView RemainingItemsThresholdReachedcommand should trigger on scroll near end";
	public override string Issue => "CollectionView RemainingItemsThresholdReached command should trigger on scroll near end";

[Copilot]

Typo in the Issue description: "RemainingItemsThresholdReachedcommand" should have a space before "command".

Suggested change

	[Issue(IssueTracker.Github, 29588, "CollectionView RemainingItemsThresholdReachedcommand should trigger on scroll near end", PlatformAffected.Android)]
	[Issue(IssueTracker.Github, 29588, "CollectionView RemainingItemsThresholdReached command should trigger on scroll near end", PlatformAffected.Android)]

[Copilot]

Potential race condition: The RemainingItemReachedCommand is async and includes a 1.5 second delay (Task.Delay(1500) in LoadMoreItemsAsync()), but the test immediately checks the label text after scrolling. The assertion on line 25 might execute before ThresholdStatus is updated to "Threshold reached". Consider adding a wait/polling mechanism after the scrolling to ensure the async command completes, or use a framework method that waits for the text to change to the expected value.

Suggested change

	Assert.That(App.FindElement("29588ThresholdLabel").GetText(), Is.EqualTo("Threshold reached"));
	// Wait up to 5 seconds for the label text to become "Threshold reached"
	const int timeoutMs = 5000;
	const int pollIntervalMs = 200;
	var start = DateTime.UtcNow;
	string labelText = "";
	do
	{
	labelText = App.FindElement("29588ThresholdLabel").GetText();
	if (labelText == "Threshold reached")
	break;
	System.Threading.Thread.Sleep(pollIntervalMs);
	}
	while ((DateTime.UtcNow - start).TotalMilliseconds < timeoutMs);
	Assert.That(labelText, Is.EqualTo("Threshold reached"));

[kubaflo]

Hi @SuthiYuvaraj looks good! Can you have a look at the AI Summary and check if it makes sense to you :)

[sheiksyedm]

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

[azure-pipelines]

Azure Pipelines successfully started running 2 pipeline(s).