Can nest this two conditions in a single one, but would be better to create a variable to increase the readability:

 var shouldUpdatePosition = 
     currentItemPosition != carouselPosition &&
     ItemsView.ItemsUpdatingScrollMode == ItemsUpdatingScrollMode.KeepItemsInView &&
     InitialPositionSet && 
     currentItemPosition > -1;

@jsuarezruiz, I have updated the code section based on your suggestions.

Should this move into the GetPositionWhenAddingItems method for consistency?

We have setters in the GetPositionWhenResetItems method:

int GetPositionWhenResetItems()
{
	//If we are reseting the collection Position should go to 0
	ItemsView?.SetValueFromRenderer(CarouselView.CurrentItemProperty, null);
	return 0;
}

@mattleibow, As per your suggestion, I have moved the logic into the GetPositionWhenAddingItems method for consistency.

What about KeepLastItemInView or KeepScrollOffset? Those also feel like candidates.

I found some Xamarin.Forms docs, so maybe just add this to the enum for now:

KeepItemsInView keeps the first item in the list displayed when new items are added.
KeepScrollOffset ensures that the current scroll position is maintained when new items are added.
KeepLastItemInView adjusts the scroll offset to keep the last item in the list displayed when new items are added.

@mattleibow, In CarouselView, the PreviousPosition is updated correctly for both KeepLastItemInView and KeepScrollOffset modes, so I added the condition only for the KeepItemsInView mode.

As per your suggestion, I have also added a summary for the ItemsUpdatingScrollMode enum.

Can we split this big condition?

Apply an early exit strategy:

const int InvalidPosition = -1;

// Early return for invalid positions - maintain current carousel position
if (currentItemPosition == InvalidPosition)
    return carouselPosition;

@jsuarezruiz, I have split the condition and updated the code to return the carouselPosition value earlier.

This suggestion is optional. These tests are a really good start, but could we include a few more?

• VerifyPositionUpdatesWhenRemovingCurrentItem
• VerifyPositionAfterBulkInsert (Add a Button in the sample to add several items at once)
• VerifyPositionAfterBulkRemove

@jsuarezruiz, In a scenario where ItemsUpdatingScrollMode is set to KeepItemsInView, inserting 5 items at the beginning of the list results in the previous position being 5 on Android and 1 on iOS.
Could you please confirm which behavior is correct?

Initial State:
Suppose we have items: [A, B, C, D, E]
Current position is at index 0 (item A)

Operation:
Insert 5 items at the beginning: [X1, X2, X3, X4, X5, A, B, C, D, E]
The current item (A) is now at index 5

Expected PositionChangedEventArgs:
PreviousPosition: 0 (original position of A)
CurrentPosition: 5 (new position of A)

Can you validate it?

@jsuarezruiz, Currently, when ItemsUpdatingScrollMode is set to KeepItemsInView and 5 items are added at the beginning [X1, X2, X3, X4, X5], the resulting collection becomes [X1, X2, X3, X4, X5, A, B, C, D, E].

PositionChangedEventArgs:
CurrentPosition: 0 (new position of X1)
PreviousPosition: 9 (original position of A)

This happens because the PositionChanged event is invoked for each item inserted.

Expected PositionChangedEventArgs:
CurrentPosition: 0 (new position of A)
PreviousPosition: 5 (original position of A)

What is the correct behavior in this scenario?

Could also validate more edge cases? Like, position bigger than ItemSource.Count.

Initial State:
Suppose we have items: [A, B, C, D, E]
Current position is at index 0 (item A)

Operation:
Insert 5 items at the beginning: [X1, X2, X3, X4, X5, A, B, C, D, E]
The current item (A) is now at index 5

Expected PositionChangedEventArgs:
PreviousPosition: 0 (original position of A)
CurrentPosition: 5 (new position of A)

Can you validate it?