Can `HorizontalPager` support circular swiping somehow?

# compose

[Peter]

Can HorizontalPager support circular swiping somehow?

[Garret Yoder]

Yeah, you can supply it with whatever data you want, its just giving you an index to load from.

[Garret Yoder]

Set the page count to like Int.MAX_VALUE or something really big, and then get your 'actual page' by division remainder

[Garret Yoder]

pagerStatePage % listSize

[Garret Yoder]

You can do the same thing with the indicator. Indicator max size = list size, and the current page the same as above. This will give you infinite scroll where when you scroll from the last item, it will loop back to index 0

[Peter]

But how do you make this work in negative index direction? Like if you're on index 0 and you try to swipe to index -1.

From HorizontalPager API, I don't see how would this be achievable, since it looks like it is managing page index for you.

[Garret Yoder]

start the initial page at Int.MAX_VALUE / 2

[Garret Yoder]

and then round it down so your 'real page' ends up being zero in that remainder div

[Garret Yoder]

that way you have an unreachable number before and an unreachable number after your index.

[Garret Yoder]

or just start it at like list.size*1000 or something. Just pick a really big number and you should be fine

[Garret Yoder]

remember with the modulus the 'page' that the state object is tracking is irrelevant, because you're just feeding it a bogus value for it to swipe left and right, and then you're actually rendering the remainder of that division against the list size, which will just be 0 -> list.size and will wrap back and fourth in either direction

[Garret Yoder]

@OptIn(ExperimentalFoundationApi::class)
@Composable
fun InfiniteHorizontalPager(modifier: Modifier = Modifier, size: Int, content: @Composable (page: Int) -> Unit) {
    val pagerState = rememberPagerState(
        pageCount = { size*100000 },
        initialPage = size*50000
    )
    HorizontalPager(modifier = modifier, state = pagerState) { page ->
        content(page%size)
    }
}

There, that will do it. Pager's state didn't like Int.MAX_VALUE, so I jsut picked a large number (100k pages) that no user will ever scroll through.