Is it possible to synchronize the `LazyListState` ...

# compose

[Zoltan Demant]

Is it possible to synchronize the LazyListState (scroll position) between multiple LazyRow? Ive tried using one rememberLazyListState but that results in weird scrolling glitches; Im sort of assuming that Ill need to collect all scroll events and update each LazyListState?

[cb]

LazyListState contains all of the layout state for its host component, so it can only really be used in a single LazyColumn, etc.

I wouldn’t mess around with touch input here. I’d use a LaunchedEffect to read the first visible item + offset on each LazyListState, then call scrollToItem to coordinate the others.

You might need to gate the changes on isScrollInProgress to stop any recursion loops.

[Zoltan Demant]

Thanks Chris, Ill try that when I get back to working on this feature! 👍🏽

[Zoltan Demant]

Aaand it works! 🙂 Thanks again.

val listControllers = remember {
    mutableStateMapOf<ChartType, ListController>()
}

LaunchedEffect(listControllers) {
    val controllers = listControllers.values

    snapshotFlow {
        controllers
            .firstOrNull(ListController::scrollInProgress)
            ?.let { controller ->
                val index = controller.firstVisibleItemIndex()
                val scrollOffset = controller.firstVisibleItemScrollOffset()
                index to scrollOffset
            }
    }
        .filterNotNull()
        .distinctUntilChanged()
        .collect { (index, scrollOffset) ->
            controllers.forEach { controller ->
                if (!controller.scrollInProgress()) {
                    controller.scrollTo(
                        index,
                        scrollOffset
                    )
                }
            }
        }
}

[cb]

Very nice! Glad it worked 😅

[cb]

@Andrey Kulikov in case there’s a better way