Can someone share insights on how to use `rememberLazyListSt

Question

Can someone share insights on how to use `rememberLazyListState` with `LazyColumn` for a chat interface JetChat in `compose samples` still uses `ScrollableColumn` so it doesn t help much especially in these areas How do we smooth scroll to show a new incoming message Since we only have relative based `smoothScrollBy` instead of `smoothScrollTo 0f ` on `reverseLayout = true` it s hard to get to the right spot and `snapToIndex 0 ` is unnatural How do we get measurements of the specific message component sizes to make the right relative scrolling calculation I ve seen `chatScrollState layoutInfo visibleItemsInfo` but i m not sure how to get updates when `layoutInfo` changes sticking it inside `LaunchedEffect` doesn t fire How do we know when we are getting to the end of the `LazyColumn` so that we can fetch older messages and add them to the list In the case where new messages are coming in or old messages are being added how do we maintain existing scroll position without the whole list jumping around

Sam · Answer

cc < Andrey Kulikov>

Dominaezzz · Answer

I also happen to be interested in this too and have implement some

Dominaezzz · Answer

For the 3rd point you can use `onActive onDispose ` on the oldest or whatever you feel is right item in the `LazyColumn` to trigger the fetch

Dominaezzz · Answer

For the second point try using a `snapshotFlow ` to capture the changes

Dominaezzz · Answer

For the first point it s a relatively new feature so I m not sure In theory you can use keep calling `smoothScrollBy` until you re at the bottom of the list aha

Dominaezzz · Answer

For the last point when I get new messages I don t experience this jumping you describe

Sam · Answer

< Dominaezzz> good suggestion to support infinite scroll i will try adding logic to `onActive` to detect when to fetch

Sam · Answer

< Dominaezzz> are you using reverseLayout = true If so how do you show new messages that just arrived `snapToIndex` or `smoothScrollBy`

Dominaezzz · Answer

I am indeed using `reverseLayout = true` new messages tend to just show up without me having to scroll Although if there s a tiny bit of scroll it doesn t show up Haven t gotten to that yet

Sam · Answer

but do they smooth scroll or they just snap and appear

Dominaezzz · Answer

It s a snap I m pretty sure most messengers do this though

Sam · Answer

i don t know about android but there isn t a single one on iOS that snaps

Dominaezzz · Answer

Fascinating Slack snaps

Dominaezzz · Answer

Unless you re on iOS now lol

Sam · Answer

most chat apps snap on desktop but not on iOS

Andrey Kulikov · Answer

`smoothScrollToItem` is still in progress so not yet ready we also don t yet have a solid support for item animations you can implement something on your own with tools like `AnimatedVisibility` but not everything