Can I somehow access the total scroll amount from a `LazyListState`? I have a view drawn on top of a...

# compose-android

[MiSikora]

Can I somehow access the total scroll amount from a LazyListState? I have a view drawn on top of a LazyRow and I want to move it with the list scroll. Or maybe there is a better/alternative way to do it?

[Zach Klippenstein (he/him) [MOD]]

Knowing the total scroll amount would require knowing the total size of the content, which would defeat the purpose of lazy lists.

[MiSikora]

Isn't there some sort of a delta dispatch that could be accumulated?

[Zach Klippenstein (he/him) [MOD]]

Yes, if you know that the items won’t change size or be added/removed prior to the current position

[MiSikora]

So I'll need to write my own lazy scrollable composable for that, correct?

[Zach Klippenstein (he/him) [MOD]]

I think so? I don’t think you can just wrap LazyListState because you could miss windows if the scroll is happening too fast

[Zach Klippenstein (he/him) [MOD]]

If your items are all the same size, then you could calculate it just from the firstItemIndex

[Alex Vanyo]

What’s the usage of the LazyRow in this case? Are there going to be elements other than the tick marks that you’re scrolling through?

[MiSikora]

There are only tick marks but I'm also supporting zoom gesture for empty spaces with transformable() modifier so both item count and item width change.

[Alex Vanyo]

Got it, so each tick mark or group of tick marks is a different item?

[MiSikora]

Yes, they are timestamps in an audio file. Initially they are shown for every 5 seconds of an audio file and then users can use zoom gesture to increase or decrease the resolution.

[Alex Vanyo]

You might be able to avoid a Lazy container entirely, and have a component that is scrollable, zoomable, and manually draws the tick marks in that area based on the combination of scroll position and zoom - and then the overlay can be drawn based on the same information.

That might be a bit more setup, but you can avoid fighting with the LazyListState that way

[MiSikora]

I was thinking that as well. I started playing with today so LazyRow was my first idea for an implementation but it seems like I'm going against the grain so far.

In any case thank you both!