Is it possible to get scroll offset in pixels for `LazyColumn`? Can only see `firstVisibleItemScroll...

# compose

[Jason Ankers]

Is it possible to get scroll offset in pixels for LazyColumn? Can only see firstVisibleItemScrollOffset which is relative to items in the list

[Albert Chang]

The point of lazy lists is that they lay out items lazily so that only items currently visible are laid out, which means heights of invisible items are unknown.

[Jason Ankers]

How could I achieve a fading background as the user scrolls down a list?

[Albert Chang]

What do you mean by fading background?

[Jason Ankers]

I mean adjust the alpha of a background colour gradually as the user scrolls down a list

[Albert Chang]

Use item index then. I don’t think laying out all items is worth as it is much less performant.

[Jason Ankers]

That only works if all the items are the same size

[Albert Chang]

I know you can’t make the fade completely linear by using index, but as I said,

I don’t think laying out all items is worth as it is much less performant.

[Albert Chang]

If you really want to try, just use a scrollable column and see how much it is slower than LazyColumn.

[Jason Ankers]

I don’t understand why losing virtualization is a requirement for tracking scroll offset? We had this functionality previously in our react native app which caches item heights as you scroll past them

[Albert Chang]

What do you mean by virtualization? If you just want to know the heights of items you scrolled past, you can do the same thing.

[Jason Ankers]

Yeah it was more a question if theres anything out the box

[Albert Chang]

I think no.

[joney]

Maybe it helps:
https://developer.android.com/reference/kotlin/androidx/compose/ui/input/nestedscroll/package-summary#(androidx.compose.ui.Modifier).nestedScroll(androidx.compose.ui.input.nestedscroll.NestedScrollConnection,androidx.compose.ui.input.nestedscroll.NestedScrollDispatcher)

[Andrey Kulikov]

yes, it is expected to solve use cases like this with the nested scroll apis. but we don’t have good official examples yet as far as I remember