Is there a way to check if a `LazyColumn`s `stickyHeader` is currently sticking? Edit: I made a `Mod...

# compose

[Alex]

Is there a way to check if a `LazyColumn`s stickyHeader is currently sticking?
Edit: I made a Modifier myself, code in 🧵

[Alex]

This works great:

/**
 * Will elevate the composable if it's sticking to the top of the parent.
 * Used for drawing shadows on sticky headers when they are at the top.
 */
@Composable
fun Modifier.showShadowIfStickingToTop(
    topElevation: Dp = 4.dp,
    elevationTransitionLabel: String = "elevate-if-at-top-transition",
): Modifier {
    var isAtTop by rememberSaveable { mutableStateOf(false) }
    val elevationDp by animateDpAsState(
        if (isAtTop) topElevation else 0.dp,
        label = elevationTransitionLabel,
    )
    return onPlaced { layoutCoordinates ->
        with(layoutCoordinates) {
            val parentRootOffsetY =
                (parentLayoutCoordinates?.localToRoot(Offset.Zero) ?: Offset.Zero).y
            val ownRootOffset = localToRoot(Offset.Zero).y
            val topOffset = ownRootOffset - parentRootOffsetY
            isAtTop = topOffset == 0f
        }
    }.shadow(elevationDp)
}

[Stylianos Gakis]

You probably want to turn this into a modifier using composed { right?
An extension on modifier also being a composable itself looks odd, never seen it before tbh.

[sindrenm]

I think @Composable fun Modifier.foo() is recommended now instead of using composed {}.

https://developer.android.com/develop/ui/compose/custom-modifiers#create_a_custom_modifier_using_a_composable_modifier_factory

[Stylianos Gakis]

I feel like an ancient person, giving old advice 😂
Thanks a lot Sindre!

[sindrenm]

I mean, they did recommend replacing @Composable fun Modifier.foo() with composed {} in the past, so it's been kind of a bit back and forth. But anytime! 😀

[Alex]

Maybe @Stylianos Gakis is way ahead of us, since google will recommend replacing composable fun with composed in the near future again 😄

[sindrenm]

Only time will tell, although I think we're supposed to use Modifier.Node stuff when possible. 😅