rememberIsScrollingUpState.kt

rememberIsScrollingUpState.kt

@Composable
private fun LazyListState.rememberIsScrollingUpState(): State<Boolean> {
    var previousIndex by remember(this) { mutableIntStateOf(firstVisibleItemIndex) }
    var previousScrollOffset by remember(this) { mutableIntStateOf(firstVisibleItemScrollOffset) }

    return remember(this) {
        derivedStateOf {
            if (previousIndex != firstVisibleItemIndex) {
                previousIndex > firstVisibleItemIndex
            } else {
                previousScrollOffset >= firstVisibleItemScrollOffset
            }.also {
                previousIndex = firstVisibleItemIndex
                previousScrollOffset = firstVisibleItemScrollOffset
            }
        }
    }
}