Jetpack Compose scrolling LazyColumn with CoroutineScope results error A MonotonicFrameClock is not available in this CoroutineContext

Question

Checking out this example with list to scroll using state and Coroutines as

@Composable
fun ScrollingList() {
    val listSize = 100
    // We save the scrolling position with this state
    val scrollState = rememberLazyListState()
    // We save the coroutine scope where our animated scroll will be executed
    val coroutineScope = rememberCoroutineScope()

    Column {
        Row {
            Button(onClick = {
                coroutineScope.launch {
                    // 0 is the first item index
                    scrollState.animateScrollToItem(0)
                }
            }) {
                Text("Scroll to the top")
            }

            Button(onClick = {
                coroutineScope.launch {
                    // listSize - 1 is the last index of the list
                    scrollState.animateScrollToItem(listSize - 1)
                }
            }) {
                Text("Scroll to the end")
            }
        }

        LazyColumn(state = scrollState) {
            items(listSize) {
                ImageListItem(it)
            }
        }
    }
}

Which works fine for suspending function

suspend fun animateScrollToItem(
    /*@IntRange(from = 0)*/
    index: Int,
    /*@IntRange(from = 0)*/
    scrollOffset: Int = 0
) {
    doSmoothScrollToItem(index, scrollOffset)
}

If i change coroutine scope to

val coroutineScope = CoroutineScope(Dispatchers.Main)

It returns

java.lang.IllegalStateException: A MonotonicFrameClock is not available in this CoroutineContext. Callers should supply an appropriate MonotonicFrameClock using withContext.

What does this mean, and is rememberCoroutineScope() only way to provide coroutineScope to this function?

@ianhanniballake not because i would not use it, just curios what that error is about and if there are any other ways to provide **coroutineScope**? — Thracian, Jul 15 '21 at 17:35

score 12 · Accepted Answer · answered Jul 19 '21 at 07:40

As animateScrollToItem is composable function it needs to be called within the scope of Composition.

As documentation states

rememberCoroutineScope is a composable function that returns a CoroutineScope bound to the point of the Composition where it's called. The scope will be cancelled when the call leaves the Composition.

Jetpack Compose scrolling LazyColumn with CoroutineScope results error A MonotonicFrameClock is not available in this CoroutineContext

1 Answers1

Linked