BottomSheet: Consider adding keys to rememberBottomSheetState

[leononame]

My use case is relatively simple: I would like to get a bottom sheet that jumps to a specific height based on the content on the screen. However, that content can be dynamic, so I would like the seet size to be dynamic as well.

Take this example:

@Composable
fun TestScreen(accountId: AccountId) {
    // make a big box
    Box(Modifier.fillMaxSize().safeContentPadding().background(Color.Gray)) {
        // measured size of the content
        var contentSize by remember { mutableStateOf(IntSize.Zero) }
        // measured height is derived from the size
        val contentHeight = with(LocalDensity.current) { contentSize.height.toDp() }

        // draw a box that grows by 100.dp every time it's clicked
        var height by remember { mutableStateOf(100.dp) }
        Box(
            Modifier
                .height(height)
                .fillMaxWidth()
                .background(Color.Red)
                .clickable { height += 100.dp }
                // measure size of the box
                .onSizeChanged { contentSize = it }) {}

        // create detents
        // peek should be 50.dp below the box above
        val peek = SheetDetent(identifier = "peek") { containerHeight, _ ->
            // contentHeight is captured here, but because rememberBottomSheetState remembers it from the first time
            // the scrim was created, it's not updated
            println("calling peek with content height: $contentHeight")
            containerHeight - contentHeight - 50.dp
        }
        // fullscreen should go above the box to 90% of the content size
        val fullScreen = SheetDetent(identifier = "fullscreen") { containerHeight, _ ->
            containerHeight * 0.9f
        }
        // make sheet
        val sheetState = rememberBottomSheetState(
            detents = listOf(peek, fullScreen),
            initialDetent = peek,
        )
        BottomSheet(
            state = sheetState,
            modifier = Modifier.fillMaxWidth().background(Color.White),
        ) {
            Column(
                modifier = Modifier.fillMaxWidth(),
                horizontalAlignment = Alignment.CenterHorizontally,
            ) {
                DragIndication(
                    Modifier
                        .padding(top = 22.dp)
                        .background(Color.Black.copy(0.4f), RoundedCornerShape(100))
                        .width(32.dp)
                        .height(4.dp)
                )
                LazyColumn {
                    repeat(50) {
                        item { Text("Item #${(it + 1)}", modifier = Modifier.padding(10.dp)) }
                    }
                }
            }
        }

    }
}

The problem is that when I specify detents, their lambdas capture values during the first run and won't re-trigger afterwards. It would be nice if it was possible to force the sheetState to recalculate on specific keys, in this case e.g. contentHeight.

I would have implemented my own rememberBottomSheetState, but since the SheetState constructor is internal, I can't.

[alexstyl]

Thanks for the request. Sounds very reasonable.

I'm currently busy with some other project and once that is sorted, I will be able to work on unstyled again. Can't promise on dates.