I am trying to use `BottomSheetScaffold` and encou...

# compose

[Piotr Prus]

I am trying to use BottomSheetScaffold and encountered one problem. I do not know how to open the bottomSheet to certain value.
Example:
1. The view shows the list
2. User clicks the element in list
3. BottomSheet opens to certain height
4. User drags the sheet up
5. Sheet reveals to full screen
I tried to use BottomSheetScaffoldState.bottomSheetState.expand { }, but this function always open the sheet to full height. I was searching for something like: BottomSheetScaffoldState.bottomSheetState.expandByHalf() or BottomSheetScaffoldState.bottomSheetState.setAnchor(200.dp) or similar to this, but no luck.
Anyone knows how to make a mid step for BottomSheet?

[jossiwolf]

That's not supported by BottomSheetScaffold. There's ModalBottomSheet which has a HalfExpand state if the content is taller than 50% of the root element, so maybe that's what you're looking for?

[Piotr Prus]

Thanks for info. I saw how ModalBottomSheet is working. I am looking for something that will result in GoogleMaps behavior of bottomSheet. I guess this is a custom behavior with dynamic peekHeight or something.

[jossiwolf]

Makes sense! I don't think there's anything like that rn (except for setting the height of the sheet content manually, but that sucks)
Would be worth filing a feature request unless somebody knows anything!

[Piotr Prus]

I made a POC with dynamic peekHeight, bu then the slide down gesture is not working. 😞. I will try to hack the modalSheet

[julioromano]

@Piotr Prus I’m facing the same issue, did you manage to solve it?

[Piotr Prus]

Yes. I am using dynamic peekHeight.
Here is my column code (inside bottomSheet):

Column(
        modifier = Modifier
            .fillMaxWidth()
            .background(MaterialTheme.colors.primary)
            .verticalScroll(rememberScrollState())
            .pointerInput(Unit) {
                detectVerticalDragGestures(
                    onVerticalDrag = { change, dragAmount ->
                        if (dragAmount > 1f) onDragDown()
                    })
            }
    )

in onDragDown() I am calling:

changePeekHeight(0.dp)

Important thing to notice is that .pointerInput needs to be after Modifier.verticalScroll. If not, all the drag will be consumed by the scroll

[julioromano]

Is changePeekHeight() a Compose API ?

[Piotr Prus]

no, it is my own function in viewmodel that changes the peekHeight.
In Scaffold:

sheetPeekHeight = mapsViewState?.peekHeight ?: 0.dp,

in VM:

fun changePeekHeight(height: Dp) {
        mapsViewState.peekHeight = height
    }

[Saurabh Khare]

@Piotr Prus are you find the solution for BottomSheetState.expandByHalf(), I am also struggling with same. If you have sample code please share.

[Piotr Prus]

I do not have more than this. I build my own BottomSheet implementation that can be open at any height. That includes a lot of code. I do not have it on public repo 😞 . Maybe one day, but not now. Sorry.
Whan you need to do is make your own BottomSheetScaffold, copy the state functions, enums, etc and add your custom height to it.