What is the right way to get a callback when a `Mo...

# compose

[Bryan Herbst]

What is the right way to get a callback when a ModalBottomSheetLayout is dismissed, either from accessibility actions or from tapping on the scrim outside the sheet?

Drop a DisposableEffect inside the sheet’s content? I don’t see any sort of callback or observable state.

[KoskiA]

Yeah, I ran into the same issue with swipeable() in my dev challenge. I used a LaunchedEffect : https://github.com/dandc87/Compose-Challenge-Puppies/blob/de067d272b4c7c41df6c4856[…]7123/app/src/main/java/com/dandc87/fetch/SwipeableCardLayout.kt

[Bryan Herbst]

I like the LaunchedEfffect approach- that would support getting a callback for half expanded and fully expanded states as well.

Both that and DisposableEffect feel a little weird, but that might just be me getting used to the declarative UI paradigm

[matvei]

the closure of the ModalSheet is an event you can observe. If you want to trigger a side effect when happens (which is why you are reaching out for a callback probably, right?) you can do it via DisposableEffect or LaunchedEffect, if you need a scope:

val state = rememberModalBottomsheetState(BottmsheetValue.Expanded)
DisposableEffect(state.isClosed) {
    //this is called when state.isClosed changed during last composition, so you can trigger a side effect when you want (true or false)
    onDispose { /* cleanup here */}
}

ModalBottomSheetLayout(state, ....)

[Bryan Herbst]

Thanks! A side effect is exactly what I’m thinking, for example sending analytics events.

[matvei]

So this tools will suit your case perfectly then 🙂