What's the approach in Compose when you have a bot...

# compose

[Florian]

What's the approach in Compose when you have a bottom nav hosted in the activity but want a full-screen screen in some destinations? Just hide the bottom nav through a callback + a state variable? I'm worried if this could get out of sync somehow.

[Stepan Furman]

You can check is it necessary to show bottom bar by route of currentBackStackEntry's destination, where currentBackStackEntry is state:

val currentBackStackEntry by navController.currentBackStackEntryAsState()

[Stepan Furman]

It must be in sync, otherwise it's a bug in navigation component

[Florian]

alright, thank you

[Florian]

Hm looks like this is the wrong approach because recreateing the BottomNavigation will lose its state

[Florian]

but I wanna keep the backstack and scroll positions intact

[Stepan Furman]

check it https://github.com/Furman111/BooksExplorer/blob/main/app/src/main/java/ru/furman/booksexplorer/navigation/AppContent.kt

[Florian]

you're using AnimatedVisibility

[Florian]

that's pretty clever

[Florian]

This way it shouldn't lose the state

[Florian]

no it actually does lose scroll position

[Florian]

I'm running your app

[Stepan Furman]

It's because of paging library bug/behavior 😞

[Stepan Furman]

With common lazy list it works perfectly

[Stepan Furman]

Check with scroll state of carousel

[Florian]

hm weird

[Florian]

I have the same setup but I lose LazyColumn scroll position if I add AnimatedVisibility

[Stepan Furman]

Possibly you should hoist up your lazy list state to root level of your Composable, check https://github.com/Furman111/BooksExplorer/blob/6e7d898922568c90e3bbfc3f553ba4b4ee[…]app/src/main/java/ru/furman/booksexplorer/ui/main/MainScreen.kt

[Florian]

Indeed, that fixed it

[Florian]

Wow, thank you so much

[Florian]

although I don't yet understand why it works like this

[Florian]

Jetpack Compose is definitely tricky

[Stepan Furman]

Read https://developer.android.com/jetpack/compose/state

[Florian]

I already read that but I guess I should read it again 😂

[Florian]

But it looks really great like this. You made my day 👍

[Stepan Furman]

Also this codelab helped me to get state in compose - https://developer.android.com/codelabs/jetpack-compose-state

[Florian]

yea I worked through that as well too

[Florian]

but it's tricky to really understand

[Florian]

at least the rememberLazyListpart

[Florian]

btw there is also a bug in the bottom nav code from the docs

[Florian]

are you aware of that?

[Stepan Furman]

About double taps?

[Stepan Furman]

Yeah, hope it'll be fixed soon

[Stepan Furman]

Maybe in stable release, it's alpha now

[Florian]

right

[Florian]

Do you think wrapping the bottom nav item's onClick with

if (currentDestination?.route != destination.route)

fixes this?

[Florian]

it seems to work

[Stepan Furman]

It works, but if you gonna add behavior of poping your backStack to startDestination (if you click on bottom bar item that is already selected) - it has to be refactored later (

[Stepan Furman]

It seems common pattern in apps

[Florian]

yea that's true

[Colton Idle]

@Florian if you search this channel Ian lake has discussed this very thing like 20 times in the past few months 😄