Google Maps Wont restoreState properly when navigating through bottom nav

[renzified]

Environment details

1. library: com.google.maps.android:maps-compose:2.1.0

Steps to reproduce

1. clone this repo
2. add your google api key to the manifest file
3. Quickly navigate between the bottom tabs and check if the maps is loaded properly
4. When navigating quickly with the bottom tabs the maps wont restore its state eg. camera position, markers

Observation

The maps will load properly even if we navigate quickly on the bottom tabs when the starting route of nav host is the map to reproduce.

1. Change the AnimatedNavHost start destination from

AnimatedNavHost(
         navController = navController,
         startDestination = Screen.Other.route
     )

to

AnimatedNavHost(
            navController = navController,
            startDestination = Screen.Map.route
        )

and it will work just fine.

Here is a sample video of the bug

[jpoehnelt]

@thekingrenz23 Thank you for opening this issue. 🙏
Please check out these other resources that might be applicable:

• Support Console - If you have a support contract.
• Discord - chat with other developers
• StackOverflow - use the google-maps tag
• Google Maps Platform issue trackers

This is an automated message, feel free to ignore.

[renzified]

Still no upadate on this one?

[arriolac]

I can confirm the bug—thanks for reporting @thekingrenz23. The bug isn't immediately obvious so will need to do add some additional logging to pinpoint the issue.

[arriolac]

I tested a different scenario where a button toggles a mutableStateOf boolean that brings the GoogleMap composable in and out of composition. Quickly tapping the button doesn't produce the same bug and so it looks like the issue is specific to the GoogleMap being used within a BottomNavigation composable (along with the specific config you have set up in your sample).

[PiotrPrus]

You can reduce the occurrence of this error by omitting the default cross-fade transition for navHost. You can do this using : https://google.github.io/accompanist/navigation-animation/
here is the snipped:
AnimatedNavHost( navController = navController, startDestination = "home", enterTransition = { EnterTransition.None }, exitTransition = { ExitTransition.None } )

[renzified]

hmmm I tried it with the default NavHost with no animation capability and still happens so it must not be the animation I guess?

[PiotrPrus]

The default NavHost has a crossfade animation built in.

[renzified]

Removing the animation is not an option for my project

[arriolac]

Looks like this issue happens you're in the tab displaying the map, and quickly tap out and back in (before the crossfade animation completes). In this specific scenario, the MapView is in the state such that the GoogleMap composable never left the composition (and so nodes aren't readded) but the MapView has been recreated (i.e. went through an ON_STOP, followed by an ON_CREATE > ON_START > ON_RESUME). I believe the fix here would be to propagate the saved instance state Bundle across the various MapView lifecycle events. However, there are no hooks in the androidx.lifecycle library to obtain that bundle. Will try to figure out a workaround for this.

Edit: saving instance state will only restore some properties of the map (like the camera's position). Drawn objects like markers will have to be readded. The closest thing to a workaround for now is to shorten the crossfade duration to reduce the occurrence of this bug.