How to you keep the value of

state { ... }

across configuration changes?

I think using the saved state registry should help, i.e. use

savedInstanceState {}

instead of

state {}

Substitute

state {}

for

savedInstanceState {}

ohh i see thank you :D

why are those two different thing? Is there a benefit choosing

state

over

savedInstanceState

?

savedInstanceState

has the usual restrictions. You can’t put big objects there and you’ll have to parcel/serialize them

Once you get into the discussion of, "yes but what about ViewModels? Those don't need to parcel!" you also get into the property of config changes where you commonly rearrange the UI shape in those different configurations and the API has to again account for different things. Compose doesn't know which parts of a very different composition shape are semantically equivalent and how to key them without your help.

A different question, could compose has its own rotation state independent from activity? Is this possible, having portrait locked activity and letting compose to handle rotation?

Camera apps more or less do that but it would have a lot of side effects affecting a lot of view interop. There's nothing stopping one from trying it, really. If you're looking primarily to preserve state, marking the host activity as handling its own configuration changes is probably a less disruptive path.

I will definitely experiment with transition for this, Just to check if having smooth rotation is possible 😄

aha, thanks @Ian Lake for finding the other magic flag: https://developer.android.com/reference/android/view/WindowManager.LayoutParams#ROTATION_ANIMATION_SEAMLESS