dispose steps after transition

[shpasha]

ISSUE SOLVED: 106

There is a problem. Let's take a look at the sample code.

If we set disposeStepsBehavior = DisposeStepsBehavior.DisposeWhenStackChanged in my sample, then when navigating to the SampleScreen#1 and going back, ViewModel on the SampleScreen#1 will be recreated because of transition and work will go on in it.

Also there is another problem. Suppose we use screenModel instead of viewModel. If we navigate back from the SampleScreen#1 and, without waiting for the transition to complete, navigate back to the SampleScreen#1, screenModel will be recreated, I expect the screenModel to be destroyed only after the screen has become invisible to the user and disappeared from the stack.

upd.

So, i've created 2 sample activities: DisposeWhenStackChangedSampleActivity, DisposeWhenTransitionFinishedSampleActivity.

• DisposeWhenStackChangedSampleActivity. Just open it, then click Next, on the next screen click Back. You can see in logcat, that Doing job is still printing.
• DisposeWhenTransitionFinishedSampleActivity. Same steps, but everything works correctly

[shpasha]

Also we can get rid of StepDisposableEffect. And emit transition finished events also in CurrentScreen method:

@Composable
public fun CurrentScreen() {
    val navigator = LocalNavigator.currentOrThrow
    val currentScreen = navigator.lastItem
    val transitionFinishedEvents = LocalTransitionFinishedEvents.current

    LaunchedEffect(currentScreen) { transitionFinishedEvents.trySend(Unit) }
    navigator.saveableState("currentScreen") {
        currentScreen.Content()
    }
}

[DevSrSouza]

I have built another solution that is easier and does not change the Voyager core api and let the Transition api do all the work.

#436