[navigator-animation] `popEnterTransition` drawn on top of `popExitTransition`

Describe the bug

In navigator-animation when I pop a NavBackStackEntry off the graph and the popExitTransition and popEnterTransition is called the destinations popEnterTransition is drawn over the current (popping) entry’s popExitTransition.

To Reproduce

Construct an AnimatedNavHost with a customized popEnterTransition that has an initial offset > 0, e.g.

AnimatedNavHost(
  navController, 
  startDestination = "Blue",
  popEnterTransition = { _, _, ->
    slideInHorizontally(initialOffsetX = { -it / 5 }, animationSpec = tween(durationMillis = 700))
  }
)

NOTE: If modifying the AnimatedNavHostSample make sure to null out the popEnterTransition of the destination composable, I updated the “Blue” composable to popEnterTransition = null

Expected behavior

The popEnterTransition for the destination NavBackStackEntry should be drawn underneath (lower z-index) the popExitTransition of the current NavBackStackEntry during a pop.

Screenshots?

Environment:

• Android OS version: [Android 10]
• Device: [Emulator]
• Accompanist version: [0.18.0]

[ThomasArtProcessors]

Same issue, which is especially jarring when screens slide up and down. I have a screen that should remain in place with another sliding up from the bottom then sliding down when exiting, but the main screen just appears directly so the slide down is lost.

[maurycyw]

@jbw0033

could this be as simple as specifying the targetContentZIndex when specifying the transitionSpec for the AnimatedContent? :

meaning instead of

transition.AnimatedContent(
    modifier,
    transitionSpec = { finalEnter(this) with finalExit(this) },
    contentAlignment
) { ... }

we could do:

transition.AnimatedContent(
    modifier,
    transitionSpec = { ContentTransform(finalEnter(this), finalExit(this), 1f) },
    contentAlignment
) { ... }

Also can this ticket please be reopened