A `LifecycleOwner` that can switch between mirroring of its parent's state and an overridden state

mirroringLifecycleOwner.kt

import androidx.compose.runtime.Composable
import androidx.compose.runtime.DisposableEffect
import androidx.compose.runtime.Immutable
import androidx.compose.runtime.remember
import androidx.lifecycle.Lifecycle
import androidx.lifecycle.LifecycleEventObserver
import androidx.lifecycle.LifecycleOwner
import androidx.lifecycle.LifecycleRegistry
import androidx.lifecycle.compose.LocalLifecycleOwner

@Composable
fun mirroringLifecycleOwner(mode: LifecycleMirrorMode): LifecycleOwner {
  val hostLifecycle = LocalLifecycleOwner.current.lifecycle
  val mirroringOwner = remember(hostLifecycle) {
    object : LifecycleOwner {
      val lifecycleRegistry = LifecycleRegistry(provider = this)
      override val lifecycle: Lifecycle get() = lifecycleRegistry
    }
  }
  DisposableEffect(mode, hostLifecycle) {
    val observer = LifecycleEventObserver { _, event ->
      val nextState = mode.choose(hostState = event.targetState)
      mirroringOwner.lifecycleRegistry.currentState = nextState
    }
    hostLifecycle.addObserver(observer)
    onDispose { hostLifecycle.removeObserver(observer) }
  }
  return mirroringOwner
}

@Immutable
sealed interface LifecycleMirrorMode {
  data object MirrorParent : LifecycleMirrorMode
  data class Override(val withState: Lifecycle.State) : LifecycleMirrorMode

  fun choose(hostState: Lifecycle.State): Lifecycle.State {
    return if (hostState == Lifecycle.State.DESTROYED) {
      hostState
    } else {
      when (this) {
        is MirrorHost -> hostState
        is Override -> if (hostState.isAtLeast(withAtMost)) withAtMost else hostState
      }
    }
  }
}

Usage:

val pagerState = rememberPagerState(...)

HorizontalPager(pagerState) { pageNum ->
  val pageLifecycleOwner = mirroringLifecycleOwner(
    mirrorMode = when (pagerState.settledPage) {
      pageNum -> LifecycleMirrorMode.MirrorParent
      else -> LifecycleMirrorMode.Override(Lifecycle.State.CREATED)
    }
  )
  CompositionLocalProvider(LocalLifecycleOwner provides pageLifecycleOwner) {
    // Your pages here.
  }
}