Working with animation frame time in Jetpack Compose

AnimationClocks.kt

/**
 * Returns a [State] holding a local animation time in milliseconds.
 * The value always starts at `0L` and stops updating when
 * the call leaves the composition.
 */
@Composable
fun animationTimeMillis(): State<Long> {
    val millisState = state { 0L }
    val lifecycleOwner = LifecycleOwnerAmbient.current
    launchInComposition {
        val startTime = awaitFrameMillis { it }
        lifecycleOwner.whenStarted {
            while (true) {
                awaitFrameMillis { frameTime ->
                    millisState.value = frameTime - startTime
                }
            }
        }
    }
    return millisState
}

• launchInComposition is now LaunchedEffect(Unit)
• LifecycleOwnerAmbient is now LocalLifecycleOwner and has moved to a separate library
• awaitFrameMillis is now withFrameMillis
• whenStarted is now deprecated - replacement is withStarted
• The code inside the while block is now invalid because withStarted does not execute its context in a coroutine.