canvas-multiple-object.kt

val itemsToAnimate = remember {
    mutableStateOf<List<ItemState>>(mutableListOf())
}

val itemsChannel = remember {
    Channel<List<ItemState>>(Channel.UNLIMITED)
}
var job: Job? = remember {
    null
}

LaunchedEffect(true) {
    for (_items in itemsChannel) {
        job?.cancel()
        job = launch {
            withContext(Dispatchers.IO) {
                val items = _items.toMutableList()
                while (true) {
                    withFrameMillis {
                        val iterator = items.iterator()
                        var index = 0
                        val itemsToBeRemoved = mutableListOf<ItemState>()
                        while (iterator.hasNext()) {
                            val element = iterator.next() //element is ItemState
                            val elapsedTime = System.nanoTime() - element.startTime
                            val newX = element.xAnimation.getValueFromNanos(counter)
                            val newY = element.yAnimation.getValueFromNanos(counter)
                            items.safeSet(index) { 
                                it.copy(
                                    y = newY,
                                    x = newX,
                                )
                            }
                            index++
                            if (
                                itemState.terminalCondition(
                                    newX,
                                    newY
                                    (elapsedTime / 1_000_000).toFloat()
                                )
                            ) {
                                itemsToBeRemoved.add(itemState)
                            }
                        }
                        items.removeAll(itemsToBeRemoved)
                        hearts.value = items.toMutableList()
                    }
                    if (hearts.value.isEmpty()) {
                        job?.cancel()
                    }
                }
            }
        }
    }
}