// 参考: 1/60[s] ≒ 16.67[ms]
private const val S_PERIOD =  5L   //  5[ms]
//private const val S_PERIOD = 20L   // 20[ms]

class MainActivity : ComponentActivity() {
    @SuppressLint("CoroutineCreationDuringComposition")
    override fun onCreate(savedInstanceState: Bundle?) {
        super.onCreate(savedInstanceState)
        setContent {
            MyApplicationTheme {
                // countの変更を追跡
                var _count = remember { mutableStateOf(0) }
                Surface(
                    modifier = Modifier.fillMaxSize(),
                    color = MaterialTheme.colorScheme.background
                ) {
                    FramerateCheck(count = _count.value)
                }
                // 別スレッドでcountを更新
                val _coroutineScope = rememberCoroutineScope()
                _coroutineScope.launch(Dispatchers.Default) {
                    delay(5000)
                    repeat(100) {
                        _count.value++
                        delay(S_PERIOD)
                    }
                }
            }
        }
    }
}

private var prev_tim: Long = 0L
@Composable
fun FramerateCheck(count: Int) {
    // 周期の計測
    val _crrt_tim = System.currentTimeMillis()
    Log.i(TAG, "Period = ${_crrt_tim - prev_tim}[ms] (Count = ${count})")
    prev_tim = _crrt_tim
    // コンテンツの実態
    Text(text = "Count = ${count}")
}