Compose - 부수효과_2

package kr.co.fastcampus.part1.chapter4_17

import android.graphics.Movie
import android.media.Image
import android.os.Bundle
import android.util.Log
import androidx.activity.ComponentActivity
import androidx.activity.compose.setContent

import androidx.compose.foundation.layout.Box
import androidx.compose.foundation.layout.Column
import androidx.compose.foundation.layout.fillMaxSize
import androidx.compose.foundation.lazy.LazyColumn
import androidx.compose.foundation.lazy.rememberLazyListState
import androidx.compose.material.*
import androidx.compose.runtime.Composable
import androidx.compose.runtime.DisposableEffect
import androidx.compose.runtime.LaunchedEffect
import androidx.compose.runtime.SideEffect
import androidx.compose.runtime.derivedStateOf
import androidx.compose.runtime.getValue
import androidx.compose.runtime.mutableStateListOf
import androidx.compose.runtime.produceState
import androidx.compose.runtime.remember
import androidx.compose.runtime.rememberCoroutineScope
import androidx.compose.runtime.rememberUpdatedState
import androidx.compose.runtime.snapshotFlow
import androidx.compose.ui.Modifier
import androidx.compose.ui.platform.LocalLifecycleOwner
import androidx.compose.ui.tooling.preview.Preview
import androidx.lifecycle.Lifecycle
import androidx.lifecycle.LifecycleEventObserver
import androidx.lifecycle.LifecycleObserver
import androidx.lifecycle.LifecycleOwner
import kotlinx.coroutines.flow.distinctUntilChanged
import kotlinx.coroutines.flow.filter
import kotlinx.coroutines.flow.map
import kotlinx.coroutines.launch
import kr.co.fastcampus.part1.chapter4_17.ui.theme.EffectTheme

class MainActivity : ComponentActivity() {
    override fun onCreate(savedInstanceState: Bundle?) {
        super.onCreate(savedInstanceState)
        setContent {
            EffectTheme {
                Surface(
                    modifier = Modifier.fillMaxSize(),
                    color = MaterialTheme.colors.background
                ) {
                    EffectEx()
                }
            }
        }
    }
}


@Composable
fun EffectEx(lifecycleOwner: LifecycleOwner = LocalLifecycleOwner.current) {
    val scaffoldState = rememberScaffoldState()

    // 단계 1: `LaunchedEffect`을 이용해서 스낵바를 이용해 봅시다.
    // 파라미터에는 `scaffoldState.snackbarHostState`를 전달합시다.
    // "헬로 컴포즈"라고 출력합시다.
    // `LaunchedEffect`는 `CouroutineScope`를 만들기 때문에 스코프를 별도로
    // 만들 필요는 없습니다.
    LaunchedEffect(scaffoldState.snackbarHostState) {
        scaffoldState.snackbarHostState.showSnackbar("헬로 컴포즈. 패스트 캠퍼스")
    }
    // 단계 2: `DisposableEffect`를 호출하고 파리미터로 `lifecycleOwner`를
    // 전달합니다.

    // `LifecycleEventObserver`를 상속받고 두 상태에 대해 로그를 남깁니다.
    // `Lifecycle.Event.ON_START`, `Lifecycle.Event.ON_STOP`

    // 블록 내에서 `lifecycleOwner.lifecycle.addObserver`로 옵저버를 추가하고
    // onDispose에서 옵저버를 제거합니다.
    DisposableEffect(lifecycleOwner) {
        val observer = LifecycleEventObserver { _, event ->
            // sam : single abstract method
            when (event) {
                Lifecycle.Event.ON_START -> Log.d("lifeCycle", "onStart")
                Lifecycle.Event.ON_STOP -> Log.d("lifeCycle", "onStop")
                Lifecycle.Event.ON_PAUSE -> Log.d("lifeCycle", "onPause")
                Lifecycle.Event.ON_RESUME -> Log.d("lifeCycle", "onResume")
                else -> Log.d("lifeCycle", "그 외")
            }
        }
        lifecycleOwner.lifecycle.addObserver(observer)
        onDispose {
            lifecycleOwner.lifecycle.removeObserver(observer)
        }
    }

    Scaffold(
        scaffoldState = scaffoldState
    ) {
    }
}

@Preview(showBackground = true)
@Composable
fun DefaultPreview() {
    EffectTheme {
        EffectEx()
    }
}