为什么导航回到屏幕然后向上/向下滑动或单击后，下拉刷新框会消失？

Question

我正在开发一个 Jetpack Compose 应用程序，该应用程序实现了 Material3 新的拉动刷新 (PullToRefreshBox) 功能。但是，我遇到了一个问题，即导航回屏幕或向上/向下滑动屏幕后，下拉刷新框消失了。

我面临的问题： 拉动刷新指示器消失：当我离开此屏幕然后返回时，滚动屏幕或单击屏幕，拉动刷新指示器在刷新任务正在进行时立即消失。

向上/向下滑动时的行为：此外，当我向上或向下滑动时，下拉刷新指示器会意外消失。

@AndroidEntryPoint
class TestActivity : ComponentActivity() {

    override fun onCreate(savedInstanceState: Bundle?) {
        super.onCreate(savedInstanceState)
        setContent {
            MyApp()
        }
    }
}

@Composable
fun MyApp() {
    // Define the routes and their respective icons
    val topLevelRoutes = listOf(
        TopLevelRoute("Profile", "profile", Icons.Filled.AccountCircle),
        TopLevelRoute("Friends", "friends", Icons.Filled.People)
    )

    // Create a NavController
    val navController = rememberNavController()

    Scaffold(
        bottomBar = {
            BottomNavigation {
                val navBackStackEntry by navController.currentBackStackEntryAsState()
                val currentDestination = navBackStackEntry?.destination
                topLevelRoutes.forEach { topLevelRoute ->
                    BottomNavigationItem(
                        icon = {
                            Icon(
                                topLevelRoute.icon,
                                contentDescription = topLevelRoute.name
                            )
                        },
                        label = { Text(topLevelRoute.name) },
                        selected = currentDestination?.route == topLevelRoute.route,
                        onClick = {
                            navController.navigate(topLevelRoute.route) {
                                popUpTo(navController.graph.findStartDestination().id) {
                                    saveState = true
                                }
                                launchSingleTop = true
                                restoreState = true
                            }
                        }
                    )
                }
            }
        }
    ) { innerPadding ->
        NavHost(navController, startDestination = "profile", Modifier.padding(innerPadding)) {
            composable("profile") { ProfileScreen() }
            composable("friends") { FriendsScreen() }
        }
    }
}

data class TopLevelRoute(val name: String, val route: String, val icon: ImageVector)

@OptIn(ExperimentalMaterialApi::class, ExperimentalMaterial3Api::class)
@Composable
fun ProfileScreen() {

    var isRefreshing by rememberSaveable { mutableStateOf(false) }

    // Launch an effect when refreshing starts
    if (isRefreshing) {
        LaunchedEffect(Unit) {
            delay(10000) // Simulate a network call
            isRefreshing = false // Reset refreshing state
        }
    }

    // Content for the Profile screen
    Surface {
        PullToRefreshBox(
            onRefresh = { isRefreshing = true },
            isRefreshing = isRefreshing,
            modifier = Modifier
                .fillMaxSize()
        ) {
            Column(
                modifier = Modifier
                    .fillMaxSize()
                    .verticalScroll(rememberScrollState()),
                verticalArrangement = Arrangement.Center,
                horizontalAlignment = Alignment.CenterHorizontally,

                ) {
                // Your main content here
                Text("Profile Screen", style = MaterialTheme.typography.h4)
            }
        }
    }
}

@Composable
fun FriendsScreen() {
    // Content for the Friends screen
    Box(modifier = Modifier.fillMaxSize(), contentAlignment = Alignment.Center) {
        Text("Friends Screen")
    }
}

Answer 1

这是material3当前稳定版本中的一个bug。它已经在当前的 alpha 版本 1.4.0-alpha02 中得到修复，我认为通过 this 提交。