Android Weekly Notes #465

Android Weekly Issue #465

Learning Live Templates for Jetpack Compose

如何创建live templates.

一个有用的快捷键: alt + cmd + j.
会弹出来让你选择包围控件.

Jetpack Compose的一些有用的live templates.

Bottom Navigation and Navigation Drawer Using Scaffold from Jetpack Compose

这个例子既有BottomNavigation又有侧面的Drawer.

ViewModel记住了当前Screen:

class MainViewModel : ViewModel() {

    private val _currentScreen = MutableLiveData<Screens>(Screens.DrawerScreens.Home)
    val currentScreen: LiveData<Screens> = _currentScreen

    fun setCurrentScreen(screen: Screens) {
        _currentScreen.value = screen
    }
}

BottomBar的部分:

@Composable
fun BottomBar(modifier: Modifier = Modifier, screens: List<Screens.HomeScreens>, navController: NavController) {
    BottomNavigation(modifier = modifier) {
        val navBackStackEntry by navController.currentBackStackEntryAsState()
        val currentRoute = navBackStackEntry?.arguments?.getString(KEY_ROUTE)
        screens.forEach { screen ->
            BottomNavigationItem(
                icon = { Icon(imageVector = screen.icon, contentDescription = "") },
                label = { Text(screen.title) },
                selected = currentRoute == screen.route,
                onClick = {
                    navController.navigate(screen.route) {
                        popUpTo = navController.graph.startDestination
                        launchSingleTop = true
                    }
                }
            )
        }
    }
}

Back的处理:

setContent {
    NavigationDrawerTheme {
        CompositionLocalProvider(LocalBackPressedDispatcher provides this.onBackPressedDispatcher) {
            AppScaffold()
        }
    }
}