JetPackCompose底部导航栏的实现方法详解

//导航label数组
private val labels = arrayOf("首页", "房讯", "消息", "我的")
//导航默认图标集合
private val defImages =
    arrayOf(R.mipmap.img_index, R.mipmap.img_info, R.mipmap.img_message, R.mipmap.img_preson)
//导航选中图标集合
private var selectImages =
    arrayOf(
        R.mipmap.img_index_select,
        R.mipmap.img_info_select,
        R.mipmap.img_message_select,
        R.mipmap.img_preson_select
    )
//导航选中索引
private var selectIndex by mutableStateOf(0)

setContent {
    val navController = rememberNavController()
    Scaffold(
        //设置底部导航栏
        bottomBar = {
            BuildBottomBar(labels = labels, navController)
        },
    ) {
        //设置页面主内容区域，这里通过NavHost，根据选中不同的导航栏Tab导航到不同的页面。
        NavHost(navController = navController, startDestination = labels[selectIndex]) {
            composable(labels[0]) {
                //首页Compose
                IndexPage()
            }
            composable(labels[1]) {
                //咨询Compose
                InfoPage()
            }
            composable(labels[2]) {
                //消息Compose
                MessagePage()
            }
            composable(labels[3]) {
                //个人中心Compose
                PersonPage()
            }
        }
    }
}

BottomNavigation(backgroundColor = Color.White, elevation = 6.dp) {
    for (i in labels.indices) {
        BottomNavigationItem(selected = selectIndex == i, onClick = {
            selectIndex = i
            navController.navigate(labels[i])
        }, icon = {
            Image(
                painter = painterResource(id = if (selectIndex == i) selectImages[i] else defImages[i]),
                contentDescription = labels[i],
                modifier = Modifier.size(25.dp)
            )
        }, label = {
            Text(text = labels[i], color = if (selectIndex == i) Color.Red else Color.Gray)
        })
    }
}

val navController = rememberNavController()

navController.navigate(labels[i])