scaffold.kt

import android.os.Bundle
import androidx.activity.ComponentActivity
import androidx.activity.compose.BackHandler
import androidx.activity.compose.setContent
import androidx.compose.foundation.BorderStroke
import androidx.compose.foundation.Image
import androidx.compose.foundation.border
import androidx.compose.foundation.clickable
import androidx.compose.foundation.layout.Box
import androidx.compose.foundation.layout.Column
import androidx.compose.foundation.layout.Spacer
import androidx.compose.foundation.layout.fillMaxHeight
import androidx.compose.foundation.layout.fillMaxSize
import androidx.compose.foundation.layout.padding
import androidx.compose.foundation.layout.size
import androidx.compose.foundation.shape.CircleShape
import androidx.compose.material.BottomNavigation
import androidx.compose.material.BottomNavigationItem
import androidx.compose.material.ButtonDefaults
import androidx.compose.material.ExperimentalMaterialApi
import androidx.compose.material.Icon
import androidx.compose.material.IconButton
import androidx.compose.material.ListItem
import androidx.compose.material.MaterialTheme
import androidx.compose.material.Scaffold
import androidx.compose.material.ScaffoldState
import androidx.compose.material.Text
import androidx.compose.material.TextButton
import androidx.compose.material.TopAppBar
import androidx.compose.material.icons.Icons
import androidx.compose.material.icons.filled.Favorite
import androidx.compose.material.icons.filled.Home
import androidx.compose.material.icons.filled.Menu
import androidx.compose.material.icons.filled.Settings
import androidx.compose.material.rememberScaffoldState
import androidx.compose.runtime.Composable
import androidx.compose.runtime.getValue
import androidx.compose.runtime.mutableStateOf
import androidx.compose.runtime.remember
import androidx.compose.runtime.rememberCoroutineScope
import androidx.compose.runtime.setValue
import androidx.compose.ui.Alignment
import androidx.compose.ui.Modifier
import androidx.compose.ui.draw.clip
import androidx.compose.ui.graphics.Color
import androidx.compose.ui.res.painterResource
import androidx.compose.ui.unit.dp
import kotlinx.coroutines.CoroutineScope
import kotlinx.coroutines.launch

class MainActivity : ComponentActivity() {
    override fun onCreate(savedInstanceState: Bundle?) {
        super.onCreate(savedInstanceState)
        setContent {
            ComposeExampleTheme { // 根据你的项目名来设置
                AppScaffold()
            }
        }
    }
}

@Composable
fun AppScaffold() {

    val scaffoldState = rememberScaffoldState()
    val scope = rememberCoroutineScope()

    var selectedItem by remember { mutableStateOf(0) }
    val items = listOf("主页", "我喜欢的", "设置")

    Scaffold(
        scaffoldState = scaffoldState,
        topBar = {
            TopAppBar(
                navigationIcon = {
                    IconButton(
                        onClick = {
                            scope.launch {
                                scaffoldState.drawerState.open()
                            }
                        }
                    ) {
                        Icon(Icons.Filled.Menu, null)
                    }
                },
                title = {
                    Text("魔卡沙的炼金工坊")
                }
            )
        },
        bottomBar = {
            BottomNavigation {
                BottomNavigation {
                    items.forEachIndexed { index, item ->
                        BottomNavigationItem(
                            icon = {
                                when(index){
                                    0 -> Icon(Icons.Filled.Home, contentDescription = null)
                                    1 -> Icon(Icons.Filled.Favorite, contentDescription = null)
                                    else -> Icon(Icons.Filled.Settings, contentDescription = null)
                                }
                            },
                            label = { Text(item) },
                            selected = selectedItem == index,
                            onClick = { selectedItem = index }
                        )
                    }
                }
            }
        },
        drawerContent = {
            AppDrawerContent(scaffoldState, scope)
        }
    ) {
        // 此处需要编写主界面

        // 这里的例子只调用了一个 AppContent
        // 要和 BottomNavigation 合理搭配，显示不同的界面的话
        // 考虑使用 Jetpack Compose Navigation 来实现会更加合理一些
        // 会在文档的后面介绍 Jetpack Compose Navigation

        // 这里的 AppContent 是个伪界面
        // 如果你要先简单的实现多界面，你可以这样编写
        /*
           when(selectedItem) {
                0 -> { Home() }
                1 -> { Favorite() }
                else -> { Settings() }
           }
         */
        // Home(), Favorite(), Settings() 都是单独的 Composable 函数

        AppContent(item = items[selectedItem])
    }
}

@Composable
fun AppContent(
    item: String
) {
    Box(
        modifier = Modifier.fillMaxSize(),
        contentAlignment = Alignment.Center
    ) {
        Text("当前界面是 $item")
    }
}

@OptIn(ExperimentalMaterialApi::class)
@Composable
fun AppDrawerContent(
    scaffoldState: ScaffoldState,
    scope: CoroutineScope
) {

    Box {
        Image(
            painter = painterResource(id = R.drawable.background),
            contentDescription = null
        )
        Column(
            modifier = Modifier.padding(15.dp)
        ) {
            Image(
                painter = painterResource(id = R.drawable.avatar),
                contentDescription = null,
                modifier = Modifier
                    .clip(CircleShape)
                    .size(65.dp)
                    .border(BorderStroke(1.dp, Color.Gray), CircleShape)
            )
            Spacer(Modifier.padding(vertical = 8.dp))
            Text(
                text = "游客12345",
                style = MaterialTheme.typography.body2
            )
        }
    }

    ListItem(
        icon = {
            Icon(Icons.Filled.Home, null)
        },
        modifier = Modifier
            .clickable {

            }
    ) {
        Text("首页")
    }

    Box(
        modifier = Modifier.fillMaxHeight(),
        contentAlignment= Alignment.BottomStart
    ) {
        TextButton(
            onClick = { /*TODO*/ },
            colors = ButtonDefaults.textButtonColors(contentColor = MaterialTheme.colors.onSurface),
        ) {
            Icon(Icons.Filled.Settings, null)
            Text("设置")
        }
    }

    // 编写逻辑
    // 如果 drawer 已经展开了，那么点击返回键收起而不是直接退出 app

    BackHandler(enabled = scaffoldState.drawerState.isOpen) {
        scope.launch {
            scaffoldState.drawerState.close()
        }
    }
}