Jetpack Compose学习(7)——MD样式架构组件Scaffold及导航底部菜单
Jetpack Compose學習(7)——MD樣式架構組件Scaffold及導航底部菜單 | Stars-One的雜貨小窩
Compose給我們提供了一個Material Design樣式的首頁組件(Scaffold),我們可以直接套用從而完成一個APP的首頁界面
本系列以往文章請查看此分類鏈接Jetpack compose學習
由于Scaffold中還包含有其他的組件,所以講解Scaffold先講解前置的一些組件
TopAppBar
首先,便是TopAppBar,其本質就是我們Android原生常見的Toolbar,不過其封裝的比較好,可以快速構建,下面是其的參數列表
TopAppBar(
title: @Composable () -> Unit,
modifier: Modifier = Modifier,
navigationIcon: @Composable (() -> Unit)? = null,
actions: @Composable RowScope.() -> Unit = {},
backgroundColor: Color = MaterialTheme.colors.primarySurface,
contentColor: Color = contentColorFor(backgroundColor),
elevation: Dp = AppBarDefaults.TopAppBarElevation
)
title 標題,接收Compose組件,可以傳個Text文本進去
modifier 修飾符,詳情見上一章節
navigationIcon 導航圖標
actions 動作組件
backgroundColor 背景色
contentColor 內容顏色
elevation 陰影
可能說的那么明確,我們直接上代碼和效果圖,各位就清晰了
TopAppBar(
navigationIcon = {
IconButton(
onClick = {}
) {
Icon(Icons.Filled.Menu, null)
}
},
title = {
Text("stars-one的測試應用")
},actions = {
IconButton(
onClick = {}
) {
Icon(Icons.Filled.Share, null)
}
IconButton(
onClick = {}
) {
Icon(Icons.Filled.Settings, null)
}
}
)
效果圖如下
FloatingActionButton
比較常見的懸浮按鈕,一般里面是個簡單的按鈕,參數與之前的Button一樣,詳情請參考Jetpack Compose學習(3)——圖標(Icon) 按鈕(Button) 輸入框(TextField) 的使用 | Stars-One的雜貨小窩
FloatingActionButton(
onClick: () -> Unit,
modifier: Modifier = Modifier,
interactionSource: MutableInteractionSource = remember { MutableInteractionSource() },
shape: Shape = MaterialTheme.shapes.small.copy(CornerSize(percent = 50)),
backgroundColor: Color = MaterialTheme.colors.secondary,
contentColor: Color = contentColorFor(backgroundColor),
elevation: FloatingActionButtonElevation = FloatingActionButtonDefaults.elevation(),
content: @Composable () -> Unit
)
使用:
FloatingActionButton(onClick = { /*TODO*/ }) {
Icon(imageVector = Icons.Default.Add, contentDescription = null)
}
PS: 一般這個與
Scaffold連用,Scaffold里面可控制FloatingActionButton的位置
除此之外,還有個ExtendedFloatingActionButton,這種就是可以帶圖標和文字的,如下圖
ExtendedFloatingActionButton(
icon = { Icon(Icons.Filled.Favorite, contentDescription = null) },
text = { Text("ADD TO BASKET") },
onClick = { /*do something*/ }
)
ExtendedFloatingActionButton和FloatingActionButton區別是,ExtendedFloatingActionButton是以文字為主,圖標是可選的,而FloatingActionButton只顯示圖標
BottomAppBar
這個與之前的TopAppBar參數有所不同,從名字看我們知道其實放在底部的一個Toolbar,但是其本身是不帶有位置控制,也是得與Scaffold連用,如果單獨使用,效果也是會和TopAppBar的一樣放在頁面的頂頭
BottomAppBar(
modifier: Modifier = Modifier,
backgroundColor: Color = MaterialTheme.colors.primarySurface,
contentColor: Color = contentColorFor(backgroundColor),
cutoutShape: Shape? = null,
elevation: Dp = AppBarDefaults.BottomAppBarElevation,
contentPadding: PaddingValues = AppBarDefaults.ContentPadding,
content: @Composable RowScope.() -> Unit
)
可以把這個布局看作是個Row布局,里面的參數從名字都能看到出來,設置背景色或者設置padding邊距的,這里不再贅述
唯一值得注意的是cutoutShape屬性,如果在Scaffold中,有BottomAppBar和FloatingActionButton,可以實現下面的效果
BottomNavigation
BottomNavigation里面會有N個BottomNavigationItem,這里就看你自己準備定義多少個菜單項了
BottomNavigation(
modifier: Modifier = Modifier,
backgroundColor: Color = MaterialTheme.colors.primarySurface,
contentColor: Color = contentColorFor(backgroundColor),
elevation: Dp = BottomNavigationDefaults.Elevation,
content: @Composable RowScope.() -> Unit
)
BottomNavigation提供的一些參數也就是改變顏色或者陰影,重點是在BottomNavigationItem
BottomNavigationItem(
selected: Boolean,
onClick: () -> Unit,
icon: @Composable () -> Unit,
modifier: Modifier = Modifier,
enabled: Boolean = true,
label: @Composable (() -> Unit)? = null,
alwaysShowLabel: Boolean = true,
interactionSource: MutableInteractionSource = remember { MutableInteractionSource() },
selectedContentColor: Color = LocalContentColor.current,
unselectedContentColor: Color = selectedContentColor.copy(alpha = ContentAlpha.medium)
)
BottomNavigationItem有個selected參數,表示是否選中
icon則是圖標的設置,label則是文字,這兩個都是需要接收一個組件的
selectedContentColor 選中顏色
unselectedContentColor 未選中顏色
下面直接來個例子講解
var selectIndex by remember {
mutableStateOf(0)
}
val navList = listOf("首頁","發現","我的")
BottomNavigation() {
navList.forEachIndexed { index, str ->
BottomNavigationItem(
selected = index == selectIndex, onClick = { selectIndex = index },
icon = {
Icon(imageVector = Icons.Default.Favorite, contentDescription =null )
},label = {Text(str)}
)
}
}
Text(text = "這是${navList[selectIndex]}")
效果如下所示
Scaffold
Scaffold(
modifier: Modifier = Modifier,
scaffoldState: ScaffoldState = rememberScaffoldState(),
topBar: @Composable () -> Unit = {},
bottomBar: @Composable () -> Unit = {},
snackbarHost: @Composable (SnackbarHostState) -> Unit = { SnackbarHost(it) },
floatingActionButton: @Composable () -> Unit = {},
floatingActionButtonPosition: FabPosition = FabPosition.End,
isFloatingActionButtonDocked: Boolean = false,
drawerContent: @Composable (ColumnScope.() -> Unit)? = null,
drawerGesturesEnabled: Boolean = true,
drawerShape: Shape = MaterialTheme.shapes.large,
drawerElevation: Dp = DrawerDefaults.Elevation,
drawerBackgroundColor: Color = MaterialTheme.colors.surface,
drawerContentColor: Color = contentColorFor(drawerBackgroundColor),
drawerScrimColor: Color = DrawerDefaults.scrimColor,
backgroundColor: Color = MaterialTheme.colors.background,
contentColor: Color = contentColorFor(backgroundColor),
content: @Composable (PaddingValues) -> Unit
)
屬性說明
topBar 頂部的布局
bottomBar 底部的布局
floatingActionButton 懸浮按鈕布局
floatingActionButtonPosition 懸浮按鈕位置,有FabPosition.End(默認)和FabPosition.Center可選
isFloatingActionButtonDocked 與BottomAppBar配合使用,可以實現底部導航條的裁剪效果,效果可以看下圖
drawerGesturesEnabled 是否開啟側邊抽屜手勢(開啟后可側滑彈出抽屜)
drawerShape 抽屜的形狀
drawerContent 側邊抽屜內容,是個Column布局,自己可以順便排列
drawerElevation 側邊抽屜的陰影
drawerBackgroundColor 側邊抽屜的背景色
drawerContentColor 側邊抽屜內容顏色(似乎是覆蓋字體顏色而已)
drawerScrimColor 側邊抽屜遮蓋最底層的顏色
基本使用
使用5個屬性topBar bottomBar floatingActionButton floatingActionButtonPosition isFloatingActionButtonDocked,實現個簡單架構效果
Scaffold(
topBar = {
TopAppBar(
navigationIcon = {
IconButton(
onClick = {}
) {
Icon(Icons.Filled.Menu, null)
}
},
title = {
Text("stars-one的測試應用")
},actions = {
IconButton(
onClick = {}
) {
Icon(Icons.Filled.Share, null)
}
IconButton(
onClick = {}
) {
Icon(Icons.Filled.Settings, null)
}
}
)
},
floatingActionButton = {
FloatingActionButton(onClick = { /*TODO*/ }) {
Icon(imageVector = Icons.Default.Favorite, contentDescription = null)
}
},
bottomBar = {
BottomAppBar(cutoutShape = CircleShape) {
}
},
//注意此參數,可以實現圖中那種被裁剪的效果,前提是上面的cutoutShape也有設置
isFloatingActionButtonDocked = true,
floatingActionButtonPosition = FabPosition.End
) {
//這里是主界面
Text("我是要展示的內容")
}
效果如下圖所示
底部導航條
我們在上面的基礎改下即可(主要是bottomAppBar這個參數),代碼如下所示
//當前選擇的NavItem
var selectIndex by remember { mutableStateOf(0) }
val navTextList = listOf("主頁", "發現", "我的")
//圖標
val iconList = listOf(Icons.Default.Home,Icons.Default.Favorite,Icons.Default.AccountBox)
Scaffold(
topBar = {
TopAppBar(
navigationIcon = {
IconButton(
onClick = {}
) {
Icon(Icons.Filled.Menu, null)
}
},
title = {
Text("stars-one的測試應用")
},actions = {
IconButton(
onClick = {}
) {
Icon(Icons.Filled.Share, null)
}
IconButton(
onClick = {}
) {
Icon(Icons.Filled.Settings, null)
}
}
)
},
floatingActionButton = {
FloatingActionButton(onClick = { /*TODO*/ }) {
Icon(imageVector = Icons.Default.Add, contentDescription = null)
}
},
bottomBar = {
BottomNavigation() {
navTextList.forEachIndexed { index, str ->
BottomNavigationItem(label = {Text(str)},selected = index==selectIndex , onClick = {selectIndex = index },icon = {
Icon(imageVector = iconList[index], contentDescription = null)
})
}
}
},
//注意此參數,可以實現圖中那種被裁剪的效果,前提是上面的cutoutShape也有設置
floatingActionButtonPosition = FabPosition.End
) {
//這里是主界面
//根據底部導航選中的下標改變展示的頁面
when(selectIndex){
0 -> Text("這是首頁")
1 -> Text("這是發現")
2 -> Text("這是我的")
}
}
效果如下圖所示
帶側邊抽屜
這里需要注意的是,彈出側邊抽屜是個掛起操作(suspend),所以需要使用到Kotlin中的協程,不過不是涉及太深,我們先知道怎么用即可,后面有空我再補充協程的用法
這里主要是測試了帶drawer開頭的那幾個參數,及點擊左上角的菜單按鈕彈出側邊抽屜功能(即對應的點擊事件)
//狀態
val scaffoldState = rememberScaffoldState()
//協程的作用域
val scope = rememberCoroutineScope()
//當前選擇的NavItem
var selectIndex by remember { mutableStateOf(0) }
val navTextList = listOf("主頁", "發現", "我的")
//圖標
val iconList =
listOf(Icons.Default.Home, Icons.Default.Favorite, Icons.Default.AccountBox)
Scaffold(
scaffoldState = scaffoldState,
topBar = {
TopAppBar(
navigationIcon = {
IconButton(
onClick = {
//使用協程
scope.launch {
//改變狀態,顯示drawer抽屜
scaffoldState.drawerState.open()
}
}
) {
Icon(Icons.Filled.Menu, null)
}
},
title = {
Text("stars-one的測試應用")
}, actions = {
IconButton(
onClick = {}
) {
Icon(Icons.Filled.Share, null)
}
IconButton(
onClick = {}
) {
Icon(Icons.Filled.Settings, null)
}
}
)
},
floatingActionButton = {
FloatingActionButton(onClick = { /*TODO*/ }) {
Icon(imageVector = Icons.Default.Add, contentDescription = null)
}
},
bottomBar = {
BottomNavigation() {
navTextList.forEachIndexed { index, str ->
BottomNavigationItem(
label = { Text(str) },
selected = index == selectIndex,
onClick = { selectIndex = index },
icon = {
Icon(
imageVector = iconList[index],
contentDescription = null
)
})
}
}
},
//注意此參數,可以實現圖中那種被裁剪的效果,前提是上面的cutoutShape也有設置
floatingActionButtonPosition = FabPosition.End,
drawerContent = {
Text("這是抽屜的內容")
},
drawerContentColor = Color.Black,
drawerBackgroundColor = Color.Green,
drawerGesturesEnabled = true,
drawerScrimColor = Color.Red,
drawerShape = RoundedCornerShape(20.dp)
) {
//這里是主界面
//根據底部導航選中的下標改變展示的頁面
when (selectIndex) {
0 -> Text("這是首頁")
1 -> Text("這是發現")
2 -> Text("這是我的")
}
}
參考
Scaffold - Jetpack Compose
TopAppBar - Jetpack Compose
BottomAppBar官方文檔
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