學習內容
以下是容器類Widgets的部分彙總：
- Padding
- 佈局限制類容器ConstrainedBox和SizedBox
- 裝飾類容器DecoratedBox
- 變換Transform
- Container容器
- Scaffold、底部導航
各個容器簡易實現
// Padding
class NewPadding extends StatelessWidget {
@override
Widget build(BuildContext context) {
return new Scaffold(
appBar: AppBar(title: Text('Padding學習')),
body: new Padding(
// 上下左右各新增16畫素空白
padding: EdgeInsets.all(16.0),
child: Column(
crossAxisAlignment: CrossAxisAlignment.start,
children: <Widget>[
Padding(
// 左邊新增8畫素補白
padding: const EdgeInsets.only(left: 8.0),
child: Text('Hello world'),
),
Padding(
//上下各新增8畫素補白
padding: const EdgeInsets.symmetric(vertical: 8.0),
child: Text("I am Jack"),
),
Padding(
// 分別指定四個方向的補白
padding: const EdgeInsets.fromLTRB(20.0, .0, 20.0, 20.0),
child: Text("Your friend"),
)
],
)),
);
}
}
// 佈局限制類容器 ConstrianedBox、SizeBox
// 預先定義一個redBox，一個紅色背景的盒子
Widget redBox = DecoratedBox(
decoration: BoxDecoration(color: Colors.red),
);
class NewConstrainedBox extends StatelessWidget {
@override
Widget build(BuildContext context) {
return new Scaffold(
appBar: AppBar(title: Text("ConstrianedBox、SizeBox學習")),
body: new Column(
children: <Widget>[
new Text('ConstrainedBox：'),
new ConstrainedBox(
// 最小高度50，寬度儘可能大的紅色容器
constraints:
BoxConstraints(minWidth: double.infinity, minHeight: 50.0),
// 雖然container高度為5但是，容器的最小高度為50，所以最終生效的是50
child: Container(height: 5.0, child: redBox),
),
// SizedBox用於給子Widget指定固定的寬高
new Text('SizedBox：'),
SizedBox(
width: 80.0,
height: 80.0,
child: redBox,
),
new Text('多重限制案例：'),
// 多重限制案例
ConstrainedBox(
// 父
constraints: BoxConstraints(minWidth: 60.0, minHeight: 60.0),
child: ConstrainedBox(
constraints: BoxConstraints(minWidth: 90.0, minHeight: 20.0),
child: redBox,
)),
new Text('調換限制條件：'),
ConstrainedBox(
// 父
constraints: BoxConstraints(minWidth: 90.0, minHeight: 20.0),
child: ConstrainedBox(
constraints: BoxConstraints(minWidth: 60.0, minHeight: 60.0),
child: redBox,
)),
new Text("'去除'多重限制"),
ConstrainedBox(
constraints: BoxConstraints(minWidth: 60, minHeight: 100),
child: UnconstrainedBox(
child: ConstrainedBox(
constraints: BoxConstraints(minWidth: 90, minHeight: 20),
child: redBox,
),
),
),
],
));
}
}
// 裝飾容器DecoratedBox 漂亮警告
class NewDecoratedBox extends StatelessWidget {
@override
Widget build(BuildContext context) {
return new Scaffold(
appBar: AppBar(title: Text('NewDecoratedBox學習')),
body: new DecoratedBox(
decoration: BoxDecoration(
// 背景漸變
gradient: LinearGradient(colors: [Colors.red, Colors.orange[700]]),
// 畫素圓角
borderRadius: BorderRadius.circular(3.0),
boxShadow: [
BoxShadow(
color: Colors.black54,
offset: Offset(2.0, 2.0),
blurRadius: 4.0),
],
),
child: new Padding(
padding: EdgeInsets.symmetric(horizontal: 80.0, vertical: 18.0),
child: Text(
"Login",
style: TextStyle(color: Colors.white),
),
)),
);
}
}
class NewTransformAndContainer extends StatelessWidget {
@override
Widget build(BuildContext context) {
return new Scaffold(
appBar: AppBar(title: Text("Transform學習")),
body: new Column(
children: <Widget>[
Container(
color: Colors.black,
child: new Transform(
alignment: Alignment.topRight,
transform: new Matrix4.skewY(0.3),
child: new Container(
padding: const EdgeInsets.all(8.0),
color: Colors.deepOrange,
child: const Text("Apartment for rent!"),
),
),
),
DecoratedBox(
decoration: BoxDecoration(color: Colors.red),
child: Transform.translate(
offset: Offset(-20.0, -5.0),
child: Text("Hello world"),
)),
DecoratedBox(
decoration: BoxDecoration(color: Colors.red),
child: Transform.rotate(
//旋轉90度
angle: math.pi / 2,
child: Text("Hello world"),
),
),
DecoratedBox(
decoration: BoxDecoration(color: Colors.red),
child: Transform.scale(
scale: 1.5, //放大到1.5倍
child: Text("Hello world"))),
Container(
margin: EdgeInsets.all(20.0), //容器外補白
color: Colors.orange,
child: Text("Hello world!"),
),
Container(
padding: EdgeInsets.all(20.0), //容器內補白
color: Colors.orange,
child: Text("Hello world!"),
),
Padding(
padding: EdgeInsets.all(20.0),
child: DecoratedBox(
decoration: BoxDecoration(color: Colors.orange),
child: Text("Hello world!"),
),
),
DecoratedBox(
decoration: BoxDecoration(color: Colors.orange),
child: Padding(
padding: const EdgeInsets.all(20.0),
child: Text("Hello world!"),
),
),
Container(
margin: EdgeInsets.only(top: 50.0, left: 120.0), //容器外補白
constraints:
BoxConstraints.tightFor(width: 200.0, height: 150.0), //卡片大小
decoration: BoxDecoration(
//背景裝飾
gradient: RadialGradient(
//背景徑向漸變
colors: [Colors.red, Colors.orange],
center: Alignment.topLeft,
radius: .98),
boxShadow: [
//卡片陰影
BoxShadow(
color: Colors.black54,
offset: Offset(2.0, 2.0),
blurRadius: 4.0)
]),
transform: Matrix4.rotationZ(.2), //卡片傾斜變換
alignment: Alignment.center, //卡片內文字居中
child: Text(
//卡片文字
"5.20", style: TextStyle(color: Colors.white, fontSize: 40.0),
),
),
],
));
}
}
// Scaffold、TabBar、底部導航
class ScaffoldRoute extends StatefulWidget {
@override
_ScaffoldRouteState createState() => new _ScaffoldRouteState();
}
class _ScaffoldRouteState extends State<ScaffoldRoute> {
int _selectedIndex = 1;
@override
Widget build(BuildContext context) {
return Scaffold(
appBar: AppBar(
//導航欄
title: Text("App Name"),
// 手動設定leading自定義選單圖示
// leading: Builder(builder: (context){
// return IconButton(icon: Icon(Icons.dashboard), color: Colors.white,
// onPressed: (){
// Scaffold.of(context).openDrawer();
// },
// );
// },),
actions: <Widget>[
//導航欄右側選單
IconButton(icon: Icon(Icons.share), onPressed: () {}),
],
),
// drawer: new MyDrawer(), //抽屜
bottomNavigationBar: BottomNavigationBar(
items: <BottomNavigationBarItem>[
BottomNavigationBarItem(icon: Icon(Icons.home), title: Text('home')),
BottomNavigationBarItem(icon: Icon(Icons.business), title: Text('business')),
BottomNavigationBarItem(icon: Icon(Icons.school), title: Text("school")),
],
currentIndex: _selectedIndex,
fixedColor: Colors.blue,
onTap: _onItemTapped,
),
floatingActionButton: FloatingActionButton(
child: Icon(Icons.ac_unit),
onPressed: _onAdd,
),
);
}
void _onItemTapped(int index) {
setState(() {
_selectedIndex = index;
});
}
void _onAdd() {}
}
複製程式碼以下是一些效果截圖：
Summary
容器類愈加抽象，但是給佈局和各種酷炫實現打下了堅實的基礎和廣闊的想象力，是個誘惑而充滿挑戰的體驗。