Expanded
是Flutter
当中使用非常高的组件之一,可以动态调整child
组件的尺寸,以及动态填充剩余空间,常见的开发中和Row
或者Column
组件组合起来使用。
源码
const Expanded({
Key? key,
int flex = 1,
required Widget child,
}) : super(key: key, flex: flex, fit: FlexFit.tight, child: child);
属性说明
这里针对源码做出相应的属性说明,熟悉控件的属性方便大家的使用:
属性名称 | 属性说明 |
---|---|
child | 子组件 |
flex | 弹性系数,默认是1 |
示例代码
Row(
mainAxisAlignment: MainAxisAlignment.center,
children: <Widget>[
Container(
width: 100,
height: 100,
color: Colors.redAccent,
),
Container(
width: 100,
height: 100,
color: Colors.blueAccent,
),
Expanded(
child: Container(
width: 100,
height: 100,
color: Colors.yellowAccent,
),
)
],
),
效果如下:
image.png
完整的示例代码
以下的代码,可以直接复制到编译器去运行,方便小伙伴查看运行结果或者直接使用:
import 'package:flutter/material.dart';
void main() {
runApp(const MyApp());
}
class MyApp extends StatelessWidget {
const MyApp({Key? key}) : super(key: key);
@override
Widget build(BuildContext context) {
return MaterialApp(
title: 'Flutter Demo',
theme: ThemeData(
primarySwatch: Colors.blue,
),
home: const MyHomePage(title: 'Expanded Demo'),
);
}
}
class MyHomePage extends StatefulWidget {
const MyHomePage({Key? key, required this.title}) : super(key: key);
final String title;
@override
State<MyHomePage> createState() => _MyHomePageState();
}
class _MyHomePageState extends State<MyHomePage> {
@override
Widget build(BuildContext context) {
return Scaffold(
appBar: AppBar(
title: Text(widget.title),
),
body: Row(
mainAxisAlignment: MainAxisAlignment.center,
children: <Widget>[
Container(
width: 100,
height: 100,
color: Colors.redAccent,
),
Container(
width: 100,
height: 100,
color: Colors.blueAccent,
),
Expanded(
child: Container(
width: 100,
height: 100,
color: Colors.yellowAccent,
),
)
],
),
);
}
}
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