Flutter Expanded 弹性、自适应、充满剩余

参数详解

属性	说明
flex	弹性
child	元素

 代码示例

class MyBody extends StatelessWidget {
  @override
  Widget build(BuildContext context) {
    return Column(
      children: [
        Text('后自适应'),
        Row(
          children: [
            MyImage('https://raw.githubusercontent.com/think-ing/flutter_demo/master/images/a.jpg'),
            Expanded(
              child: MyImage('https://raw.githubusercontent.com/think-ing/flutter_demo/master/images/b.jpg'),
            )
          ]
        ),

        Text('前自适应'),
        Row(
          children: [
            Expanded(
              child: MyImage('https://raw.githubusercontent.com/think-ing/flutter_demo/master/images/b.jpg'),
            ),
            MyImage('https://raw.githubusercontent.com/think-ing/flutter_demo/master/images/a.jpg'),
          ]
        ),
        
        Text('1：2 比例'),
        Row(
          children: [
            Expanded(
              flex: 1,
              child: MyImage('https://raw.githubusercontent.com/think-ing/flutter_demo/master/images/a.jpg'),
            ),
            
            Expanded(
              flex: 2,
              child: MyImage('https://raw.githubusercontent.com/think-ing/flutter_demo/master/images/b.jpg'),
            )
          ]
        ),


        Text('2：1 比例'),
        Row(
          children: [
            Expanded(
              flex: 2,
              child: MyImage('https://raw.githubusercontent.com/think-ing/flutter_demo/master/images/a.jpg'),
            ),
            
            Expanded(
              flex: 1,
              child: MyImage('https://raw.githubusercontent.com/think-ing/flutter_demo/master/images/b.jpg'),
            )
          ]
        ),

        Text('1：2：1 比例'),
        Row(
          children: [
            Expanded(
              flex: 1,
              child: MyImage('https://raw.githubusercontent.com/think-ing/flutter_demo/master/images/a.jpg'),
            ),
            
            Expanded(
              flex: 2,
              child: MyImage('https://raw.githubusercontent.com/think-ing/flutter_demo/master/images/b.jpg'),
            ),
            Expanded(
              flex: 1,
              child: MyImage('https://raw.githubusercontent.com/think-ing/flutter_demo/master/images/c.jpg'),
            )
          ]
        ),


        Text('2:1:2 比例'),
        Row(
          children: [
            Expanded(
              flex: 2,
              child: MyImage('https://raw.githubusercontent.com/think-ing/flutter_demo/master/images/a.jpg'),
            ),
            
            Expanded(
              flex: 1,
              child: MyImage('https://raw.githubusercontent.com/think-ing/flutter_demo/master/images/b.jpg'),
            ),
            Expanded(
              flex: 2,
              child: MyImage('https://raw.githubusercontent.com/think-ing/flutter_demo/master/images/c.jpg'),
            )
          ]
        ),

      ],
    );
  }
}



//定义一个 公共类
class MyImage extends StatelessWidget {
  String imgUrl;
  MyImage(this.imgUrl);
  @override
  Widget build(BuildContext context) {
    return Container(
      height: 100,
      width: 100,
      child: Image.network(this.imgUrl,fit: BoxFit.cover,),
    );
  }
}

 水平布局可以自适应，垂直布局也是一样

class MyBody extends StatelessWidget {
  @override
  Widget build(BuildContext context) {
    return Column(
      children: [
            MyImage('https://raw.githubusercontent.com/think-ing/flutter_demo/master/images/a.jpg'),
            Expanded(
              child: MyImage('https://raw.githubusercontent.com/think-ing/flutter_demo/master/images/b.jpg'),
            )
          ]
    );
  }
}

 效果图

                     水平自适应                                                          垂直自适应