Flutter 容器FractionallySizedBox

FractionallySizedBox

用法与SizedBox类似，只不过FractionallySizedBox的宽高是百分比大小，widthFactor，heightFactor参数就是相对于父控件的比例。注意设置FractionallySizedBox宽高后，其子组件设置的宽高将不起作用

import 'package:flutter/material.dart';
import 'package:webview/webview.dart';

void main() {
  runApp(MyApp());
}

class MyApp extends StatelessWidget {
  const MyApp({Key key}) : super(key: key);
  @override
  Widget build(BuildContext context) {
    return MaterialApp(
      home: Scaffold(
        body: LayoutDemo(),
      ),
    );
  }
}


class LayoutDemo extends StatelessWidget {
  @override
  Widget build(BuildContext context) {
    return new Scaffold(
      appBar: new AppBar(
        title: new Text('FractionallySizedBox百分比布局示例'),
      ),
      body: new Container(
        color: Colors.blueGrey,
        height: 200.0,
        width: 200.0,
        child: new FractionallySizedBox(
          alignment: Alignment.topLeft,//元素左上角对齐
          widthFactor: 0.5,//宽度因子
          heightFactor: 1.5,//高度因子
          child: new Container(
            color: Colors.green,
          ),
        ),
      ),
    );
  }
}