Flutter之Padding

1 、Padding介绍

Padding用来为子元素添加填充，也就是指定子元素与容器边界的距离，作用基本上与Android中ViewGroup的padding属性差不多

const Padding({
    Key key,
    @required this.padding,
    Widget child,
  }) : assert(padding != null),
       super(key: key, child: child);

EdgeInsets提供了一些方法

• • 
    
• fromLTRB(double left, double top, double right, double bottom)：分别指定四个方向的填充。
• all(do

2 、代码测试

@override
  Widget build(BuildContext context) {
      return MaterialApp(
          title: 'open url',
          home: Scaffold(
            appBar: AppBar(
              // Here we take the value from the MyHomePage object that was created by
              // the App.build method, and use it to set our appbar title.
              title: Text('hello flutter'),
            ),
            body: Padding(
//              padding: EdgeInsets.all(16),
//            padding: EdgeInsets.fromLTRB(10, 20, 30, 40),
//            padding: EdgeInsets.only(left: 10, right: 30),
            padding: EdgeInsets.symmetric(vertical: 20),
              child: Container(
                 color: Colors.blue,
              ),
            ),
          ),
      );
  }
}

3、运行效果

分别用上面注释的4个padding效果如下