dart - flutter 行主轴对齐不起作用

Question

我试图将两个materialbuttons连续放置，并且它们之间要有均匀的间隔。但是mainAxisAlignment小部件不起作用。在行的开头，两个按钮都彼此粘在一起。

Widget _buildSignInButton() {
    return Row(
      children: <Widget>[
        Container(
          child: new Row(
            mainAxisAlignment: MainAxisAlignment.spaceAround,
            children: <Widget>[
              new SignInButton(
                onPressed: () {
                  _googleSignIn();
                },
                imageUrl: 'assets/images/glogo.png',
              ),
              new SignInButton(
                onPressed: () {
                  _fbSignIn();
                },
                imageUrl: 'assets/images/fblogo.png',
              ),
            ],
          ),
        )
      ],
    );
  }

 Widget build(BuildContext context) {
    return Container(
        child: _buildSignInButton()


    );
  }

Answer 1

尝试像这样简化代码:

Row(
  // children: <Widget>[
  //   new Container(
  //     child: new Row(
        mainAxisAlignment: MainAxisAlignment.spaceAround,
        children: <Widget>[
          new Text('123'),
          new Text('456'),
        ],
  //     ),
  //   ),
  // ],
),

或将 Container替换为 Expanded:

Row(
  children: <Widget>[
    new Expanded(
      child: new Row(
        mainAxisAlignment: MainAxisAlignment.spaceAround,
        children: <Widget>[
          new Text('123'),
          new Text('456'),
        ],
      ),
    ),
  ],
),

checkout 文档以获取有关差异的更多详细信息: https://flutter.io/docs/development/ui/layout/box-constraints#flex