dart - Flutter Row 主轴对齐不起作用

Question

我试图将两个 Material 按钮排成一行，并且它们之间的间距均匀。但 mainAxisAlignment 小部件不起作用。两个按钮都在行的开头相互粘在一起。

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

尝试简化代码，如下所示:

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'),
        ],
      ),
    ),
  ],
),

查看文档以了解有关差异的更多详细信息:https://flutter.io/docs/development/ui/layout/box-constraints#flex