richtext2.dart

@override
  Widget build(BuildContext context) {
    return Scaffold(
      appBar: AppBar(
        title: Text('RichText Widget Demo'),
      ),
      body: Center(
        child: ListView(
          padding: const EdgeInsets.all(20.0),
          children: <Widget>[
            RichText(
              textAlign: TextAlign.center,
              text: TextSpan(
                text: 'display size\n',
                style: Theme.of(context).textTheme.display4,
                children: <TextSpan>[
                  TextSpan(
                      text: longtext[0], style: Theme.of(context).textTheme.display3),
                  TextSpan(
                      text: longtext[1], style: Theme.of(context).textTheme.display2),
                  TextSpan(
                      text: longtext[2], style: Theme.of(context).textTheme.display3),
                  TextSpan(
                      text: longtext[3], style: Theme.of(context).textTheme.display1),
                ],
              ),
            ),
          ],
        ),
      ),
    );
  }
}