app_about.dart

import 'package:flutter/material.dart';

/// This Widget is the main application widget.
class AboutDemo extends StatelessWidget {
  @override
  Widget build(BuildContext context) {
    return MaterialApp(
      debugShowCheckedModeBanner: false,
      darkTheme: ThemeData.dark(),
      theme: ThemeData(brightness: Brightness.dark),
      title: 'Flutter About Widgets',
      home: MyStatelessWidget(),
    );
  }
}

class MyStatelessWidget extends StatelessWidget {
  MyStatelessWidget({Key key}) : super(key: key);

  @override
  Widget build(BuildContext context) {
    final List<Widget> aboutBoxChildren = <Widget>[
      SizedBox(
        height: 20,
      ),
      Text('App information'),
      Text('App Privacy Policy'),
      Text('App Terms of Service'),
      RichText(
        text: TextSpan(
          children: <TextSpan>[
            TextSpan(
                style: TextStyle(color: Theme.of(context).accentColor),
                text: 'Site URL'),
          ],
        ),
      )
    ];

    return Scaffold(
      appBar: AppBar(
        title: Text('My Cool App'),
      ),
      drawer: Drawer(
        child: SingleChildScrollView(
          child: SafeArea(
            child: Column(
              children: <Widget>[
                AboutListTile(
                  child: Text('About app'),
                  icon: Icon(
                    Icons.info,
                  ),
                  applicationIcon: Icon(
                    Icons.local_play,
                    size: 65,
                    color: Theme.of(context).accentColor,
                  ),
                  applicationName: 'My Cool App',
                  applicationVersion: '1.0.25',
                  applicationLegalese: '© 2019 Company',
                  aboutBoxChildren: aboutBoxChildren,
                ),
              ],
            ),
          ),
        ),
      ),
      body: Center(
        child: RaisedButton(
          child: Text('Show About Dialog'),
          color: Theme.of(context).accentColor,
          textColor: Colors.black,
          onPressed: () {
            showAboutDialog(
              context: context,
              applicationIcon: Icon(
                Icons.local_play,
                size: 65,
                color: Theme.of(context).accentColor,
              ),
              applicationName: 'My Cool App',
              applicationVersion: '1.0.25',
              applicationLegalese: '© 2019 Company',
              children: aboutBoxChildren,
            );
          },
        ),
      ),
    );
  }
}