examples/catalog/lib/basic_app_bar.dart

// Copyright 2017 The Chromium Authors. All rights reserved.
// Use of this source code is governed by a BSD-style license that can be
// found in the LICENSE file.

import 'package:flutter/material.dart';

/// Sample Catalog: Basic AppBar
///
/// An AppBar with a title, actions, and an overflow menu. One of the app's
/// choices can be selected action buttons or the menu.
///
/// Sample classes: [AppBar], [IconButton], [PopupMenuButton], [Scaffold].
///
/// See also:
///
///  * The "Layout-Structure" section of the material design specification:
///    <https://material.io/guidelines/layout/structure.html#structure-app-bar>

class Choice {
  const Choice({ this.title, this.icon });
  final String title;
  final IconData icon;
}

const List<Choice> choices = const <Choice>[
  const Choice(title: 'Car', icon: Icons.directions_car),
  const Choice(title: 'Bicycle', icon: Icons.directions_bike),
  const Choice(title: 'Boat', icon: Icons.directions_boat),
  const Choice(title: 'Bus', icon: Icons.directions_bus),
  const Choice(title: 'Train', icon: Icons.directions_railway),
  const Choice(title: 'Walk', icon: Icons.directions_walk),
];

class ChoiceCard extends StatelessWidget {
  const ChoiceCard({ Key key, this.choice }) : super(key: key);

  final Choice choice;

  @override
  Widget build(BuildContext context) {
    final TextStyle textStyle = Theme.of(context).textTheme.display1;
    return new Card(
      color: Colors.white,
      child: new Center(
        child: new Column(
          mainAxisSize: MainAxisSize.min,
          crossAxisAlignment: CrossAxisAlignment.center,
          children: <Widget>[
            new Icon(choice.icon, size: 128.0, color: textStyle.color),
            new Text(choice.title, style: textStyle),
          ],
        ),
      ),
    );
  }
}

class BasicAppBarSample extends StatefulWidget {
  @override
  _BasicAppBarSampleState createState() => new _BasicAppBarSampleState();
}

class _BasicAppBarSampleState extends State<BasicAppBarSample> {
  Choice _selectedChoice = choices[0];

  void _select(Choice choice) {
    setState(() {
      _selectedChoice = choice;
    });
  }

  @override
  Widget build(BuildContext context) {
    return new Scaffold(
      appBar: new AppBar(
        title: const Text('Basic AppBar'),
        actions: <Widget>[
          new IconButton(
            icon: new Icon(choices[0].icon),
            onPressed: () { _select(choices[0]); },
          ),
          new IconButton(
            icon: new Icon(choices[1].icon),
            onPressed: () { _select(choices[1]); },
          ),
          new PopupMenuButton<Choice>(
            onSelected: _select,
            itemBuilder: (BuildContext context) {
              return choices.skip(2).map((Choice choice) {
                return new PopupMenuItem<Choice>(
                  value: choice,
                  child: new Text(choice.title),
                );
              }).toList();
            },
          ),
        ],
      ),
      body: new Padding(
        padding: const EdgeInsets.all(16.0),
        child: new ChoiceCard(choice: _selectedChoice),
      ),
    );
  }
}

void main() {
  runApp(new MaterialApp(home: new BasicAppBarSample()));
}