samples/web/gallery/lib/demo/material/snack_bar_demo.dart

// Copyright 2018 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_web/material.dart';
import '../../gallery/demo.dart';

const String _text1 =
    'Snackbars provide lightweight feedback about an operation by '
    'showing a brief message at the bottom of the screen. Snackbars '
    'can contain an action.';

const String _text2 =
    'Snackbars should contain a single line of text directly related '
    'to the operation performed. They cannot contain icons.';

const String _text3 =
    'By default snackbars automatically disappear after a few seconds ';

class SnackBarDemo extends StatefulWidget {
  const SnackBarDemo({Key key}) : super(key: key);

  static const String routeName = '/material/snack-bar';

  @override
  _SnackBarDemoState createState() => _SnackBarDemoState();
}

class _SnackBarDemoState extends State<SnackBarDemo> {
  int _snackBarIndex = 1;

  Widget buildBody(BuildContext context) {
    return SafeArea(
      top: false,
      bottom: false,
      child: ListView(
          padding: const EdgeInsets.all(24.0),
          children: <Widget>[
            const Text(_text1),
            const Text(_text2),
            Center(
              child: Row(children: <Widget>[
                RaisedButton(
                    child: const Text('SHOW A SNACKBAR'),
                    onPressed: () {
                      final int thisSnackBarIndex = _snackBarIndex++;
                      Scaffold.of(context).showSnackBar(SnackBar(
                        content: Text('This is snackbar #$thisSnackBarIndex.'),
                        action: SnackBarAction(
                            label: 'ACTION',
                            onPressed: () {
                              Scaffold.of(context).showSnackBar(SnackBar(
                                  content: Text(
                                      'You pressed snackbar $thisSnackBarIndex\'s action.')));
                            }),
                      ));
                    }),
              ]),
            ),
            const Text(_text3),
          ].map<Widget>((Widget child) {
            return Container(
                margin: const EdgeInsets.symmetric(vertical: 12.0),
                child: child);
          }).toList()),
    );
  }

  @override
  Widget build(BuildContext context) {
    return Scaffold(
        appBar: AppBar(
          title: const Text('Snackbar'),
          actions: <Widget>[
            MaterialDemoDocumentationButton(SnackBarDemo.routeName)
          ],
        ),
        body: Builder(
            // Create an inner BuildContext so that the snackBar onPressed methods
            // can refer to the Scaffold with Scaffold.of().
            builder: buildBody));
  }
}