countdown.dart

// Copyright (c) 2019, the Dart project authors.  Please see the AUTHORS file
// for details. 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';

void main() => runApp(MyApp());

class MyApp extends StatelessWidget {
  @override
  Widget build(BuildContext context) {
    return MaterialApp(
      title: 'Flutter Demo',
      debugShowCheckedModeBanner: false,
      theme: ThemeData(
        primarySwatch: Colors.blue,
      ),
      home: MyHomePage(title: 'Flutter Demo Home Page'),
    );
  }
}

class MyHomePage extends StatefulWidget {
  MyHomePage({Key key, this.title}) : super(key: key);

  final String title;

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

class _MyHomePageState extends State<MyHomePage> {
  @override
  Widget build(BuildContext context) {
    return Scaffold(
      appBar: AppBar(
        title: Text(widget.title),
      ),
      body: Center(
        child: Column(
          mainAxisAlignment: MainAxisAlignment.center,
          children: <Widget>[
            TweenAnimationBuilder<double>(
                duration: Duration(seconds: 10),
                tween: Tween(begin: 100.0, end: 0.0),
                onEnd: () {
                  print('Countdown ended');
                },
                builder: (BuildContext context, double value, Widget child) {
                  return Padding(
                      padding: const EdgeInsets.symmetric(vertical: 5),
                      child: Text('${value.toInt()}',
                          textAlign: TextAlign.center,
                          style: TextStyle(
                              color: Colors.black,
                              fontWeight: FontWeight.bold,
                              fontSize: 40)));
                }),
          ],
        ),
      ),
      floatingActionButton: FloatingActionButton(
        onPressed: () {},
        tooltip: 'Increment',
        child: Icon(Icons.add),
      ),
    );
  }
}