플러터 Flutter 스톱워치 간단 구현 Stopwatch

• 코드 작성

import 'package:flutter/material.dart';
import 'dart:async';

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

class StopwatchApp extends StatelessWidget {
  @override
  Widget build(BuildContext context) {
    return MaterialApp(
      title: 'Stopwatch App',
      theme: ThemeData(primarySwatch: Colors.blue),
      home: StopwatchHomePage(),
    );
  }
}

class StopwatchHomePage extends StatefulWidget {
  @override
  _StopwatchHomePageState createState() => _StopwatchHomePageState();
}

class _StopwatchHomePageState extends State<StopwatchHomePage> {
  Stopwatch _stopwatch = Stopwatch();
  Timer? _timer;
  String _elapsedTime = '00:00:00';

  void _startTimer() {
    _stopwatch.start();
    _timer = Timer.periodic(Duration(milliseconds: 100), (Timer timer) {
      setState(() {
        _elapsedTime = _formatTime(_stopwatch.elapsedMilliseconds);
      });
    });
  }

  void _stopTimer() {
    _stopwatch.stop();
    _timer?.cancel();
  }

  void _resetTimer() {
    _stopwatch.reset();
    setState(() {
      _elapsedTime = '00:00:00';
    });
  }

  String _formatTime(int milliseconds) {
    int seconds = (milliseconds / 1000).truncate();
    int minutes = (seconds / 60).truncate();
    int hours = (minutes / 60).truncate();

    String hoursStr = (hours % 60).toString().padLeft(2, '0');
    String minutesStr = (minutes % 60).toString().padLeft(2, '0');
    String secondsStr = (seconds % 60).toString().padLeft(2, '0');

    return '$hoursStr:$minutesStr:$secondsStr';
  }

  @override
  void dispose() {
    _stopwatch.stop();
    _timer?.cancel();
    super.dispose();
  }

  @override
  Widget build(BuildContext context) {
    return Scaffold(
      appBar: AppBar(title: Text('Stopwatch')),
      body: Center(
        child: Column(
          mainAxisAlignment: MainAxisAlignment.center,
          children: <Widget>[
            Text(
              _elapsedTime,
              style: TextStyle(fontSize: 40),
            ),
            SizedBox(height: 20),
            Row(
              mainAxisAlignment: MainAxisAlignment.center,
              children: <Widget>[
                RaisedButton(
                  onPressed: _startTimer,
                  child: Text('Start'),
                ),
                SizedBox(width: 20),
                RaisedButton(
                  onPressed: _stopTimer,
                  child: Text('Stop'),
                ),
                SizedBox(width: 20),
                RaisedButton(
                  onPressed: _resetTimer,
                  child: Text('Reset'),
                ),
              ],
            ),
          ],
        ),
      ),
    );
  }
}