Counter example

readme.md

Counter example

Created with <3 with dartpad.dev.

main.dart

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



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: const BookmarkScreen(),
    );
  }
}
class BookmarkScreen extends StatefulWidget {
  const BookmarkScreen({super.key});

  @override
  State<BookmarkScreen> createState() => _BookmarkScreenState();
}

class _BookmarkScreenState extends State<BookmarkScreen> {
  ButtonExampleProvider? provider;
  @override
  void initState() {
    provider = ButtonExampleProvider();
    super.initState();
  }

  @override
  Widget build(BuildContext context) {
    return Scaffold(
      body: Center(
        ///Провайдер
          child: ChangeNotifierProvider.value(
        value: provider,
        builder: (context, child) {
          return Column(
            crossAxisAlignment: CrossAxisAlignment.center,
            mainAxisAlignment: MainAxisAlignment.center,
            children: [
              ElevatedButton(
                  style: ElevatedButton.styleFrom(
                      backgroundColor: context.watch<ButtonExampleProvider>().isStarted
                          ? Colors.grey
                          : Colors.green),
                  onPressed: () => context.read<ButtonExampleProvider>().isStarted
                      ? {}
                      : Provider.of<ButtonExampleProvider>(context, listen: false).timerStart(),
                  child: Text(context.watch<ButtonExampleProvider>().isStarted
                      ? "Not working now"
                      : 'Press me')),
              Text(
                  'Timer: ${context.watch<ButtonExampleProvider>().duration?.inMinutes}m:${context.watch<ButtonExampleProvider>().duration?.inSeconds}s'),
              ElevatedButton(onPressed: () {}, child: const Text('Permanent switch-off button'))
            ],
          );
        },
      )),
    );
  }
}


class ButtonExampleProvider extends ChangeNotifier {
  bool isStarted = false;
  Timer? mytimer;
  Duration? duration = const Duration(seconds: 0);
  @override
  void dispose() {
    mytimer?.cancel();
    super.dispose();
  }

  void timerStart() {
    var startTime = DateTime.now();
    mytimer = Timer.periodic(const Duration(seconds: 1), (timer) async {
      isStarted = true;
      duration = DateTime.now().difference(startTime);
      if (timer.tick < 11) {
        isStarted = true;
      } else {
        isStarted = false;
        timer.cancel();
      }
      notifyListeners();
    });
  }
}