Cart quantity feature

main.dart

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

const Color darkBlue = Color.fromARGB(255, 18, 32, 47);

void main() {
  runApp(MyApp());
}

class MyApp extends StatelessWidget {
  @override
  Widget build(BuildContext context) {
    return MaterialApp(
      theme: ThemeData.dark().copyWith(
        scaffoldBackgroundColor: darkBlue,
      ),
      debugShowCheckedModeBanner: false,
      home: Scaffold(
        body: ListView.builder(
          itemCount: 5,
          itemBuilder: (context, index) => ChangeNotifierProvider(
            create: (_) => CartQuantityProvider(),
            child: MyWidget(),
          ),
        ),
      ),
    );
  }
}

class MyWidget extends StatelessWidget {
  @override
  Widget build(BuildContext context) {
    return Consumer<CartQuantityProvider>(
      builder: (context, provider, _) => ListTile(
        leading: IconButton(
          onPressed: provider.decreaseQuantity,
          icon: const Icon(Icons.done),
        ),
        trailing: IconButton(
          onPressed: provider.increaseQuantity,
          icon: const Icon(Icons.add),
        ),
        title: Text(
          '${provider.value}',
          style: Theme.of(context).textTheme.headline6,
        ),
      ),
    );
  }
}

class CartQuantityProvider extends ChangeNotifier {
  int value = 0;

  void increaseQuantity() {
    value += 1;
    notifyListeners();
  }

  void decreaseQuantity() {
    value -= 1;
    notifyListeners();
  }
}