scope_model_example.dart

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

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

class MyApp extends StatelessWidget {
  @override
  Widget build(BuildContext context) {
    return ScopedModel<CounterModel>(
      model: CounterModel(),
      child: MaterialApp(
        debugShowCheckedModeBanner: false,
        home: HomePage(),
      ),
    );
  }
}

class CounterModel extends Model {
  int _counter = 0;

  int get counter => _counter;

  void increment() {
    // First, increment the counter
    _counter++;
    // Then notify all the listeners.
    notifyListeners();
  }
}

class HomePage extends StatelessWidget {
  @override
  Widget build(BuildContext context) {
    return Scaffold(
      appBar: AppBar(
        title: Text("Scope Model"),
        actions: <Widget>[CartCount()],
      ),
      body: Center(
        child: ScopedModelDescendant<CounterModel>(
          builder: (context, child, model) {
            return Text(model.counter.toString(),
                style: Theme.of(context).textTheme.display1);
          },
        ),
      ),
      floatingActionButton: ScopedModelDescendant<CounterModel>(
        builder: (context, child, model) {
          return FloatingActionButton(
            onPressed: () {
              model.increment();
            },
            child: Icon(Icons.add),
          );
        },
      ),
    );
  }
}

class CartCount extends StatelessWidget {
  @override
  Widget build(BuildContext context) {
    return Center(
      child: Stack(
        fit: StackFit.loose,
        children: <Widget>[
          Align(
              alignment: AlignmentDirectional.center,
              child: Padding(
                padding: const EdgeInsets.only(right: 16.0),
                child: Icon(Icons.shopping_cart),
              )),
          Align(
            alignment: AlignmentDirectional.topEnd,
            child: Padding(
              padding: const EdgeInsets.only(left: 16.0),
              child: CircleAvatar(
                backgroundColor: Colors.red,
                radius: 10.0,
                child: ScopedModelDescendant<CounterModel>(
                    builder: (context, child, model) =>
                        Text(model.counter.toString())),
              ),
            ),
          )
        ],
      ),
    );
  }
}