flutter_bloc 0.7.0

Flutter Widgets that make it easy to implement the BLoC (Business Logic Component) design pattern. Built to be used with the bloc state management package.

example/lib/main.dart

import 'dart:async';

import 'package:flutter/material.dart';

import 'package:bloc/bloc.dart';
import 'package:flutter_bloc/flutter_bloc.dart';

class SimpleBlocDelegate extends BlocDelegate {
  @override
  void onTransition(Transition transition) {
    print(transition);
  }

  @override
  void onError(Object error, StackTrace stacktrace) {
    print(error);
  }
}

void main() {
  BlocSupervisor().delegate = SimpleBlocDelegate();
  runApp(App());
}

class App extends StatefulWidget {
  @override
  State<StatefulWidget> createState() => _AppState();
}

class _AppState extends State<App> {
  final CounterBloc _counterBloc = CounterBloc();
  final ThemeBloc _themeBloc = ThemeBloc();

  @override
  Widget build(BuildContext context) {
    return BlocProviderTree(
      blocProviders: [
        BlocProvider<CounterBloc>(bloc: _counterBloc),
        BlocProvider<ThemeBloc>(bloc: _themeBloc)
      ],
      child: BlocBuilder(
        bloc: _themeBloc,
        builder: (_, ThemeData theme) {
          return MaterialApp(
            title: 'Flutter Demo',
            home: CounterPage(),
            theme: theme,
          );
        },
      ),
    );
  }

  @override
  void dispose() {
    _counterBloc.dispose();
    _themeBloc.dispose();
    super.dispose();
  }
}

class CounterPage extends StatelessWidget {
  @override
  Widget build(BuildContext context) {
    final CounterBloc _counterBloc = BlocProvider.of<CounterBloc>(context);
    final ThemeBloc _themeBloc = BlocProvider.of<ThemeBloc>(context);

    return Scaffold(
      appBar: AppBar(title: Text('Counter')),
      body: BlocBuilder<CounterEvent, int>(
        bloc: _counterBloc,
        builder: (BuildContext context, int count) {
          return Center(
            child: Text(
              '$count',
              style: TextStyle(fontSize: 24.0),
            ),
          );
        },
      ),
      floatingActionButton: Column(
        crossAxisAlignment: CrossAxisAlignment.end,
        mainAxisAlignment: MainAxisAlignment.end,
        children: <Widget>[
          Padding(
            padding: EdgeInsets.symmetric(vertical: 5.0),
            child: FloatingActionButton(
              child: Icon(Icons.add),
              onPressed: () {
                _counterBloc.dispatch(CounterEvent.increment);
              },
            ),
          ),
          Padding(
            padding: EdgeInsets.symmetric(vertical: 5.0),
            child: FloatingActionButton(
              child: Icon(Icons.remove),
              onPressed: () {
                _counterBloc.dispatch(CounterEvent.decrement);
              },
            ),
          ),
          Padding(
            padding: EdgeInsets.symmetric(vertical: 5.0),
            child: FloatingActionButton(
              child: Icon(Icons.update),
              onPressed: () {
                _themeBloc.dispatch(ThemeEvent.toggle);
              },
            ),
          ),
        ],
      ),
    );
  }
}

enum CounterEvent { increment, decrement }

class CounterBloc extends Bloc<CounterEvent, int> {
  @override
  int get initialState => 0;

  @override
  Stream<int> mapEventToState(int currentState, CounterEvent event) async* {
    switch (event) {
      case CounterEvent.decrement:
        yield currentState - 1;
        break;
      case CounterEvent.increment:
        yield currentState + 1;
        break;
    }
  }
}

enum ThemeEvent { toggle }

class ThemeBloc extends Bloc<ThemeEvent, ThemeData> {
  @override
  ThemeData get initialState => ThemeData.light();

  @override
  Stream<ThemeData> mapEventToState(
    ThemeData currentState,
    ThemeEvent event,
  ) async* {
    switch (event) {
      case ThemeEvent.toggle:
        yield currentState == ThemeData.dark()
            ? ThemeData.light()
            : ThemeData.dark();
        break;
    }
  }
}