Bloc Concurrency Demos

style: very good analysis
License: MIT

3 different scenarios demonstrating how to structure blocs to take advantage of concurrent event processing in Bloc 7.2/8.0. Each bloc is implemented twice: the old way using mapEventToState, and the new way using on<Event>().

Video Streaming Demo

Demonstrates a bloc that listens to a stream.

Video streaming demo

Cloud File Storage Demo

Demonstrates a bloc that processes events concurrently.

Cloud file storage demo

Registration Form Demo

Demonstrates how to use custom event transformers.

Registration form demo

Generated by the Very Good CLI πŸ€–

Getting Started πŸš€

To run the desired flavor either use the launch configuration in VSCode/Android Studio or use the following commands:

# Development
$ flutter run --flavor development --target lib/main_development.dart

# Staging
$ flutter run --flavor staging --target lib/main_staging.dart

# Production
$ flutter run --flavor production --target lib/main_production.dart

*Bloc Concurrency Demos works on iOS, Android, and Web.

Running Tests πŸ§ͺ

To run all unit and widget tests use the following command:

$ flutter test --coverage --test-randomize-ordering-seed random

To view the generated coverage report you can use lcov.

# Generate Coverage Report
$ genhtml coverage/ -o coverage/

# Open Coverage Report
$ open coverage/index.html

Working with Translations 🌐

This project relies on flutter_localizations and follows the official internationalization guide for Flutter.

Adding Strings

  1. To add a new localizable string, open the app_en.arb file at lib/l10n/arb/app_en.arb.

    "@@locale": "en",
    "counterAppBarTitle": "Counter",
    "@counterAppBarTitle": {
        "description": "Text shown in the AppBar of the Counter Page"
  1. Then add a new key/value and description

    "@@locale": "en",
    "counterAppBarTitle": "Counter",
    "@counterAppBarTitle": {
        "description": "Text shown in the AppBar of the Counter Page"
    "helloWorld": "Hello World",
    "@helloWorld": {
        "description": "Hello World Text"
  1. Use the new string

import 'package:bloc_concurrency_demos/l10n/l10n.dart';

Widget build(BuildContext context) {
  final l10n = context.l10n;
  return Text(l10n.helloWorld);

Adding Supported Locales

Update the CFBundleLocalizations array in the Info.plist at ios/Runner/Info.plist to include the new locale.




Adding Translations

  1. For each supported locale, add a new ARB file in lib/l10n/arb.

β”œβ”€β”€ l10n
β”‚   β”œβ”€β”€ arb
β”‚   β”‚   β”œβ”€β”€ app_en.arb
β”‚   β”‚   └── app_es.arb
  1. Add the translated strings to each .arb file:


    "@@locale": "en",
    "counterAppBarTitle": "Counter",
    "@counterAppBarTitle": {
        "description": "Text shown in the AppBar of the Counter Page"


    "@@locale": "es",
    "counterAppBarTitle": "Contador",
    "@counterAppBarTitle": {
        "description": "Texto mostrado en la AppBar de la pΓ‘gina del contador"


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