Flutter Control is complex library to maintain App and State management

September 6, 2021 Flutter App, library, Library, State Management

Flutter Control is complex library to maintain App and State management.
Library merges multiple functionality under one hood. This approach helps to tidily bound separated logic into complex solution.

import 'package:flutter_control/core.dart';

App State Management – Managing application state, localization, theme and other global App changes.
Widget State Management – UI / Logic separation. Controlling State and UI updates.
Dependency Injection – Factory, Singleton, Lazy initialization and Service Locator.
Navigation and Routing – Routes, transitions and passing arguments to other pages and Models.
Localization – Json based localization with basic formatting.
Event System – Global event/data stream to easily notify app events.

Flutter Control Core

Control Main static class. Initializes ControlFactory and provides easy access to most of core [Control] objects like BaseLocalization, RouteStore, ControlBroadcast, etc..
ControlFactory Initializes and can store Controls, Models and other Objects. Works as Service Locator and Storage.
Factory has own Storage. Objects in this storage are accessible via custom key or Type. Best practice is to use Type as a key.
Factory is one and only Singleton in this Library.
Core objects of Flutter Control are stored in Factory’s Storage by default (Control.initControl) and are accessible by their Type or via Providers.

    Control.initControl(
      localization: LocalizationConfig(
        defaultLocale: 'en',
        locales: LocalizationAsset.map(locales: ['en_US', 'es_ES']),
      ),
      entries: {
        CounterListControl: CounterListControl(),
      },
      initializers: {
        CounterModel: (_) => CounterModel(),
        CounterDetailControl: (args) => CounterDetailControl(model: Parse.getArg<CounterModel>(args)),
      },
      routes: [
        ControlRoute.build<DetailPage>(builder: (_) => DetailPage()),
      ],
      initAsync: () async {
        loadPreAppConfig();
      },
    );

ControlRoot Wraps basic app flow and initializes [Control]. It’s just shortcut to start with Flutter Control. Via ControlScope is possible to maintain State of this root widget and control whole app state (localization, theme, etc.).
Additionally offers App State management – home screen, localization and theme changes.

    ControlRoot(
      localization: LocalizationConfig(locales: [...]),
      theme: ThemeConfig<MyThemne>(
        builder: (context) => MyTheme(context),
        themes: {...},
      ),
      entries: {...},
      initializers: {...},
      routes: [...],
      states: [
        AppState.init.build(builder: (_) => LoadingPage()),
        AppState.main.build(
          builder: (_) => DashboardPage(),
          transition: TransitionToDashboard(),
        ),
      ],
      app: (setup, home) => MaterialApp(
        key: setup.key,
        title: setup.title('app_name', 'Example App'),
        theme: setup.theme,
        home: home,
        locale: setup.locale,
        supportedLocales: setup.supportedLocales,
        localizationsDelegates: [
          ...
        ],        
      ),
    );

ControlWidget is base abstract class (StatefulWidget) to maintain larger UI parts of App (Pages or complex Widgets). Widget is created with default ControlState to correctly reflect lifecycle of Widget to Models. So there is no need to create custom [State].
Widget will init all containing Models and pass arguments to them.
ControlWidget is immutable so all logic parts (even UI logic and animations) must be controlled from outside. This helps truly separate all code from pure UI (also helps to reuse this code).
SingleControlWidget is focused to single ControlModel. But still can handle multiple Controls.
ControllableWidget – Subscribes to one or more Observable – [ObservableComponent], [ActionControl], [FieldControl], [Stream], [Future], [Notifier]
Whenever state of [ControlObservable] is changed, this Widget is rebuild.These Widgets comes with few mixin classes:
- RouteControl to abstract navigation and easily pass arguments to Routes and init other Pages.
- TickerControl and SingleTickerControl to create [State] with Ticker and provide access to vsync.
- LocalizationProvider, ThemeProvider, OnLayout, ControlsComponent and more..
ControlModel is base class to maintain Business Logic parts.
BaseControl is extended version of [ControlModel] with more functionality. Mainly used for Pages or complex Widgets and also to separate robust Logic parts.
BaseModel is extended but lightweight version of [ControlModel]. Mainly used to control smaller Widgets like Items in dynamic List or to separate/reuse Logic parts.
This Controls comes with few mixin classes to extend base functionality:
- ObservableComponent to control State and notify Widget about changes.
- TickerComponent passes Ticker to Model and enables to control animations outside of Widget.

ControlObservable and ControlSubscription are core underlying observable system and abstract base for other concrete robust implementations – mainly [ActionControl] and [FieldControl].
With ControlBuilder and ControlBuilderGroup on the Widget side. These universal builder widgets can handle all possible types of Notifiers.
ActionControl is one type of Observable used in this Library. It’s quite lightweight and is used to notify Widgets and to provide events about value changes.
Has two variants – Single (just one listener), Broadcast (multiple listeners).
On the Widget side is ControlBuilder to dynamically build Widgets. It’s also possible to use ControlBuilderGroup to group values of multiple Observables.
Upon dismiss of [ActionControl], every ControlSubscription is closed.

    final counter = ActionControl.broadcast<int>(0);

    ActionBuilder<int>(
      control: counter,
      builder: (context, value) => Text(value.toString()),
    );

FieldControl is more robust Observable solution around Stream and StreamController. Primarily is used to notify Widgets and to provide events about value changes.
Can listen Stream, Future or subscribe to another [FieldControl] with possibility to filter and convert values.
[FieldControl] comes with pre-build primitive variants as StringControl, DoubleControl, etc., where is possible to use validation, regex or value clamping. And also ListControl to work with Iterables.
On the Widget side is FieldBuilder to dynamically build Widgets. Also ControlBuilderGroup for use with multiple Observables. It’s also possible to use standard StreamBuilder.
FieldSink or FieldSinkConverter provides Sink of [FieldControl].
Upon dismiss of [FieldControl], every FieldSubscription is closed.

    final counter = FieldControl<int>(0);

    FieldBuilder<int>(
      control: counter,
      builder: (context, value) => Text(value.toString()),
    );

Check Counter Example and TODO List Example at Git repository.

Structure below shows how data and events flows between UI and Controls. ControlWidget can use multiple ControlModels with multiple Models, Streams and Observables..

Localization

BaseLocalization Json based localization, that supports simple strings, plurals and dynamic structures.
Easy access via LocalizationProvider mixin. Localization object is stored in [ControlFactory], so is accessible without context and can be used even in Models, Entities, etc. via Control.localization()
Localization is initialized and loaded in Control by default.
And by default ControlWidget uses this localization via mixin.

    Control.initControl(
      localization: LocalizationConfig(
        defaultLocale: 'en',
        locales: LocalizationAsset.map(locales: ['en_US', 'es_ES']),
      ),
    );

    ControlRoot(
      localization: LocalizationConfig(
        locales: {
          'en': 'assets/localization/en.json',
          'es': 'assets/localization/es.json',
        },
      ),
    );

Check Localization Example and Localization Delegate Example at Git repository.

Global Event System

ControlBroadcast Event stream across whole App. Default broadcaster is part of ControlFactory and is stored there.
Every subscription is bound to it’s key and Type so notification to Listeners arrives only for expected data.
With BroadcastProvider is possible to subscribe to any stream and send data or events from one end of App to the another, even to Widgets and their States. Also custom broadcaster can be created to separate events from global/default stream.

  BroadcastProvider.subscribe<int>('on_count_changed', (value) => updateCount(value));
  BraodcastProvider.broadcast('on_count_changed', 10);

Navigation and Routing

ControlRoute Specifies Route with Transition and [WidgetBuilder] settings for RouteHandler. Handler then solves navigation and passes args to Widgets and Models.
Use RouteControl mixin to enable this navigation with [ControlWidget] and RouteControlProvider mixin with [ControlModel]. Routes can be stored in RouteStore and Route builder is accessible statically via ControlRoute.of.

    Control.initControl(
      routes: [
        ControlRoute.build<DetailPage>(builder: (_) => DetailPage()),
        ControlRoute.build(key: 'detail_super', builder: (_) => DetailPage()).path('super').viaTransition(_transitionBuilder),
      ],
    );

    class ListPage extends ControlWidget with RouteControl {
      Widget build(BuildContext context){
        ...
        routeOf<DetailPage>().openRoute();
        routeOf<DetailPage>().viaTransition(_transitionBuilder).openRoute();
        routeOf(key: 'detail_super').openRoute();
      };
    }

Check Navigation Example and Navigation Stack Example at Git repository.

Other classes

ControlTheme and ThemeProvider Wraps [ThemeData], [MediaQuery] and asset path helper.
InputField Wrapper of [TextField] to provide more functionality and control via InputControl.
DisposeHandler – mixin for any class, helps with object disposing.
PrefsProvider – mixin for any class, helps to store user preferences – based on shared_preferences.
Parse Helps to parse json primitives and Iterables. Also helps to look up Lists and Maps for objects.
FutureBlock Retriggerable delay.
DelayBlock Delay to wrap a block of code to prevent ‘super fast’ completion and UI jiggles.
WidgetInitializer Helps to initialize Widgets with init data.
UnitId Unique Id generator based on Time, Index or just Random.
and more..