Events

Introduction

Events are a way to communicate between different parts of your application. They are a way to decouple your code and make it more maintainable.

Creating an Event

To create an event, you need to create a class that extends VelvetEvent. This class should have a constructor that takes the data you want to pass to the event.

import 'package:velvet_framework/velvet_framework.dart';

class ExampleEvent extends VelvetEvent {
  ExampleEvent(this.message);

  final String message;
}

Dispatching an Event

To dispatch an event, you need to call use the event top-level function.

import 'package:velvet_framework/velvet_framework.dart';

event(ExampleEvent('Hello, World!'));

Listen for an Event

To listen for an event, you need to call the listen method on the event top-level function.

The listen method returns a StreamSubscription object that you can use to cancel the subscription.

Outside a Widget

import 'package:velvet_framework/velvet_framework.dart';

listen<ExampleEvent>((event) {
  print(event.message);
});

// or

final subscription = listen<ExampleEvent>((event) {
  print(event.message);
});

// to cancel the subscription
subscription.cancel();

In a Widget

When listening for events in a widget, you should cancel the subscription when the widget is disposed.

Velvet provides a hook for listening events, the useEventListener hook.

import 'package:velvet_framework/velvet_framework.dart';

class ExampleWidget extends HookWidget {
  @override
  Widget build(BuildContext context) {
    useEventListener<ExampleEvent>((event) {
      print(event.message);
    });

    return Container();
  }
}

Using the hook it is not necessary to cancel the subscription, it is done automatically when the widget is disposed.

Built-in Events

Velvet provides some built-in events that you can listen to or dispatch.

Event Name	Triggered
EnvReadEvent	Event triggered when the environment is read.
VelvetPluginAfterBoot	Event triggered after the Velvet plugin is booted.
VelvetPluginBeforeBoot	Event triggered before the Velvet plugin is booted.
VelvetPluginBeforeRegister	Event triggered before the Velvet plugin is registered.
VelvetPluginAfterRegister	Event triggered after the Velvet plugin is registered.
VelvetPluginManagerAfterBoot	Event triggered after the Velvet plugin manager is booted.
VelvetPluginManagerBeforeBoot	Event triggered before the Velvet plugin manager is booted.
VelvetPluginManagerBeforeRegister	Event triggered before the Velvet plugin manager is registered.
VelvetPluginManagerAfterRegister	Event triggered after the Velvet plugin manager is registered.
HideLoadingEvent	Event triggered when the loading screen is hidden.
LocaleLoadedFromOs	Event triggered when the locale is loaded from the operating system.
LocaleLoadedFromStore	Event triggered when the locale is loaded from the store.