Event

Events are a messaging mechanism used for object interaction within the engine.

Event monitoring

// The event listener will be triggered every time, you need to 
// manually cancel the registration
xxx.on(type, func, target);

Event cancellation

// Cancel all registered events of this type on the object
xxx.off(type);
// Cancel the event of the specified target of the specified 
// callback on the object
xxx.off(type, func, target);

Event distribution

// Dispatch parameters can be specified when the event 
// is dispatched
xxx.emit(type, ...arg);

Note: due to the performance considerations of the underlying event dispatch, only a maximum of 5 event parameters are supported here. Therefore, it is necessary to pay attention to the number of control parameters when passing parameters.

Event descriptions

System events

System events refer to global events, which are monitored and distributed directly from the browser.

cc.systemEvent.on(type, func, target);

Currently supported system events are: touch events, mouse events, gravity events, and key press events. The global event type can be ontained by using cc.SystemEventType.

The key value list obtained by the KEY event can be used by referring to the API Macro.

UI events

Event processing is done in the node. For components, you can register and listen to events by accessing the node this.node. Monitoring events can be registered using the this.node.on() function as follows:

import { _decorator, Component, Node } from "Cocos3D";
const { ccclass } = _decorator;

@ccclass("example")
export class example extends Component {
    onLoad() {
      this.node.on(Node.EventType.TOUCH_CANCEL, this.callback, this);
    }

    callback(){

    }

    onDestroy(){
      // In general, for data recovery control, we will 
      // specify func, and cancel the event when the component 
      // is destroyed
      this.node.off(Node.EventType.TOUCH_CANCEL);
    }