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);
Property | Description |
---|---|
type | the event registration string. |
func | the callback for performing event monitoring. |
target | the event receiving object. |
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
.
Event Name | Event Type Description |
---|---|
TOUCH_START | Finger starts touch event. |
TOUCH_MOVE | When your finger moves on the screen. |
TOUCH_END | The finger ends the touch event. |
TOUCH_CANCEL | When the finger leaves the screen outside the target node area. |
MOUSE_DOWN | Triggered once when the mouse is pressed. |
MOUSE_MOVE | When the mouse moves on the target node in the target node area, whether it is pressed or not. |
MOUSE_UP | Triggered once when the mouse is released from the pressed state. |
MOUSE_WHEEL | Mouse scroll event. |
MOUSE_ENTER | When the mouse moves into the target node area, whether it is pressed or not. |
MOUSE_EXIT | When the mouse moves out of the target node area, whether it is pressed or not. |
KEY_DOWN | Event triggered when a key is pressed. |
KEY_UP | Event triggered when the key is released. |
DEVICEMOTION | Gravity sensing. |
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);
}
Event Name | Event Type Description |
---|---|
TRANSFORM_CHANGED | Node change position, rotation or zoom event. |
POSITION_PART | Node position change event. Unified monitoring by TRANSFORM_CHANGED, and judge the type after distribution. |
ROTATION_PART | Node rotation event. Unified monitoring by TRANSFORM_CHANGED, and judge the type after distribution. |
SCALE_PART | Node zoom event. Unified monitoring by TRANSFORM_CHANGED, and judge the type after distribution. |
SIZE_CHANGED | Event triggered when the node size changes. |
ANCHOR_CHANGED | Event triggered when the node anchor changes. |
CHILD_ADDED | Node subclass added. |
CHILD_REMOVED | Node subclasses removed. |