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Observable.js
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Observable.js
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/**
* @module ol/Observable
*/
import EventTarget from './events/Target.js';
import EventType from './events/EventType.js';
import {listen, listenOnce, unlistenByKey} from './events.js';
/***
* @template {string} Type
* @template {Event|import("./events/Event.js").default} EventClass
* @template Return
* @typedef {(type: Type, listener: (event: EventClass) => ?) => Return} OnSignature
*/
/***
* @template {string} Type
* @template Return
* @typedef {(type: Type[], listener: (event: Event|import("./events/Event").default) => ?) => Return extends void ? void : Return[]} CombinedOnSignature
*/
/**
* @typedef {'change'|'error'} EventTypes
*/
/***
* @template Return
* @typedef {OnSignature<EventTypes, import("./events/Event.js").default, Return> & CombinedOnSignature<EventTypes, Return>} ObservableOnSignature
*/
/**
* @classdesc
* Abstract base class; normally only used for creating subclasses and not
* instantiated in apps.
* An event target providing convenient methods for listener registration
* and unregistration. A generic `change` event is always available through
* {@link module:ol/Observable~Observable#changed}.
*
* @fires import("./events/Event.js").default
* @api
*/
class Observable extends EventTarget {
constructor() {
super();
this.on =
/** @type {ObservableOnSignature<import("./events").EventsKey>} */ (
this.onInternal
);
this.once =
/** @type {ObservableOnSignature<import("./events").EventsKey>} */ (
this.onceInternal
);
this.un = /** @type {ObservableOnSignature<void>} */ (this.unInternal);
/**
* @private
* @type {number}
*/
this.revision_ = 0;
}
/**
* Increases the revision counter and dispatches a 'change' event.
* @api
*/
changed() {
++this.revision_;
this.dispatchEvent(EventType.CHANGE);
}
/**
* Get the version number for this object. Each time the object is modified,
* its version number will be incremented.
* @return {number} Revision.
* @api
*/
getRevision() {
return this.revision_;
}
/**
* @param {string|Array<string>} type Type.
* @param {function((Event|import("./events/Event").default)): ?} listener Listener.
* @return {import("./events.js").EventsKey|Array<import("./events.js").EventsKey>} Event key.
* @protected
*/
onInternal(type, listener) {
if (Array.isArray(type)) {
const len = type.length;
const keys = new Array(len);
for (let i = 0; i < len; ++i) {
keys[i] = listen(this, type[i], listener);
}
return keys;
}
return listen(this, /** @type {string} */ (type), listener);
}
/**
* @param {string|Array<string>} type Type.
* @param {function((Event|import("./events/Event").default)): ?} listener Listener.
* @return {import("./events.js").EventsKey|Array<import("./events.js").EventsKey>} Event key.
* @protected
*/
onceInternal(type, listener) {
let key;
if (Array.isArray(type)) {
const len = type.length;
key = new Array(len);
for (let i = 0; i < len; ++i) {
key[i] = listenOnce(this, type[i], listener);
}
} else {
key = listenOnce(this, /** @type {string} */ (type), listener);
}
/** @type {Object} */ (listener).ol_key = key;
return key;
}
/**
* Unlisten for a certain type of event.
* @param {string|Array<string>} type Type.
* @param {function((Event|import("./events/Event").default)): ?} listener Listener.
* @protected
*/
unInternal(type, listener) {
const key = /** @type {Object} */ (listener).ol_key;
if (key) {
unByKey(key);
} else if (Array.isArray(type)) {
for (let i = 0, ii = type.length; i < ii; ++i) {
this.removeEventListener(type[i], listener);
}
} else {
this.removeEventListener(type, listener);
}
}
}
/**
* Listen for a certain type of event.
* @function
* @param {string|Array<string>} type The event type or array of event types.
* @param {function((Event|import("./events/Event").default)): ?} listener The listener function.
* @return {import("./events.js").EventsKey|Array<import("./events.js").EventsKey>} Unique key for the listener. If
* called with an array of event types as the first argument, the return
* will be an array of keys.
* @api
*/
Observable.prototype.on;
/**
* Listen once for a certain type of event.
* @function
* @param {string|Array<string>} type The event type or array of event types.
* @param {function((Event|import("./events/Event").default)): ?} listener The listener function.
* @return {import("./events.js").EventsKey|Array<import("./events.js").EventsKey>} Unique key for the listener. If
* called with an array of event types as the first argument, the return
* will be an array of keys.
* @api
*/
Observable.prototype.once;
/**
* Unlisten for a certain type of event.
* @function
* @param {string|Array<string>} type The event type or array of event types.
* @param {function((Event|import("./events/Event").default)): ?} listener The listener function.
* @api
*/
Observable.prototype.un;
/**
* Removes an event listener using the key returned by `on()` or `once()`.
* @param {import("./events.js").EventsKey|Array<import("./events.js").EventsKey>} key The key returned by `on()`
* or `once()` (or an array of keys).
* @api
*/
export function unByKey(key) {
if (Array.isArray(key)) {
for (let i = 0, ii = key.length; i < ii; ++i) {
unlistenByKey(key[i]);
}
} else {
unlistenByKey(/** @type {import("./events.js").EventsKey} */ (key));
}
}
export default Observable;