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