134 lines
3.4 KiB
JavaScript
134 lines
3.4 KiB
JavaScript
goog.provide('ol.Observable');
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goog.require('goog.events');
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goog.require('goog.events.EventTarget');
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goog.require('goog.events.EventType');
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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 ol.Observable#changed}.
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*
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* @constructor
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* @extends {goog.events.EventTarget}
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* @fires change
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* @struct
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* @api stable
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*/
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ol.Observable = function() {
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goog.base(this);
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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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goog.inherits(ol.Observable, goog.events.EventTarget);
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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 {goog.events.Key} key The key returned by `on()` or `once()`.
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* @api stable
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*/
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ol.Observable.unByKey = function(key) {
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goog.events.unlistenByKey(key);
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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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ol.Observable.prototype.changed = function() {
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++this.revision_;
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this.dispatchEvent(goog.events.EventType.CHANGE);
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};
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/**
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* Triggered when the revision counter is increased.
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* @event change
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* @api
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*/
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/**
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* Dispatches an event and calls all listeners listening for events
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* of this type. The event parameter can either be a string or an
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* Object with a `type` property.
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*
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* @param {goog.events.EventLike} event Event object.
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* @function
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* @api
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*/
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ol.Observable.prototype.dispatchEvent;
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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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ol.Observable.prototype.getRevision = function() {
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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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* @param {Object=} opt_this The object to use as `this` in `listener`.
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* @return {goog.events.Key} Unique key for the listener.
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* @api stable
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*/
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ol.Observable.prototype.on = function(type, listener, opt_this) {
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return goog.events.listen(this, type, listener, false, opt_this);
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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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* @param {Object=} opt_this The object to use as `this` in `listener`.
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* @return {goog.events.Key} Unique key for the listener.
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* @api stable
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*/
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ol.Observable.prototype.once = function(type, listener, opt_this) {
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return goog.events.listenOnce(this, type, listener, false, opt_this);
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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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* @param {Object=} opt_this The object which was used as `this` by the
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* `listener`.
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* @api stable
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*/
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ol.Observable.prototype.un = function(type, listener, opt_this) {
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goog.events.unlisten(this, type, listener, false, opt_this);
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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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* Note that using the {@link ol.Observable.unByKey} static function is to
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* be preferred.
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* @param {goog.events.Key} key The key returned by `on()` or `once()`.
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* @function
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* @api stable
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*/
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ol.Observable.prototype.unByKey = ol.Observable.unByKey;
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