136 lines
3.1 KiB
JavaScript
136 lines
3.1 KiB
JavaScript
/** @namespace H5P */
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var H5P = H5P || {};
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H5P.EventDispatcher = (function () {
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/**
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* The base of the event system.
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* Inherit this class if you want your H5P to dispatch events.
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* @class
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*/
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function EventDispatcher() {
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var self = this;
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/**
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* Keep track of events and listeners for each event.
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* @private
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* @type {Object}
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*/
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var events = {};
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/**
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* Add new event listener.
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*
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* @public
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* @throws {TypeError} listener must be a function
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* @param {String} type Event type
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* @param {Function} listener Event listener
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*/
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self.on = function (type, listener) {
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if (!(listener instanceof Function)) {
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throw TypeError('listener must be a function');
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}
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// Trigger event before adding to avoid recursion
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self.trigger('newListener', type, listener);
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if (!events[type]) {
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// First
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events[type] = [listener];
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}
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else {
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// Append
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events[type].push(listener);
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}
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};
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/**
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* Add new event listener that will be fired only once.
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*
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* @public
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* @throws {TypeError} listener must be a function
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* @param {String} type Event type
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* @param {Function} listener Event listener
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*/
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self.once = function (type, listener) {
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if (!(listener instanceof Function)) {
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throw TypeError('listener must be a function');
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}
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var once = function () {
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self.off(type, once);
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listener.apply(self, arguments);
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};
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self.on(type, once);
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};
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/**
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* Remove event listener.
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* If no listener is specified, all listeners will be removed.
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*
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* @public
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* @throws {TypeError} listener must be a function
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* @param {String} type Event type
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* @param {Function} [listener] Event listener
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*/
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self.off = function (type, listener) {
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if (listener !== undefined && !(listener instanceof Function)) {
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throw TypeError('listener must be a function');
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}
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if (events[type] === undefined) {
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return;
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}
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if (listener === undefined) {
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// Remove all listeners
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delete events[type];
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self.trigger('removeListener', type);
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return;
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}
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// Find specific listener
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for (var i = 0; i < events[type].length; i++) {
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if (events[type][i] === listener) {
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events[type].unshift(i, 1);
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self.trigger('removeListener', type, listener);
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break;
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}
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}
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// Clean up empty arrays
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if (!events[type].length) {
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delete events[type];
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}
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};
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/**
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* Dispatch event.
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*
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* @public
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* @param {String} type Event type
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* @param {...*} args
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*/
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self.trigger = function (type, args) {
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if (events[type] === undefined) {
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return;
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}
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// Copy all arguments except the first
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args = [];
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var i;
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for (i = 1; i < arguments.length; i++) {
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args.push(arguments[i]);
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}
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// Call all listeners
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for (i = 0; i < events[type].length; i++) {
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events[type][i].apply(self, args);
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}
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};
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}
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return EventDispatcher;
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})();
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