@oat-sa/tao-test-runner-qti
Version:
TAO Test Runner QTI implementation
88 lines (82 loc) • 3.34 kB
JavaScript
define(['lodash'], function (_) { 'use strict';
_ = _ && Object.prototype.hasOwnProperty.call(_, 'default') ? _['default'] : _;
/*
* This program is free software; you can redistribute it and/or
* modify it under the terms of the GNU General Public License
* as published by the Free Software Foundation; under version 2
* of the License (non-upgradable).
*
* This program is distributed in the hope that it will be useful,
* but WITHOUT ANY WARRANTY; without even the implied warranty of
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
* GNU General Public License for more details.
*
* You should have received a copy of the GNU General Public License
* along with this program; if not, write to the Free Software
* Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301, USA.
*
* Copyright (c) 2017-2021 Open Assessment Technologies SA
*/
/**
* (Pre)load images.
*
* @author Bertrand Chevrier <bertrand@taotesting.com>
*/
var image = {
/**
* The name of the preloader
* @type {string}
*/
name: 'img',
/**
* Manages the preloading of images
* @returns {assetPreloader}
*/
init() {
//keep references to preloaded images attached
//in order to prevent garbage collection of cached images
const images = {};
return {
/**
* Tells whether an image was preloaded or not
* @param {string} url - the url of the image to preload
* @param {string} sourceUrl - the unresolved URL (used to index)
* @param {string} itemIdentifier - the id of the item the asset belongs to
* @returns {boolean}
*/
loaded(url, sourceUrl, itemIdentifier) {
return !!(images[itemIdentifier] && images[itemIdentifier][sourceUrl]);
},
/**
* Preloads an image, using the in memory Image object
* @param {string} url - the url of the image to preload
* @param {string} sourceUrl - the unresolved URL (used to index)
* @param {string} itemIdentifier - the id of the item the asset belongs to
* @returns {Promise}
*/
load(url, sourceUrl, itemIdentifier) {
images[itemIdentifier] = images[itemIdentifier] || {};
if ('Image' in window && !images[itemIdentifier][sourceUrl]) {
images[itemIdentifier][sourceUrl] = new Image();
images[itemIdentifier][sourceUrl].src = url;
}
return Promise.resolve();
},
/**
* Removes images ref so they can be garbage collected
* @param {string} url - the url of the image to unload
* @param {string} sourceUrl - the unresolved URL (used to index)
* @param {string} itemIdentifier - the id of the item the asset belongs to
* @returns {Promise}
*/
unload(url, sourceUrl, itemIdentifier) {
if (images[itemIdentifier]) {
images[itemIdentifier] = _.omit(images[itemIdentifier], sourceUrl);
}
return Promise.resolve();
}
};
}
};
return image;
});