Proyectos de Subversion Moodle

// This file is part of Moodle - http://moodle.org/ //

// Moodle 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, either version 3 of the License, or

// (at your option) any later version.

//

// Moodle 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 Moodle.  If not, see <http://www.gnu.org/licenses/>.

/**

 * Mathjax JS Loader.

 *

 * @module filter_mathjaxloader/loader

 * @copyright 2014 Damyon Wiese  <damyon@moodle.com>

 * @license http://www.gnu.org/copyleft/gpl.html GNU GPL v3 or later

 */

import {

    eventTypes,

    notifyFilterContentRenderingComplete,

} from 'core_filters/events';

/**

 * The users current language - this can't be set until MathJax is loaded - so we need to store it.

 * @property {string} lang

 * @default ''

 * @private

 */

let lang = '';

/**

 * Used to prevent configuring MathJax twice.

 * @property {boolean} configured

 * @default false

 * @private

 */

let configured = false;

/**

 * Called by the filter when it is active on any page.

 * This does not load MathJAX yet - it addes the configuration to the head incase it gets loaded later.

 * It also subscribes to the filter-content-updated event so MathJax can respond to content loaded by Ajax.

 *

 * @param {Object} params List of configuration params containing mathjaxconfig (text) and lang

 */

export const configure = (params) => {

    // Add a js configuration object to the head.

    // See "https://docs.mathjax.org/en/v2.7-latest/advanced/dynamic.html"

    const script = document.createElement("script");

    script.type = "text/x-mathjax-config";

    script[(window.opera ? "innerHTML" : "text")] = params.mathjaxconfig;

    document.getElementsByTagName("head")[0].appendChild(script);

    // Save the lang config until MathJax is actually loaded.

    lang = params.lang;

    // Listen for events triggered when new text is added to a page that needs

    // processing by a filter.

    document.addEventListener(eventTypes.filterContentUpdated, contentUpdated);

};

/**

 * Set the correct language for the MathJax menus. Only do this once.

 *

 * @private

 */

const setLocale = () => {

    if (!configured) {

        if (typeof window.MathJax !== "undefined") {

            window.MathJax.Hub.Queue(function() {

                window.MathJax.Localization.setLocale(lang);

            });

            window.MathJax.Hub.Configured();

            configured = true;

        }

    }

};

/**

 * Add the node to the typeset queue.

 *

 * @param {HTMLElement} node The Node to be processed by MathJax

 * @private

 */

const typesetNode = (node) => {

    if (!(node instanceof HTMLElement)) {

        // We may have been passed a #text node.

        // These cannot be formatted.

        return;

    }

    // MathJax 2.X does not notify when complete. The best we can do, according to their docs, is to queue a callback.

    // See https://docs.mathjax.org/en/v2.7-latest/advanced/typeset.html

    // Note that the MathJax.Hub.Queue() method will return immediately, regardless of whether the typesetting has taken place

    // or not, so you can not assume that the mathematics is visible after you make this call.

    // That means that things like the size of the container for the mathematics may not yet reflect the size of the

    // typeset mathematics. If you need to perform actions that depend on the mathematics being typeset, you should push those

    // actions onto the MathJax.Hub.queue as well.

    window.MathJax.Hub.Queue(["Typeset", window.MathJax.Hub, node]);

    window.MathJax.Hub.Queue([(node) => {

        // The notifyFilterContentRenderingComplete event takes an Array of NodeElements or a NodeList.

        // We cannot create a NodeList so we use an HTMLElement[].

        notifyFilterContentRenderingComplete([node]);

    }, node]);

};

/**

 * Called by the filter when an equation is found while rendering the page.

 */

export const typeset = () => {

    if (!configured) {

        setLocale();

        const elements = document.getElementsByClassName('filter_mathjaxloader_equation');

        for (const element of elements) {

            if (typeof window.MathJax !== "undefined") {

                typesetNode(element);

            }

        }

    }

};

/**

 * Handle content updated events - typeset the new content.

 *

 * @param {CustomEvent} event - Custom event with "nodes" indicating the root of the updated nodes.

 */

export const contentUpdated = (event) => {

    if (typeof window.MathJax === "undefined") {

        return;

    }

    let listOfElementContainMathJax = [];

    let hasMathJax = false;

    // The list of HTMLElements in an Array.

    event.detail.nodes.forEach((node) => {

        if (!(node instanceof HTMLElement)) {

            // We may have been passed a #text node.

            return;

        }

        const mathjaxElements = node.querySelectorAll('.filter_mathjaxloader_equation');

        if (mathjaxElements.length > 0) {

            hasMathJax = true;

        }

        listOfElementContainMathJax.push(mathjaxElements);

    });

    if (!hasMathJax) {

        return;

    }

    const processDelay = window.MathJax.Hub.processSectionDelay;

    // Set the process section delay to 0 when updating the formula.

    window.MathJax.Hub.processSectionDelay = 0;

    // When content is updated never position to hash, it may cause unexpected document scrolling.

    window.MathJax.Hub.Config({positionToHash: false});

    setLocale();

    listOfElementContainMathJax.forEach((mathjaxElements) => {

        mathjaxElements.forEach((node) => typesetNode(node));

    });

    window.MathJax.Hub.processSectionDelay = processDelay;

};