filter/mathjaxloader/filter.php

   1 <?php
   2 // This file is part of Moodle - http://moodle.org/
   3 //
   4 // Moodle is free software: you can redistribute it and/or modify
   5 // it under the terms of the GNU General Public License as published by
   6 // the Free Software Foundation, either version 3 of the License, or
   7 // (at your option) any later version.
   8 //
   9 // Moodle is distributed in the hope that it will be useful,
  10 // but WITHOUT ANY WARRANTY; without even the implied warranty of
  11 // MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  12 // GNU General Public License for more details.
  13 //
  14 // You should have received a copy of the GNU General Public License
  15 // along with Moodle.  If not, see <http://www.gnu.org/licenses/>.
  16
  17 /**
  18  * This filter provides automatic support for MathJax
  19  *
  20  * @package    filter_mathjaxloader
  21  * @copyright  2013 Damyon Wiese (damyon@moodle.com)
  22  * @license    http://www.gnu.org/copyleft/gpl.html GNU GPL v3 or later
  23  */
  24
  25 defined('MOODLE_INTERNAL') || die();
  26
  27 /**
  28  * Mathjax filtering
  29  */
  30 class filter_mathjaxloader extends moodle_text_filter {
  31
  32     /*
  33      * Perform a mapping of the moodle language code to the equivalent for MathJax.
  34      *
  35      * @param string $moodlelangcode - The moodle language code - e.g. en_pirate
  36      * @return string The MathJax language code.
  37      */
  38     public function map_language_code($moodlelangcode) {
  39
  40         // List of language codes found in the MathJax/localization/ directory.
  41         $mathjaxlangcodes = [
  42             'ar', 'ast', 'bcc', 'bg', 'br', 'ca', 'cdo', 'ce', 'cs', 'cy', 'da', 'de', 'diq', 'en', 'eo', 'es', 'fa',
  43             'fi', 'fr', 'gl', 'he', 'ia', 'it', 'ja', 'kn', 'ko', 'lb', 'lki', 'lt', 'mk', 'nl', 'oc', 'pl', 'pt',
  44             'pt-br', 'qqq', 'ru', 'scn', 'sco', 'sk', 'sl', 'sv', 'th', 'tr', 'uk', 'vi', 'zh-hans', 'zh-hant'
  45         ];
  46
  47         // List of explicit mappings and known exceptions (moodle => mathjax).
  48         $explicit = [
  49             'cz' => 'cs',
  50             'pt_br' => 'pt-br',
  51             'zh_tw' => 'zh-hant',
  52             'zh_cn' => 'zh-hans',
  53         ];
  54
  55         // If defined, explicit mapping takes the highest precedence.
  56         if (isset($explicit[$moodlelangcode])) {
  57             return $explicit[$moodlelangcode];
  58         }
  59
  60         // If there is exact match, it will be probably right.
  61         if (in_array($moodlelangcode, $mathjaxlangcodes)) {
  62             return $moodlelangcode;
  63         }
  64
  65         // Finally try to find the best matching mathjax pack.
  66         $parts = explode('_', $moodlelangcode, 2);
  67         if (in_array($parts[0], $mathjaxlangcodes)) {
  68             return $parts[0];
  69         }
  70
  71         // No more guessing, use English.
  72         return 'en';
  73     }
  74
  75     /*
  76      * Add the javascript to enable mathjax processing on this page.
  77      *
  78      * @param moodle_page $page The current page.
  79      * @param context $context The current context.
  80      */
  81     public function setup($page, $context) {
  82         // This only requires execution once per request.
  83         static $jsinitialised = false;
  84
  85         if (empty($jsinitialised)) {
  86             $url = get_config('filter_mathjaxloader', 'httpsurl');
  87             $lang = $this->map_language_code(current_language());
  88             $url = new moodle_url($url, array('delayStartupUntil' => 'configured'));
  89
  90             $moduleconfig = array(
  91                 'name' => 'mathjax',
  92                 'fullpath' => $url
  93             );
  94
  95             $page->requires->js_module($moduleconfig);
  96
  97             $config = get_config('filter_mathjaxloader', 'mathjaxconfig');
  98             $wwwroot = new moodle_url('/');
  99
 100             $config = str_replace('{wwwroot}', $wwwroot->out(true), $config);
 101
 102             $params = array('mathjaxconfig' => $config, 'lang' => $lang);
 103
 104             $page->requires->yui_module('moodle-filter_mathjaxloader-loader', 'M.filter_mathjaxloader.configure', array($params));
 105
 106             $jsinitialised = true;
 107         }
 108     }
 109
 110     /*
 111      * This function wraps the filtered text in a span, that mathjaxloader is configured to process.
 112      *
 113      * @param string $text The text to filter.
 114      * @param array $options The filter options.
 115      */
 116     public function filter($text, array $options = array()) {
 117         global $PAGE;
 118
 119         $legacy = get_config('filter_mathjaxloader', 'texfiltercompatibility');
 120         $extradelimiters = explode(',', get_config('filter_mathjaxloader', 'additionaldelimiters'));
 121         if ($legacy) {
 122             // This replaces any of the tex filter maths delimiters with the default for inline maths in MathJAX "\( blah \)".
 123             // E.g. "<tex.*> blah </tex>".
 124             $text = preg_replace('|<(/?) *tex( [^>]*)?>|u', '[\1tex]', $text);
 125             // E.g. "[tex.*] blah [/tex]".
 126             $text = str_replace('[tex]', '\\(', $text);
 127             $text = str_replace('[/tex]', '\\)', $text);
 128             // E.g. "$$ blah $$".
 129             $text = preg_replace('|\$\$([\S\s]*?)\$\$|u', '\\(\1\\)', $text);
 130             // E.g. "\[ blah \]".
 131             $text = str_replace('\\[', '\\(', $text);
 132             $text = str_replace('\\]', '\\)', $text);
 133         }
 134
 135         $hasinline = strpos($text, '\\(') !== false && strpos($text, '\\)') !== false;
 136         $hasdisplay = (strpos($text, '$$') !== false) ||
 137                       (strpos($text, '\\[') !== false && strpos($text, '\\]') !== false);
 138
 139         $hasextra = false;
 140
 141         foreach ($extradelimiters as $extra) {
 142             if ($extra && strpos($text, $extra) !== false) {
 143                 $hasextra = true;
 144                 break;
 145             }
 146         }
 147         if ($hasinline || $hasdisplay || $hasextra) {
 148             $PAGE->requires->yui_module('moodle-filter_mathjaxloader-loader', 'M.filter_mathjaxloader.typeset');
 149             if ($hasextra) {
 150                 // If custom dilimeters are used, wrap whole text to prevent autolinking.
 151                 $text = '<span class="nolink">' . $text . '</span>';
 152             } else {
 153                 if ($hasinline) {
 154                     // If the default inline TeX delimiters \( \) are present, wrap each pair in nolink.
 155                     $text = preg_replace('/\\\\\\([\S\s]*?\\\\\\)/u',
 156                         '<span class="nolink">\0</span>', $text);
 157                 }
 158                 if ($hasdisplay) {
 159                     // If default display TeX is used, wrap $$ $$ or \[ \] individually.
 160                     $text = preg_replace('/\$\$[\S\s]*?\$\$|\\\\\\[[\S\s]*?\\\\\\]/u',
 161                         '<span class="nolink">\0</span>', $text);
 162                 }
 163             }
 164             return '<span class="filter_mathjaxloader_equation">' . $text . '</span>';
 165         }
 166         return $text;
 167     }
 168 }