MDL-43856 MathJax: Add a mathjax loader filter.
[moodle.git] / filter / mathjaxloader / filter.php
CommitLineData
7f675315
DW
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
25defined('MOODLE_INTERNAL') || die();
26
27/**
28 * Mathjax filtering
29 */
30class 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 $mathjaxlangcodes = array('br',
40 'cdo',
41 'cs',
42 'da',
43 'de',
44 'en',
45 'eo',
46 'es',
47 'fa',
48 'fi',
49 'fr',
50 'gl',
51 'he',
52 'ia',
53 'it',
54 'ja',
55 'ko',
56 'lb',
57 'mk',
58 'nl',
59 'oc',
60 'pl',
61 'pt',
62 'pt-br',
63 'ru',
64 'sl',
65 'sv',
66 'tr',
67 'uk',
68 'zh-hans');
69 $exceptions = array('cz' => 'cs');
70
71 // First see if this is an exception.
72 if (isset($exceptions[$moodlelangcode])) {
73 $moodlelangcode = $exceptions[$moodlelangcode];
74 }
75
76 // Now look for an exact lang string match.
77 if (in_array($moodlelangcode, $mathjaxlangcodes)) {
78 return $moodlelangcode;
79 }
80
81 // Now try shortening the moodle lang string.
82 $moodlelangcode = preg_replace('/-.*/', '', $moodlelangcode);
83 // Look for a match on the shortened string.
84 if (in_array($moodlelangcode, $mathjaxlangcodes)) {
85 return $moodlelangcode;
86 }
87 // All failed - use english.
88 return 'en';
89 }
90
91 /*
92 * Add the javascript to enable mathjax processing on this page.
93 *
94 * @param moodle_page $page The current page.
95 * @param context $context The current context.
96 */
97 public function lazy_init() {
98 global $CFG, $PAGE;
99 // This only requires execution once per request.
100 static $jsinitialised = false;
101
102 if (empty($jsinitialised)) {
103 if (strpos($CFG->httpswwwroot, 'https:') === 0) {
104 $url = get_config('filter_mathjaxloader', 'httpsurl');
105 } else {
106 $url = get_config('filter_mathjaxloader', 'httpurl');
107 }
108 $lang = $this->map_language_code(current_language());
109 $url = new moodle_url($url, array('delayStartupUntil' => 'configured'));
110
111 $moduleconfig = array(
112 'name' => 'mathjax',
113 'fullpath' => $url
114 );
115
116 $PAGE->requires->js_module($moduleconfig);
117
118 $config = get_config('filter_mathjaxloader', 'mathjaxconfig');
119
120 $params = array('mathjaxconfig' => $config, 'lang' => $lang);
121
122 $PAGE->requires->yui_module('moodle-filter_mathjaxloader-loader', 'M.filter_mathjaxloader.init', array($params));
123
124 $jsinitialised = true;
125 }
126 }
127
128 /*
129 * This function wraps the filtered text in a span, that mathjaxloader is configured to process.
130 *
131 * @param string $text The text to filter.
132 * @param array $options The filter options.
133 */
134 public function filter($text, array $options = array()) {
135 // This replaces <tex> blah </tex> syntax with [tex] blah [/tex] syntax
136 // because MathJax cannot handle html tags as delimiters.
137
138 $text = preg_replace('|<(/?) *tex( [^>]*)?>|u', '[\1tex]', $text);
139 if (strpos($text, '$$') !== false || strpos($text, '\\[') !== false || strpos($text, '[tex]') !== false) {
140 // Only call init if there is at least one equation on the page.
141 $this->lazy_init();
142 return '<span class="filter_mathjaxloader_equation">' . $text . '</span>';
143 }
144 return $text;
145 }
146}