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<?php// 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/>./*** Moodle - Filter for converting TeX expressions to cached gif images** This Moodle text filter converts TeX expressions delimited* by either $$...$$ or by <tex...>...</tex> tags to gif images using* mimetex.cgi obtained from http: *www.forkosh.com/mimetex.html authored by* John Forkosh john@forkosh.com. Several binaries of this areincluded with* this distribution.* Note that there may be patent restrictions on the production of gif images* in Canada and some parts of Western Europe and Japan until July 2004.** @package filter* @subpackage tex* @copyright 2004 Zbigniew Fiedorowicz fiedorow@math.ohio-state.edu* Originally based on code provided by Bruno Vernier bruno@vsbeducation.ca* @license http://www.gnu.org/copyleft/gpl.html GNU GPL v3 or later*/defined('MOODLE_INTERNAL') || die;require_once($CFG->libdir . '/classes/useragent.php');/*** Create TeX image link.** @param string $imagefile name of file* @param string $tex TeX notation (html entities already decoded)* @param int $height O means automatic* @param int $width O means automatic* @param string $align* @param string $alt* @return string HTML markup*/function filter_text_image($imagefile, $tex, $height, $width, $align, $alt) {global $CFG, $OUTPUT;if (!$imagefile) {throw new coding_exception('image file argument empty in filter_text_image()');}// Work out any necessary inline style.$rules = array();if ($align !== 'middle') {$rules[] = 'vertical-align:' . $align . ';';}if ($height) {$rules[] = 'height:' . $height . 'px;';}if ($width) {$rules[] = 'width:' . $width . 'px;';}if (!empty($rules)) {$style = ' style="' . implode('', $rules) . '" ';} else {$style = '';}// Prepare the title attribute.// Note that we retain the title tag as TeX format rather than using// the alt text, even if supplied. The alt text is intended for blind// users (to provide a text equivalent to the equation) while the title// is there as a convenience for sighted users who want to see the TeX// code.$title = 'title="'.s($tex).'"';if ($alt === '') {$alt = s($tex);} else {$alt = s(html_entity_decode($tex, ENT_QUOTES, 'UTF-8'));}// Build the output.$anchorcontents = "<img class=\"texrender\" $title alt=\"$alt\" src=\"";if ($CFG->slasharguments) { // Use this method if possible for better caching$anchorcontents .= "$CFG->wwwroot/filter/tex/pix.php/$imagefile";} else {$anchorcontents .= "$CFG->wwwroot/filter/tex/pix.php?file=$imagefile";}$anchorcontents .= "\" $style/>";if (!file_exists("$CFG->dataroot/filter/tex/$imagefile") && has_capability('moodle/site:config', context_system::instance())) {$link = '/filter/tex/texdebug.php';$action = null;} else {$link = new moodle_url('/filter/tex/displaytex.php', array('texexp'=>$tex));$action = new popup_action('click', $link, 'popup', array('width'=>320,'height'=>240));}$output = $OUTPUT->action_link($link, $anchorcontents, $action, array('title'=>'TeX')); //TODO: the popups do not work when text caching is enabled!!$output = "<span class=\"MathJax_Preview\">$output</span><script type=\"math/tex\">$tex</script>";return $output;}/*** TeX filtering class.*/class filter_tex extends moodle_text_filter {function filter($text, array $options = array()) {global $CFG, $DB;/// Do a quick check using stripos to avoid unnecessary workif ((!preg_match('/<tex/i', $text)) &&(strpos($text,'$$') === false) &&(strpos($text,'\\[') === false) &&(strpos($text, '\\(') === false) &&(!preg_match('/\[tex/i',$text))) {return $text;}# //restrict filtering to forum 130 (Maths Tools on moodle.org)# $scriptname = $_SERVER['SCRIPT_NAME'];# if (!strstr($scriptname,'/forum/')) {# return $text;# }# if (strstr($scriptname,'post.php')) {# $parent = forum_get_post_full($_GET['reply']);# $discussion = $DB->get_record("forum_discussions", array("id"=>$parent->discussion));# } else if (strstr($scriptname,'discuss.php')) {# $discussion = $DB->get_record("forum_discussions", array("id"=>$_GET['d']));# } else {# return $text;# }# if ($discussion->forum != 130) {# return $text;# }$text .= ' ';preg_match_all('/\$(\$\$+?)([^\$])/s',$text,$matches);for ($i=0; $i<count($matches[0]); $i++) {$replacement = str_replace('$','$', $matches[1][$i]).$matches[2][$i];$text = str_replace($matches[0][$i], $replacement, $text);}// <tex> TeX expression </tex>// or <tex alt="My alternative text to be used instead of the TeX form"> TeX expression </tex>// or $$ TeX expression $$// or \[ TeX expression \] // original tag of MathType and TeXaide (dlnsk)// or [tex] TeX expression [/tex] // somtime it's more comfortable than <tex> (dlnsk)$rules = array('<tex(?:\s+alt=["\'](.*?)["\'])?>(.+?)<\/tex>','\$\$(.+?)\$\$','\\\\\[(.+?)\\\\\]','\\\\\((.+?)\\\\\)','\\[tex\\](.+?)\\[\/tex\\]');$megarule = '/' . implode('|', $rules) . '/is';preg_match_all($megarule, $text, $matches);for ($i=0; $i<count($matches[0]); $i++) {$texexp = '';for ($j = 0; $j < count($rules); $j++) {$texexp .= $matches[$j + 2][$i];}$alt = $matches[1][$i];$texexp = str_replace('<nolink>','',$texexp);$texexp = str_replace('</nolink>','',$texexp);$texexp = str_replace('<span class="nolink">','',$texexp);$texexp = str_replace('</span>','',$texexp);$texexp = preg_replace("/<br[[:space:]]*\/?>/i", '', $texexp); //dlnsk$align = "middle";if (preg_match('/^align=bottom /',$texexp)) {$align = "text-bottom";$texexp = preg_replace('/^align=bottom /','',$texexp);} else if (preg_match('/^align=top /',$texexp)) {$align = "text-top";$texexp = preg_replace('/^align=top /','',$texexp);}// decode entities encoded by editor, luckily there is very little chance of double decoding$texexp = html_entity_decode($texexp, ENT_QUOTES, 'UTF-8');if ($texexp === '') {continue;}// Sanitize the decoded string, because filter_text_image() injects the final string between script tags.$texexp = clean_param($texexp, PARAM_TEXT);$md5 = md5($texexp);if (!$DB->record_exists("cache_filters", array("filter"=>"tex", "md5key"=>$md5))) {$texcache = new stdClass();$texcache->filter = 'tex';$texcache->version = 1;$texcache->md5key = $md5;$texcache->rawtext = $texexp;$texcache->timemodified = time();$DB->insert_record("cache_filters", $texcache, false);}$convertformat = get_config('filter_tex', 'convertformat');if ($convertformat == 'svg' && !core_useragent::supports_svg()) {$convertformat = 'png';}$filename = $md5.".{$convertformat}";$text = str_replace( $matches[0][$i], filter_text_image($filename, $texexp, 0, 0, $align, $alt), $text);}return $text;}}