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214 lines
8.2 KiB
214 lines
8.2 KiB
2 years ago
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<?php
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// This file is part of Moodle - http://moodle.org/
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//
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// Moodle is free software: you can redistribute it and/or modify
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// it under the terms of the GNU General Public License as published by
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// the Free Software Foundation, either version 3 of the License, or
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// (at your option) any later version.
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//
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// Moodle is distributed in the hope that it will be useful,
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// but WITHOUT ANY WARRANTY; without even the implied warranty of
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// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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// GNU General Public License for more details.
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//
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// You should have received a copy of the GNU General Public License
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// along with Moodle. If not, see <http://www.gnu.org/licenses/>.
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/**
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* Moodle - Filter for converting TeX expressions to cached gif images
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*
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* This Moodle text filter converts TeX expressions delimited
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* by either $$...$$ or by <tex...>...</tex> tags to gif images using
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* mimetex.cgi obtained from http: *www.forkosh.com/mimetex.html authored by
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* John Forkosh john@forkosh.com. Several binaries of this areincluded with
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* this distribution.
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* Note that there may be patent restrictions on the production of gif images
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* in Canada and some parts of Western Europe and Japan until July 2004.
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*
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* @package filter
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* @subpackage tex
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* @copyright 2004 Zbigniew Fiedorowicz fiedorow@math.ohio-state.edu
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* Originally based on code provided by Bruno Vernier bruno@vsbeducation.ca
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* @license http://www.gnu.org/copyleft/gpl.html GNU GPL v3 or later
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*/
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defined('MOODLE_INTERNAL') || die;
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require_once($CFG->libdir . '/classes/useragent.php');
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/**
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* Create TeX image link.
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*
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* @param string $imagefile name of file
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* @param string $tex TeX notation (html entities already decoded)
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* @param int $height O means automatic
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* @param int $width O means automatic
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* @param string $align
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* @param string $alt
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* @return string HTML markup
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*/
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function filter_text_image($imagefile, $tex, $height, $width, $align, $alt) {
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global $CFG, $OUTPUT;
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if (!$imagefile) {
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throw new coding_exception('image file argument empty in filter_text_image()');
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}
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// Work out any necessary inline style.
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$rules = array();
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if ($align !== 'middle') {
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$rules[] = 'vertical-align:' . $align . ';';
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}
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if ($height) {
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$rules[] = 'height:' . $height . 'px;';
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}
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if ($width) {
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$rules[] = 'width:' . $width . 'px;';
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}
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if (!empty($rules)) {
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$style = ' style="' . implode('', $rules) . '" ';
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} else {
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$style = '';
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}
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// Prepare the title attribute.
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// Note that we retain the title tag as TeX format rather than using
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// the alt text, even if supplied. The alt text is intended for blind
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// users (to provide a text equivalent to the equation) while the title
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// is there as a convenience for sighted users who want to see the TeX
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// code.
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$title = 'title="'.s($tex).'"';
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if ($alt === '') {
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$alt = s($tex);
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} else {
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$alt = s(html_entity_decode($tex, ENT_QUOTES, 'UTF-8'));
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}
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// Build the output.
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$anchorcontents = "<img class=\"texrender\" $title alt=\"$alt\" src=\"";
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if ($CFG->slasharguments) { // Use this method if possible for better caching
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$anchorcontents .= "$CFG->wwwroot/filter/tex/pix.php/$imagefile";
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} else {
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$anchorcontents .= "$CFG->wwwroot/filter/tex/pix.php?file=$imagefile";
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}
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$anchorcontents .= "\" $style/>";
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if (!file_exists("$CFG->dataroot/filter/tex/$imagefile") && has_capability('moodle/site:config', context_system::instance())) {
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$link = '/filter/tex/texdebug.php';
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$action = null;
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} else {
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$link = new moodle_url('/filter/tex/displaytex.php', array('texexp'=>$tex));
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$action = new popup_action('click', $link, 'popup', array('width'=>320,'height'=>240));
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}
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$output = $OUTPUT->action_link($link, $anchorcontents, $action, array('title'=>'TeX')); //TODO: the popups do not work when text caching is enabled!!
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$output = "<span class=\"MathJax_Preview\">$output</span><script type=\"math/tex\">$tex</script>";
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return $output;
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}
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/**
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* TeX filtering class.
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*/
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class filter_tex extends moodle_text_filter {
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function filter($text, array $options = array()) {
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global $CFG, $DB;
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/// Do a quick check using stripos to avoid unnecessary work
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if ((!preg_match('/<tex/i', $text)) &&
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(strpos($text,'$$') === false) &&
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(strpos($text,'\\[') === false) &&
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(strpos($text, '\\(') === false) &&
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(!preg_match('/\[tex/i',$text))) {
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return $text;
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}
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# //restrict filtering to forum 130 (Maths Tools on moodle.org)
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# $scriptname = $_SERVER['SCRIPT_NAME'];
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# if (!strstr($scriptname,'/forum/')) {
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# return $text;
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# }
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# if (strstr($scriptname,'post.php')) {
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# $parent = forum_get_post_full($_GET['reply']);
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# $discussion = $DB->get_record("forum_discussions", array("id"=>$parent->discussion));
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# } else if (strstr($scriptname,'discuss.php')) {
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# $discussion = $DB->get_record("forum_discussions", array("id"=>$_GET['d']));
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# } else {
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# return $text;
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# }
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# if ($discussion->forum != 130) {
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# return $text;
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# }
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$text .= ' ';
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preg_match_all('/\$(\$\$+?)([^\$])/s',$text,$matches);
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for ($i=0; $i<count($matches[0]); $i++) {
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$replacement = str_replace('$','$', $matches[1][$i]).$matches[2][$i];
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$text = str_replace($matches[0][$i], $replacement, $text);
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}
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// <tex> TeX expression </tex>
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// or <tex alt="My alternative text to be used instead of the TeX form"> TeX expression </tex>
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// or $$ TeX expression $$
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// or \[ TeX expression \] // original tag of MathType and TeXaide (dlnsk)
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// or [tex] TeX expression [/tex] // somtime it's more comfortable than <tex> (dlnsk)
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$rules = array(
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'<tex(?:\s+alt=["\'](.*?)["\'])?>(.+?)<\/tex>',
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'\$\$(.+?)\$\$',
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'\\\\\[(.+?)\\\\\]',
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'\\\\\((.+?)\\\\\)',
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'\\[tex\\](.+?)\\[\/tex\\]'
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);
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$megarule = '/' . implode($rules, '|') . '/is';
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preg_match_all($megarule, $text, $matches);
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for ($i=0; $i<count($matches[0]); $i++) {
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$texexp = '';
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for ($j = 0; $j < count($rules); $j++) {
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$texexp .= $matches[$j + 2][$i];
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}
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$alt = $matches[1][$i];
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$texexp = str_replace('<nolink>','',$texexp);
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$texexp = str_replace('</nolink>','',$texexp);
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$texexp = str_replace('<span class="nolink">','',$texexp);
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$texexp = str_replace('</span>','',$texexp);
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$texexp = preg_replace("/<br[[:space:]]*\/?>/i", '', $texexp); //dlnsk
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$align = "middle";
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if (preg_match('/^align=bottom /',$texexp)) {
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$align = "text-bottom";
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$texexp = preg_replace('/^align=bottom /','',$texexp);
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} else if (preg_match('/^align=top /',$texexp)) {
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$align = "text-top";
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$texexp = preg_replace('/^align=top /','',$texexp);
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}
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// decode entities encoded by editor, luckily there is very little chance of double decoding
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$texexp = html_entity_decode($texexp, ENT_QUOTES, 'UTF-8');
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if ($texexp === '') {
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continue;
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}
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$md5 = md5($texexp);
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if (!$DB->record_exists("cache_filters", array("filter"=>"tex", "md5key"=>$md5))) {
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$texcache = new stdClass();
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$texcache->filter = 'tex';
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$texcache->version = 1;
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$texcache->md5key = $md5;
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$texcache->rawtext = $texexp;
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$texcache->timemodified = time();
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$DB->insert_record("cache_filters", $texcache, false);
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}
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$convertformat = get_config('filter_tex', 'convertformat');
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if ($convertformat == 'svg' && !core_useragent::supports_svg()) {
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$convertformat = 'png';
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}
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$filename = $md5.".{$convertformat}";
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$text = str_replace( $matches[0][$i], filter_text_image($filename, $texexp, 0, 0, $align, $alt), $text);
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}
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return $text;
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}
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}
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