Inaki
cf4e7548a8
It seems some TeX installs use a convert utility that renders poor quality images when using the GIF format, but render good ones when using PNG. If all the needed tools are available, let the admin choose the preferred output format. Merged from MOODLE_19_STABLE
176 lines
8.4 KiB
PHP
176 lines
8.4 KiB
PHP
<?PHP
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/////////////////////////////////////////////////////////////////////////////
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// //
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// NOTICE OF COPYRIGHT //
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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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// Copyright (C) 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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// This program 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 2 of the License, or //
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// (at your option) any later version. //
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// //
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// This program 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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// http://www.gnu.org/copyleft/gpl.html //
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// //
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/////////////////////////////////////////////////////////////////////////////
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//-------------------------------------------------------------------------
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// NOTE: 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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/////////////////////////////////////////////////////////////////////////////
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// To activate this filter, add a line like this to your //
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// list of filters in your Filter configuration: //
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// //
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// filter/tex/filter.php //
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/////////////////////////////////////////////////////////////////////////////
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function string_file_picture_tex($imagefile, $tex= "", $height="", $width="", $align="middle", $alt='') {
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global $CFG;
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if ($alt==='') {
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$alt = s($tex);
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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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if ($tex) {
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$tex = str_replace('&','&',$tex);
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$tex = str_replace('<','<',$tex);
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$tex = str_replace('>','>',$tex);
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$tex = str_replace('"','"',$tex);
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$tex = str_replace("\'",''',$tex);
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// Note that we retain the title tag as TeX format rather than using
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// the alt text, even if supplied. The alt text is intended for blind
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// users (to provide a text equivalent to the equation) while the title
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// is there as a convenience for sighted users who want to see the TeX
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// code.
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$title = "title=\"$tex\"";
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}
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// Build the output.
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$output = "";
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if ($imagefile) {
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if (!file_exists("$CFG->dataroot/filter/tex/$imagefile") && has_capability('moodle/site:config', get_context_instance(CONTEXT_SYSTEM))) {
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$output .= "<a href=\"$CFG->wwwroot/filter/tex/texdebug.php\">";
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} else {
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$output .= "<a target=\"popup\" title=\"TeX\" href=";
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$output .= "\"$CFG->wwwroot/filter/tex/displaytex.php?";
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$output .= urlencode($tex) . "\" onclick=\"return openpopup('/filter/tex/displaytex.php?";
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$output .= urlencode($tex) . "', 'popup', 'menubar=0,location=0,scrollbars,";
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$output .= "resizable,width=300,height=240', 0);\">";
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}
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$output .= "<img class=\"texrender\" $title alt=\"$alt\" src=\"";
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if ($CFG->slasharguments) { // Use this method if possible for better caching
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$output .= "$CFG->wwwroot/filter/tex/pix.php/$imagefile";
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} else {
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$output .= "$CFG->wwwroot/filter/tex/pix.php?file=$imagefile";
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}
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$output .= "\" $style/>";
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$output .= "</a>";
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} else {
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$output .= "Error: must pass URL or course";
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}
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return $output;
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}
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class tex_filter extends moodle_text_filter {
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function filter ($text) {
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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) and !strstr($text,'$$') and !strstr($text,'\\[') and !preg_match('/\[tex/i',$text)) { //added one more tag (dlnsk)
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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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preg_match_all('/<tex(?:\s+alt=["\'](.*?)["\'])?>(.+?)<\/tex>|\$\$(.+?)\$\$|\\\\\[(.+?)\\\\\]|\\[tex\\](.+?)\\[\/tex\\]/is', $text, $matches);
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for ($i=0; $i<count($matches[0]); $i++) {
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$texexp = $matches[2][$i] . $matches[3][$i] . $matches[4][$i] . $matches[5][$i];
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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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$md5 = md5($texexp);
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if (! $texcache = $DB->get_record("cache_filters", array("filter"=>"tex", "md5key"=>$md5))) {
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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", $texcache, false);
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}
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$filename = $md5 . ".{$CFG->filter_tex_convertformat}";
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$text = str_replace( $matches[0][$i], string_file_picture_tex($filename, $texexp, '', '', $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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