/filter/tex/filter.php
PHP | 173 lines | 96 code | 11 blank | 66 comment | 19 complexity | 141ebc2a3a45a41caed62b9b515fc628 MD5 | raw file
Possible License(s): BSD-3-Clause, LGPL-2.0, LGPL-2.1
- <?PHP
- /////////////////////////////////////////////////////////////////////////////
- // //
- // NOTICE OF COPYRIGHT //
- // //
- // Moodle - Filter for converting TeX expressions to cached gif images //
- // //
- // Copyright (C) 2004 Zbigniew Fiedorowicz fiedorow@math.ohio-state.edu //
- // Originally based on code provided by Bruno Vernier bruno@vsbeducation.ca//
- // This program 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 2 of the License, or //
- // (at your option) any later version. //
- // //
- // This program 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: //
- // //
- // http://www.gnu.org/copyleft/gpl.html //
- // //
- /////////////////////////////////////////////////////////////////////////////
- //-------------------------------------------------------------------------
- // NOTE: 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.
- //-------------------------------------------------------------------------
- /////////////////////////////////////////////////////////////////////////////
- // To activate this filter, add a line like this to your //
- // list of filters in your Filter configuration: //
- // //
- // filter/tex/filter.php //
- /////////////////////////////////////////////////////////////////////////////
-
- function string_file_picture_tex($imagefile, $tex= "", $height="", $width="", $align="middle", $alt='') {
- global $CFG;
-
- if ($alt==='') {
- $alt = s($tex);
- }
-
- // 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 {
- $style = '';
- }
-
- // Prepare the title attribute.
- if ($tex) {
- $tex = str_replace('&','&',$tex);
- $tex = str_replace('<','<',$tex);
- $tex = str_replace('>','>',$tex);
- $tex = str_replace('"','"',$tex);
- $tex = str_replace("\'",''',$tex);
- // 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.
- $title = "title=\"$tex\"";
- }
-
- // Build the output.
- $output = "";
- if ($imagefile) {
- if (!file_exists("$CFG->dataroot/filter/tex/$imagefile") && has_capability('moodle/site:config', get_context_instance(CONTEXT_SYSTEM))) {
- $output .= "<a href=\"$CFG->wwwroot/filter/tex/texdebug.php\">";
- } else {
- $output .= "<a target=\"popup\" title=\"TeX\" href=";
- $output .= "\"$CFG->wwwroot/filter/tex/displaytex.php?";
- $output .= urlencode($tex) . "\" onclick=\"return openpopup('/filter/tex/displaytex.php?";
- $output .= urlencode($tex) . "', 'popup', 'menubar=0,location=0,scrollbars,";
- $output .= "resizable,width=300,height=240', 0);\">";
- }
- $output .= "<img class=\"texrender\" $title alt=\"$alt\" src=\"";
- if ($CFG->slasharguments) { // Use this method if possible for better caching
- $output .= "$CFG->wwwroot/filter/tex/pix.php/$imagefile";
- } else {
- $output .= "$CFG->wwwroot/filter/tex/pix.php?file=$imagefile";
- }
- $output .= "\" $style/>";
- $output .= "</a>";
- } else {
- $output .= "Error: must pass URL or course";
- }
- return $output;
- }
-
- function tex_filter ($courseid, $text) {
-
- global $CFG;
-
- /// Do a quick check using stripos to avoid unnecessary work
- if (!preg_match('/<tex/i',$text) and !strstr($text,'$$') and !strstr($text,'\\[') and !preg_match('/\[tex/i',$text)) { //added one more tag (dlnsk)
- 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']);
- # $discussion = get_record("forum_discussions","id",$parent->discussion);
- # } else if (strstr($scriptname,'discuss.php')) {
- # $discussion = get_record("forum_discussions","id",$_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)
- preg_match_all('/<tex(?:\s+alt=["\'](.*?)["\'])?>(.+?)<\/tex>|\$\$(.+?)\$\$|\\\\\[(.+?)\\\\\]|\\[tex\\](.+?)\\[\/tex\\]/is', $text, $matches);
- for ($i=0; $i<count($matches[0]); $i++) {
- $texexp = $matches[2][$i] . $matches[3][$i] . $matches[4][$i] . $matches[5][$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 = eregi_replace("<br[[:space:]]*\/?>", '', $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);
- }
- $md5 = md5($texexp);
- if (! $texcache = get_record("cache_filters","filter","tex", "md5key", $md5)) {
- $texcache->filter = 'tex';
- $texcache->version = 1;
- $texcache->md5key = $md5;
- $texcache->rawtext = addslashes($texexp);
- $texcache->timemodified = time();
- insert_record("cache_filters",$texcache, false);
- }
- $filename = $md5 . ".{$CFG->filter_tex_convertformat}";
- $text = str_replace( $matches[0][$i], string_file_picture_tex($filename, $texexp, '', '', $align, $alt), $text);
- }
- return $text;
- }
-
- ?>