filter/tex/filter.php

   1 <?PHP
   2 /////////////////////////////////////////////////////////////////////////////
   3 //                                                                         //
   4 // NOTICE OF COPYRIGHT                                                     //
   5 //                                                                         //
   6 // Moodle - Filter for converting TeX expressions to cached gif images     //
   7 //                                                                         //
   8 // Copyright (C) 2004 Zbigniew Fiedorowicz fiedorow@math.ohio-state.edu    //
   9 // Originally based on code provided by Bruno Vernier bruno@vsbeducation.ca//
  10 // This program is free software; you can redistribute it and/or modify    //
  11 // it under the terms of the GNU General Public License as published by    //
  12 // the Free Software Foundation; either version 2 of the License, or       //
  13 // (at your option) any later version.                                     //
  14 //                                                                         //
  15 // This program is distributed in the hope that it will be useful,         //
  16 // but WITHOUT ANY WARRANTY; without even the implied warranty of          //
  17 // MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the           //
  18 // GNU General Public License for more details:                            //
  19 //                                                                         //
  20 //          http://www.gnu.org/copyleft/gpl.html                           //
  21 //                                                                         //
  22 /////////////////////////////////////////////////////////////////////////////
  23 //-------------------------------------------------------------------------
  24 // NOTE: This Moodle text filter converts TeX expressions delimited
  25 // by either $$...$$ or by <tex...>...</tex> tags to gif images using
  26 // mimetex.cgi obtained from http://www.forkosh.com/mimetex.html authored by
  27 // John Forkosh john@forkosh.com.  Several binaries of this areincluded with
  28 // this distribution.
  29 // Note that there may be patent restrictions on the production of gif images
  30 // in Canada and some parts of Western Europe and Japan until July 2004.
  31 //-------------------------------------------------------------------------
  32 /////////////////////////////////////////////////////////////////////////////
  33 //  To activate this filter, add a line like this to your                  //
  34 //  list of filters in your Filter configuration:                          //
  35 //                                                                         //
  36 //       filter/tex/filter.php                                             //
  37 /////////////////////////////////////////////////////////////////////////////
  38
  39 function string_file_picture_tex($imagefile, $tex= "", $height="", $width="", $align="middle", $alt='') {
  40     if($alt==='') {
  41         $alt=s($tex);
  42     }
  43 // Given the path to a picture file in a course, or a URL,
  44     // this function includes the picture in the page.
  45     global $CFG;
  46
  47     $output = "";
  48     $origtex = $tex;
  49     $style = 'style="border:0px; vertical-align:'.$align.';';
  50     if ($tex) {
  51         $tex = str_replace('&','&amp;',$tex);
  52         $tex = str_replace('<','&lt;',$tex);
  53         $tex = str_replace('>','&gt;',$tex);
  54         $tex = str_replace('"','&quot;',$tex);
  55         $tex = str_replace("\'",'&#39;',$tex);
  56         // Note that we retain the title tag as TeX format rather than using
  57         // the alt text, even if supplied. The alt text is intended for blind
  58         // users (to provide a text equivalent to the equation) while the title
  59         // is there as a convenience for sighted users who want to see the TeX
  60         // code.
  61         $title = "title=\"$tex\"";
  62     }
  63     if ($height) {
  64         $style .= " height:{$height}px;";
  65     }
  66     if ($width) {
  67         $style .= " width:{$width}px;";
  68     }
  69     $style .= '"';
  70     if ($imagefile) {
  71         if (!file_exists("$CFG->dataroot/filter/tex/$imagefile") && has_capability('moodle/site:config', get_context_instance(CONTEXT_SYSTEM))) {
  72           $output .= "<a href=\"$CFG->wwwroot/filter/tex/texdebug.php\">";
  73         } else {
  74           $output .= "<a target=\"popup\" title=\"TeX\" href=";
  75           $output .= "\"$CFG->wwwroot/filter/tex/displaytex.php?";
  76           $output .= urlencode($tex) . "\" onclick=\"return openpopup('/filter/tex/displaytex.php?";
  77           $output .= urlencode($tex) . "', 'popup', 'menubar=0,location=0,scrollbars,";
  78           $output .= "resizable,width=300,height=240', 0);\">";
  79         }
  80         $output .= "<img class=\"texrender\" $title alt=\"$alt\" src=\"";
  81         if ($CFG->slasharguments) {        // Use this method if possible for better caching
  82             $output .= "$CFG->wwwroot/filter/tex/pix.php/$imagefile";
  83         } else {
  84             $output .= "$CFG->wwwroot/filter/tex/pix.php?file=$imagefile";
  85         }
  86         $output .= "\" $style />";
  87         $output .= "</a>";
  88     } else {
  89         $output .= "Error: must pass URL or course";
  90     }
  91     return $output;
  92 }
  93
  94 function tex_filter ($courseid, $text) {
  95
  96     global $CFG;
  97
  98     /// Do a quick check using stripos to avoid unnecessary work
  99     if (!preg_match('/<tex/i',$text) and !strstr($text,'$$') and !strstr($text,'\\[') and !preg_match('/\[tex/i',$text)) { //added one more tag (dlnsk)
 100         return $text;
 101     }
 102
 103 #    //restrict filtering to forum 130 (Maths Tools on moodle.org)
 104 #    $scriptname = $_SERVER['SCRIPT_NAME'];
 105 #    if (!strstr($scriptname,'/forum/')) {
 106 #        return $text;
 107 #    }
 108 #    if (strstr($scriptname,'post.php')) {
 109 #        $parent = forum_get_post_full($_GET['reply']);
 110 #        $discussion = get_record("forum_discussions","id",$parent->discussion);
 111 #    } else if (strstr($scriptname,'discuss.php')) {
 112 #        $discussion = get_record("forum_discussions","id",$_GET['d'] );
 113 #    } else {
 114 #        return $text;
 115 #    }
 116 #    if ($discussion->forum != 130) {
 117 #        return $text;
 118 #    }
 119     $text .= ' ';
 120     preg_match_all('/\$(\$\$+?)([^\$])/s',$text,$matches);
 121     for ($i=0;$i<count($matches[0]);$i++) {
 122         $replacement = str_replace('$','&#x00024;',$matches[1][$i]).$matches[2][$i];
 123         $text = str_replace($matches[0][$i],$replacement,$text);
 124     }
 125
 126     // <tex> TeX expression </tex>
 127     // or <tex alt="My alternative text to be used instead of the TeX form"> TeX expression </tex>
 128     // or $$ TeX expression $$
 129     // or \[ TeX expression \]          // original tag of MathType and TeXaide (dlnsk)
 130     // or [tex] TeX expression [/tex]   // somtime it's more comfortable than <tex> (dlnsk)
 131     preg_match_all('/<tex(?:\s+alt=["\'](.*?)["\'])?>(.+?)<\/tex>|\$\$(.+?)\$\$|\\\\\[(.+?)\\\\\]|\\[tex\\](.+?)\\[\/tex\\]/is', $text, $matches);
 132     for ($i=0; $i<count($matches[0]); $i++) {
 133         $texexp = $matches[2][$i] . $matches[3][$i] . $matches[4][$i] . $matches[5][$i];
 134         $alt = $matches[1][$i];
 135         $texexp = str_replace('<nolink>','',$texexp);
 136         $texexp = str_replace('</nolink>','',$texexp);
 137         $texexp = str_replace('<span class="nolink">','',$texexp);
 138         $texexp = str_replace('</span>','',$texexp);
 139         $texexp = eregi_replace("<br[[:space:]]*\/?>", '', $texexp);  //dlnsk
 140         $align = "middle";
 141         if (preg_match('/^align=bottom /',$texexp)) {
 142           $align = "text-bottom";
 143           $texexp = preg_replace('/^align=bottom /','',$texexp);
 144         } else if (preg_match('/^align=top /',$texexp)) {
 145           $align = "text-top";
 146           $texexp = preg_replace('/^align=top /','',$texexp);
 147         }
 148         $md5 = md5($texexp);
 149         if (! $texcache = get_record("cache_filters","filter","tex", "md5key", $md5)) {
 150             $texcache->filter = 'tex';
 151             $texcache->version = 1;
 152             $texcache->md5key = $md5;
 153             $texcache->rawtext = addslashes($texexp);
 154             $texcache->timemodified = time();
 155             insert_record("cache_filters",$texcache, false);
 156         }
 157         $filename = $md5 . ".gif";
 158         $text = str_replace( $matches[0][$i], string_file_picture_tex($filename, $texexp, '', '', $align, $alt), $text);
 159     }
 160     return $text;
 161 }
 162
 163 ?>