filter/algebra/filter.php

   1 <?PHP
   2 /////////////////////////////////////////////////////////////////////////////
   3 //                                                                         //
   4 // NOTICE OF COPYRIGHT                                                     //
   5 //                                                                         //
   6 // Moodle - Filter for converting simple calculator-type algebraic        //
   7 // expressions to cached gif images                                        //
   8 //                                                                         //
   9 // Copyright (C) 2004 Zbigniew Fiedorowicz fiedorow@math.ohio-state.edu    //
  10 // Originally based on code provided by Bruno Vernier bruno@vsbeducation.ca//
  11 // This program is free software; you can redistribute it and/or modify    //
  12 // it under the terms of the GNU General Public License as published by    //
  13 // the Free Software Foundation; either version 2 of the License, or       //
  14 // (at your option) any later version.                                     //
  15 //                                                                         //
  16 // This program is distributed in the hope that it will be useful,         //
  17 // but WITHOUT ANY WARRANTY; without even the implied warranty of          //
  18 // MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the           //
  19 // GNU General Public License for more details:                            //
  20 //                                                                         //
  21 //          http://www.gnu.org/copyleft/gpl.html                           //
  22 //                                                                         //
  23 /////////////////////////////////////////////////////////////////////////////
  24 //-------------------------------------------------------------------------
  25 // NOTE: This Moodle text filter converts algebraic expressions delimited
  26 // by either @@...@@ or by <algebra...>...</algebra> tags
  27 // first converts it to TeX using WeBWorK algebra parser Perl library
  28 // AlgParser.pm, part of the WeBWorK distribution obtained from
  29 // http://webhost.math.rochester.edu/downloadwebwork/
  30 // then converts the TeX to gif images using
  31 // mimetex.cgi obtained from http://www.forkosh.com/mimetex.html authored by
  32 // John Forkosh john@forkosh.com. The mimetex.cgi ELF binary compiled for Linux i386
  33 // as well as AlgParser.pm are included with this distribution.
  34 // Note that there may be patent restrictions on the production of gif images
  35 // in Canada and some parts of Western Europe and Japan until July 2004.
  36 //-------------------------------------------------------------------------
  37 // You will then need to edit your moodle/config.php to invoke mathml_filter.php
  38 //-------------------------------------------------------------------------
  39
  40
  41 /// Edit these lines to correspond to your installation
  42 // File path to the directory where mathml_filter.php resides
  43     $CFG->algebrafilterdir = "filter/algebra";
  44     $CFG->texfilterdir = "filter/tex";
  45     if ( (PHP_OS == "WINNT") || (PHP_OS == "WIN32") || (PHP_OS == "Windows") ) {
  46       $CFG->algebrafilterdirwin = "filter\\algebra";
  47     }
  48
  49 function string_file_picture_algebra($imagefile, $tex= "", $height="", $width="", $align="middle") {
  50   // Given the path to a picture file in a course, or a URL,
  51   // this function includes the picture in the page.
  52   global $CFG;
  53
  54   $output = "";
  55   $origtex = $tex;
  56   $style = 'style="border:0px; vertical-align:'.$align.';';
  57   if ($tex) {
  58     $tex = str_replace('&','&amp;',$tex);
  59     $tex = str_replace('<','&lt;',$tex);
  60     $tex = str_replace('>','&gt;',$tex);
  61     $tex = str_replace('"','&quot;',$tex);
  62     $tex = str_replace("\'",'&#39;',$tex);
  63     $title = "title=\"$tex\"";
  64   }
  65   if ($height) {
  66     $style .= " height:{$height}px;";
  67   }
  68   if ($width) {
  69     $style .= " width:{$width}px;";
  70   }
  71   $style .= '"';
  72   if ($imagefile) {
  73     if (!file_exists("$CFG->dataroot/$CFG->algebrafilterdir/$imagefile") && has_capability('moodle/site:config', get_context_instance(CONTEXT_SYSTEM, SITEID))) {
  74       $output .= "<a href=\"$CFG->wwwroot/$CFG->algebrafilterdir/algebradebug.php\">";
  75     } else {
  76       $output .= "<a target=\"popup\" title=\"TeX\" href=";
  77       $output .= "\"$CFG->wwwroot/$CFG->texfilterdir/displaytex.php?";
  78       $output .= urlencode($tex) . "\" onclick=\"return openpopup('/$CFG->texfilterdir/displaytex.php?";
  79       $output .= urlencode($tex) . "', 'popup', 'menubar=0,location=0,scrollbars,";
  80       $output .= "resizable,width=300,height=240', 0);\">";
  81     }
  82     $output .= "<img $title alt=\"".s($origtex)."\" src=\"";
  83     if ($CFG->slasharguments) {        // Use this method if possible for better caching
  84       $output .= "$CFG->wwwroot/$CFG->algebrafilterdir/pix.php/$imagefile";
  85     } else {
  86       $output .= "$CFG->wwwroot/$CFG->algebrafilterdir/pix.php?file=$imagefile";
  87     }
  88     $output .= "\" $style />";
  89     $output .= "</a>";
  90   } else {
  91     $output .= "Error: must pass URL or course";
  92   }
  93   return $output;
  94 }
  95
  96
  97 function algebra_filter ($courseid, $text) {
  98
  99     global $CFG;
 100
 101     /// Do a quick check using stripos to avoid unnecessary wor
 102     if (!preg_match('/<algebra/i',$text) && !strstr($text,'@@')) {
 103         return $text;
 104     }
 105
 106 #    //restrict filtering to forum 130 (Maths Tools on moodle.org)
 107 #    $scriptname = $_SERVER['SCRIPT_NAME'];
 108 #    if (!strstr($scriptname,'/forum/')) {
 109 #        return $text;
 110 #    }
 111 #    if (strstr($scriptname,'post.php')) {
 112 #        $parent = forum_get_post_full($_GET['reply']);
 113 #        $discussion = get_record("forum_discussions","id",$parent->discussion);
 114 #    } else if (strstr($scriptname,'discuss.php')) {
 115 #        $discussion = get_record("forum_discussions","id",$_GET['d'] );
 116 #    } else {
 117 #        return $text;
 118 #    }
 119 #    if ($discussion->forum != 130) {
 120 #        return $text;
 121 #    }
 122
 123
 124     $text .= ' ';
 125
 126     preg_match_all('/@(@@+)([^@])/',$text,$matches);
 127     for ($i=0;$i<count($matches[0]);$i++) {
 128         $replacement = str_replace('@','&#x00040;',$matches[1][$i]).$matches[2][$i];
 129         $text = str_replace($matches[0][$i],$replacement,$text);
 130     }
 131
 132     // <algebra> some algebraic input expression </algebra>
 133     // or @@ some algebraic input expression @@
 134
 135     preg_match_all('/<algebra>(.+?)<\/algebra>|@@(.+?)@@/is', $text, $matches);
 136     for ($i=0; $i<count($matches[0]); $i++) {
 137         $algebra = $matches[1][$i] . $matches[2][$i];
 138         $algebra = str_replace('<nolink>','',$algebra);
 139         $algebra = str_replace('</nolink>','',$algebra);
 140         $algebra = str_replace('<span class="nolink">','',$algebra);
 141         $algebra = str_replace('</span>','',$algebra);
 142         $align = "middle";
 143         if (preg_match('/^align=bottom /',$algebra)) {
 144           $align = "text-bottom";
 145           $algebra = preg_replace('/^align=bottom /','',$algebra);
 146         } else if (preg_match('/^align=top /',$algebra)) {
 147           $align = "text-top";
 148           $algebra = preg_replace('/^align=top /','',$algebra);
 149         }
 150         $md5 =  md5($algebra);
 151         $filename =  $md5  . ".gif";
 152         if (! $texcache = get_record("cache_filters","filter","algebra", "md5key", $md5)) {
 153            $algebra = str_replace('&lt;','<',$algebra);
 154            $algebra = str_replace('&gt;','>',$algebra);
 155            $algebra = str_replace('<>','#',$algebra);
 156            $algebra = str_replace('<=','%',$algebra);
 157            $algebra = str_replace('>=','!',$algebra);
 158            $algebra = preg_replace('/([=><%!#] *)-/',"\$1 zeroplace -",$algebra);
 159            $algebra = str_replace('delta','zdelta',$algebra);
 160            $algebra = str_replace('beta','bita',$algebra);
 161            $algebra = str_replace('theta','thita',$algebra);
 162            $algebra = str_replace('zeta','zita',$algebra);
 163            $algebra = str_replace('eta','xeta',$algebra);
 164            $algebra = str_replace('epsilon','zepslon',$algebra);
 165            $algebra = str_replace('upsilon','zupslon',$algebra);
 166            $algebra = preg_replace('!\r\n?!',' ',$algebra);
 167            $algebra = escapeshellarg($algebra);
 168            if ( (PHP_OS == "WINNT") || (PHP_OS == "WIN32") || (PHP_OS == "Windows") ) {
 169               $cmd  = "cd $CFG->dirroot\\$CFG->algebrafilterdirwin & algebra2tex.pl $algebra";
 170            } else {
 171               $cmd  = "cd $CFG->dirroot/$CFG->algebrafilterdir; ./algebra2tex.pl $algebra";
 172            }
 173            $texexp = `$cmd`;
 174            if (preg_match('/parsehilight/',$texexp)) {
 175              $text = str_replace( $matches[0][$i],"<b>Syntax error:</b> " . $texexp,$text);
 176            } else if ($texexp) {
 177               $texexp = str_replace('zeroplace','',$texexp);
 178               $texexp = str_replace('#','\not= ',$texexp);
 179               $texexp = str_replace('%','\leq ',$texexp);
 180               $texexp = str_replace('!','\geq ',$texexp);
 181               $texexp = str_replace('\left{','{',$texexp);
 182               $texexp = str_replace('\right}','}',$texexp);
 183               $texexp = str_replace('\fun',' ',$texexp);
 184               $texexp = str_replace('infty','\infty',$texexp);
 185               $texexp = str_replace('alpha','\alpha',$texexp);
 186               $texexp = str_replace('gamma','\gamma',$texexp);
 187               $texexp = str_replace('iota','\iota',$texexp);
 188               $texexp = str_replace('kappa','\kappa',$texexp);
 189               $texexp = str_replace('lambda','\lambda',$texexp);
 190               $texexp = str_replace('mu','\mu',$texexp);
 191               $texexp = str_replace('nu','\nu',$texexp);
 192               $texexp = str_replace('xi','\xi',$texexp);
 193               $texexp = str_replace('rho','\rho',$texexp);
 194               $texexp = str_replace('sigma','\sigma',$texexp);
 195               $texexp = str_replace('tau','\tau',$texexp);
 196               $texexp = str_replace('phi','\phi',$texexp);
 197               $texexp = str_replace('chi','\chi',$texexp);
 198               $texexp = str_replace('psi','\psi',$texexp);
 199               $texexp = str_replace('omega','\omega',$texexp);
 200               $texexp = str_replace('zdelta','\delta',$texexp);
 201               $texexp = str_replace('bita','\beta',$texexp);
 202               $texexp = str_replace('thita','\theta',$texexp);
 203               $texexp = str_replace('zita','\zeta',$texexp);
 204               $texexp = str_replace('xeta','\eta',$texexp);
 205               $texexp = str_replace('zepslon','\epsilon',$texexp);
 206               $texexp = str_replace('zupslon','\upsilon',$texexp);
 207               $texexp = str_replace('\mbox{logten}','\mbox{log}_{10}',$texexp);
 208               $texexp = str_replace('\mbox{acos}','\mbox{cos}^{-1}',$texexp);
 209               $texexp = str_replace('\mbox{asin}','\mbox{sin}^{-1}',$texexp);
 210               $texexp = str_replace('\mbox{atan}','\mbox{tan}^{-1}',$texexp);
 211               $texexp = str_replace('\mbox{asec}','\mbox{sec}^{-1}',$texexp);
 212               $texexp = str_replace('\mbox{acsc}','\mbox{csc}^{-1}',$texexp);
 213               $texexp = str_replace('\mbox{acot}','\mbox{cot}^{-1}',$texexp);
 214               $texexp = str_replace('\mbox{acosh}','\mbox{cosh}^{-1}',$texexp);
 215               $texexp = str_replace('\mbox{asinh}','\mbox{sinh}^{-1}',$texexp);
 216               $texexp = str_replace('\mbox{atanh}','\mbox{tanh}^{-1}',$texexp);
 217               $texexp = str_replace('\mbox{asech}','\mbox{sech}^{-1}',$texexp);
 218               $texexp = str_replace('\mbox{acsch}','\mbox{csch}^{-1}',$texexp);
 219               $texexp = str_replace('\mbox{acoth}','\mbox{coth}^{-1}',$texexp);
 220               //$texexp = preg_replace('/\\\frac{(.+?)}{\\\left\((.+?)\\\right\)}/s','\frac{'."\$1}{\$2}",$texexp);
 221               $texexp = preg_replace('/\\\sqrt{(.+?),(.+?)}/s','\sqrt['. "\$2]{\$1}",$texexp);
 222               $texexp = preg_replace('/\\\mbox{abs}\\\left\((.+?)\\\right\)/s',"|\$1|",$texexp);
 223               $texexp = preg_replace('/\\\log\\\left\((.+?),(.+?)\\\right\)/s','\log_{'. "\$2}\\left(\$1\\right)",$texexp);
 224               $texexp = preg_replace('/(\\\cos|\\\sin|\\\tan|\\\sec|\\\csc|\\\cot)([h]*)\\\left\((.+?),(.+?)\\\right\)/s',"\$1\$2^{". "\$4}\\left(\$3\\right)",$texexp);
 225               $texexp = preg_replace('/\\\int\\\left\((.+?),(.+?),(.+?)\\\right\)/s','\int_'. "{\$2}^{\$3}\$1 ",$texexp);
 226               $texexp = preg_replace('/\\\int\\\left\((.+?d[a-z])\\\right\)/s','\int '. "\$1 ",$texexp);
 227               $texexp = preg_replace('/\\\lim\\\left\((.+?),(.+?),(.+?)\\\right\)/s','\lim_'. "{\$2\\to \$3}\$1 ",$texexp);
 228               $texcache->filter = 'algebra';
 229               $texcache->version = 1;
 230               $texcache->md5key = $md5;
 231               $texcache->rawtext = addslashes($texexp);
 232               $texcache->timemodified = time();
 233               insert_record("cache_filters",$texcache, false);
 234               $text = str_replace( $matches[0][$i], string_file_picture_algebra($filename, $texexp, '', '', $align), $text);
 235            } else {
 236               $text = str_replace( $matches[0][$i],"<b>Undetermined error:</b> ",$text);
 237            }
 238         } else {
 239            $text = str_replace( $matches[0][$i], string_file_picture_algebra($filename, $texcache->rawtext), $text);
 240         }
 241     }
 242     return $text;
 243 }
 244
 245 ?>