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<?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 //
/////////////////////////////////////////////////////////////////////////////
$CFG->texfilterdir = "filter/tex";
function string_file_picture_tex($imagefile, $tex= "", $height="", $width="", $align="middle") {
// Given the path to a picture file in a course, or a URL,
// this function includes the picture in the page.
global $CFG;
$output = "";
if ($tex) {
$tex = str_replace('&','&amp;',$tex);
$tex = str_replace('<','&lt;',$tex);
$tex = str_replace('>','&gt;',$tex);
$tex = str_replace('"','&quot;',$tex);
$tex = str_replace("\'",'&#39;',$tex);
$title = "title=\"$tex\"";
}
if ($height) {
$height = "height=\"$height\"";
}
if ($width) {
$width = "width=\"$width\"";
}
if ($imagefile) {
if (!file_exists("$CFG->dataroot/$CFG->texfilterdir/$imagefile") && isadmin()) {
$output .= "<a href=\"$CFG->wwwroot/$CFG->texfilterdir/texdebug.php\">";
} else {
$output .= "<a target=\"popup\" title=\"TeX\" href=";
$output .= "\"$CFG->wwwroot/$CFG->texfilterdir/displaytex.php?";
$output .= urlencode($tex) . "\" onclick=\"return openpopup('/$CFG->texfilterdir/displaytex.php?";
$output .= urlencode($tex) . "', 'popup', 'menubar=0,location=0,scrollbars,";
$output .= "resizable,width=300,height=240', 0);\">";
}
$output .= "<img border=\"0\" $title $height $width alt=\"\" src=\"";
if ($CFG->slasharguments) { // Use this method if possible for better caching
$output .= "$CFG->wwwroot/$CFG->texfilterdir/pix.php/$imagefile";
} else {
$output .= "$CFG->wwwroot/$CFG->texfilterdir/pix.php?file=$imagefile";
}
$output .= "\" style=\"vertical-align:$align\" />";
$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,'$$')) {
return $text;
}
# //restrict filtering to forum 130 (Maths Tools on moodle.org)
# $scriptname = $_SERVER['SCRIPT_NAME'];
# if (!strstr($scriptname,'/forum/')) {
# return $text;
# }
# if (strstr($scriptname,'post.php')) {
# $parent = forum_get_post_full($_GET['reply']);
# $discussion = get_record("forum_discussions","id",$parent->discussion);
# } else if (strstr($scriptname,'discuss.php')) {
# $discussion = get_record("forum_discussions","id",$_GET['d'] );
# } else {
# return $text;
# }
# if ($discussion->forum != 130) {
# return $text;
# }
$text .= ' ';
preg_match_all('/\$(\$\$+?)([^\$])/s',$text,$matches);
for ($i=0;$i<count($matches[0]);$i++) {
$replacement = str_replace('$','&#x00024;',$matches[1][$i]).$matches[2][$i];
$text = str_replace($matches[0][$i],$replacement,$text);
}
//if (isadmin()) { error_reporting (E_ALL); }; //for debugging
// <tex> TeX expression </tex>
// or $$ TeX expression $$
preg_match_all('/<tex>(.+?)<\/tex>|\$\$(.+?)\$\$/is', $text, $matches);
for ($i=0; $i<count($matches[0]); $i++) {
$texexp = $matches[1][$i] . $matches[2][$i];
$texexp = str_replace('<nolink>','',$texexp);
$texexp = str_replace('</nolink>','',$texexp);
$texexp = str_replace('<span class="nolink">','',$texexp);
$texexp = str_replace('</span>','',$texexp);
$align = "middle";
if (preg_match('/^align=bottom /',$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 . ".gif";
$text = str_replace( $matches[0][$i], string_file_picture_tex($filename, $texexp, '', '', $align), $text);
}
return $text;
}
?>
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