. /** * Moodle - Filter for converting TeX expressions to cached gif images * * This Moodle text filter converts TeX expressions delimited * by either $$...$$ or by ... 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. * * @package filter * @subpackage tex * @copyright 2004 Zbigniew Fiedorowicz fiedorow@math.ohio-state.edu * Originally based on code provided by Bruno Vernier bruno@vsbeducation.ca * @license http://www.gnu.org/copyleft/gpl.html GNU GPL v3 or later */ defined('MOODLE_INTERNAL') || die; require_once($CFG->libdir . '/classes/useragent.php'); /** * Create TeX image link. * * @param string $imagefile name of file * @param string $tex TeX notation (html entities already decoded) * @param int $height O means automatic * @param int $width O means automatic * @param string $align * @param string $alt * @return string HTML markup */ function filter_text_image($imagefile, $tex, $height, $width, $align, $alt) { global $CFG, $OUTPUT; if (!$imagefile) { throw new coding_exception('image file argument empty in filter_text_image()'); } // 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. // 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. $title = 'title="'.s($tex).'"'; if ($alt === '') { $alt = s($tex); } else { $alt = s(html_entity_decode($tex, ENT_QUOTES, 'UTF-8')); } // Build the output. $anchorcontents = "slasharguments) { // Use this method if possible for better caching $anchorcontents .= "$CFG->wwwroot/filter/tex/pix.php/$imagefile"; } else { $anchorcontents .= "$CFG->wwwroot/filter/tex/pix.php?file=$imagefile"; } $anchorcontents .= "\" $style/>"; if (!file_exists("$CFG->dataroot/filter/tex/$imagefile") && has_capability('moodle/site:config', context_system::instance())) { $link = '/filter/tex/texdebug.php'; $action = null; } else { $link = new moodle_url('/filter/tex/displaytex.php', array('texexp'=>$tex)); $action = new popup_action('click', $link, 'popup', array('width'=>320,'height'=>240)); } $output = $OUTPUT->action_link($link, $anchorcontents, $action, array('title'=>'TeX')); //TODO: the popups do not work when text caching is enabled!! $output = "$output"; return $output; } /** * TeX filtering class. */ class filter_tex extends moodle_text_filter { function filter($text, array $options = array()) { global $CFG, $DB; /// Do a quick check using stripos to avoid unnecessary work if ((!preg_match('/get_record("forum_discussions", array("id"=>$parent->discussion)); # } else if (strstr($scriptname,'discuss.php')) { # $discussion = $DB->get_record("forum_discussions", array("id"=>$_GET['d'])); # } else { # return $text; # } # if ($discussion->forum != 130) { # return $text; # } $text .= ' '; preg_match_all('/\$(\$\$+?)([^\$])/s',$text,$matches); for ($i=0; $i TeX expression // or TeX expression // or $$ TeX expression $$ // or \[ TeX expression \] // original tag of MathType and TeXaide (dlnsk) // or [tex] TeX expression [/tex] // somtime it's more comfortable than (dlnsk) $rules = array( '(.+?)<\/tex>', '\$\$(.+?)\$\$', '\\\\\[(.+?)\\\\\]', '\\\\\((.+?)\\\\\)', '\\[tex\\](.+?)\\[\/tex\\]' ); $megarule = '/' . implode($rules, '|') . '/is'; preg_match_all($megarule, $text, $matches); for ($i=0; $i','',$texexp); $texexp = str_replace('','',$texexp); $texexp = str_replace('','',$texexp); $texexp = str_replace('','',$texexp); $texexp = preg_replace("//i", '', $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); } // decode entities encoded by editor, luckily there is very little chance of double decoding $texexp = html_entity_decode($texexp, ENT_QUOTES, 'UTF-8'); if ($texexp === '') { continue; } $md5 = md5($texexp); if (!$DB->record_exists("cache_filters", array("filter"=>"tex", "md5key"=>$md5))) { $texcache = new stdClass(); $texcache->filter = 'tex'; $texcache->version = 1; $texcache->md5key = $md5; $texcache->rawtext = $texexp; $texcache->timemodified = time(); $DB->insert_record("cache_filters", $texcache, false); } $convertformat = get_config('filter_tex', 'convertformat'); if ($convertformat == 'svg' && !core_useragent::supports_svg()) { $convertformat = 'png'; } $filename = $md5.".{$convertformat}"; $text = str_replace( $matches[0][$i], filter_text_image($filename, $texexp, 0, 0, $align, $alt), $text); } return $text; } }