Proyectos de Subversion Moodle

<?php

// This file is part of Moodle - http://moodle.org/

//

// Moodle 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 3 of the License, or

// (at your option) any later version.

//

// Moodle 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.

//

// You should have received a copy of the GNU General Public License

// along with Moodle.  If not, see <http://www.gnu.org/licenses/>.

/**

 * Moodle - Filter for converting TeX expressions to cached gif images

 *

 * 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.

 *

 * @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 = "<img class=\"texrender\" $title alt=\"$alt\" src=\"";

    if ($CFG->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!!

    $output = "<span class=\"MathJax_Preview\">$output</span><script type=\"math/tex\">$tex</script>";

    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('/<tex/i', $text)) &&

                (strpos($text,'$$') === false) &&

                (strpos($text,'\\[') === false) &&

                (strpos($text, '\\(') === false) &&

                (!preg_match('/\[tex/i',$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 = $DB->get_record("forum_discussions", array("id"=>$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; $i<count($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)

        $rules = array(

            '<tex(?:\s+alt=["\'](.*?)["\'])?>(.+?)<\/tex>',

            '\$\$(.+?)\$\$',

            '\\\\\[(.+?)\\\\\]',

            '\\\\\((.+?)\\\\\)',

            '\\[tex\\](.+?)\\[\/tex\\]'

        );

        $megarule = '/' . implode('|', $rules) . '/is';

        preg_match_all($megarule, $text, $matches);

        for ($i=0; $i<count($matches[0]); $i++) {

            $texexp = '';

            for ($j = 0; $j < count($rules); $j++) {

                $texexp .= $matches[$j + 2][$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 = preg_replace("/<br[[:space:]]*\/?>/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;

            }

            // Sanitize the decoded string, because filter_text_image() injects the final string between script tags.

            $texexp = clean_param($texexp, PARAM_TEXT);

            $md5 = md5($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;

    }

}