Support/Comments for mimeTeX

/*
mimeTeX Plugin
===================

This plugin lets you easily embed LaTeX math in your html pages.
Version: 0.2, 2007-04-01, Luca Allulli
Version: 0.2.1, 2007-02-01, Daniele "MadMage" Calisi
Version: 0.5.1, 2007-06-08, Americo Dias
Version: 0.5.2, 2007-11-01, Yacoby

Authors: Luca Allulli, Americo Dias
        http://www.amdias.com

License: CC-GNU LGPL
        http://creativecommons.org/licenses/LGPL/2.1/

MODx version: 0.9.5

See mimeTeX.txt for details.
 */
 
/* <?php */

// Please install mimetex CGI on your own server and update the following line.
$mimetex_url = 'http://www.example.com/cgi-bin/mimetex.cgi';

// Change the following line if you want to change the cache formulas. Don't forget to have write permitions!
$cache_folder = 'assets/cache/';

// Grab and evluate the document event.
$mdStrEvent = &$modx->Event;

if ( $mdStrEvent->name == "OnWebPagePrerender" ){
                        
        // Grab the raw document output.
        $mdStrDocOutput = $modx->documentOutput;

        // Search the raw document output for blocks to be parsed. Those blocks are marked with <markdown> and </markdown> tags.
        preg_match_all( "|<pre class=\"math\">(.*)</pre>|Uis", $mdStrDocOutput, $mdArrParseBlocks);

        // Get the parsed output for each block.

        // If no blocks found, exit
        if( count($mdArrParseBlocks) == 0 ){
                return;
        }
                                                
        // Process the formulas...
        for ( $i=0; $i<count( $mdArrParseBlocks[0] ); $i++ ){
                $mdBlock = $mdArrParseBlocks[0][$i];
                        
                // Create a unique formula filename using the formula text and MD5
                $formula_text = $mdArrParseBlocks[1][$i];
                $formula_hash = md5($formula_text);
                $formula_filename = 'etx_'.$formula_hash.'.gif';
                        
                $cache_formula_path = $modx->config['base_path'] . $cache_folder . $formula_filename;
                $cache_formula_url = $modx->config['site_url'] . $cache_folder . $formula_filename;
                        
                // Is the formula image cached?
                if (!is_file($cache_formula_path)){
                        // If not, create the image
                        $mimetex_host = curl_init($mimetex_url . '?formdata=' . urlencode($formula_text));

                        // and save it to the cache path
                        $cache_file = fopen($cache_formula_path, 'w');
                        curl_setopt($mimetex_host, CURLOPT_FILE, $cache_file);
                        curl_setopt($mimetex_host, CURLOPT_HEADER, 0);
                        curl_exec($mimetex_host);
                        curl_close($mimetex_host);
                        fclose($cache_file);
                }
                        
                $mdBlockText = '<img src="' . $cache_formula_url . '" alt="'.$formula_text.'"  border=0 align=middle>';
                $mdStrDocOutput = str_replace( $mdBlock, $mdBlockText, $mdStrDocOutput );
        }

        // Overwrite the raw document output with parsed one.
        $modx->documentOutput = $mdStrDocOutput;
}
/* ?> */