Proyectos de Subversion Moodle

<?php

    // latex.php

    // render TeX stuff using latex - this will not work on all platforms

    // or configurations. Only works on Linux and Mac with appropriate

    // software installed.

    // Much of this inspired/copied from Benjamin Zeiss' work

    class latex {

        var $temp_dir;

        var $error;

        /** @var bool To store value of supported_platform. */

        protected $supported_platform;

        /**

         * Constructor - create temporary directories and build paths to

         * external 'helper' binaries.

         * Other platforms could/should be added

         */

        public function __construct() {

            // Construct directory structure.

            $this->temp_dir = make_request_directory();

        }

        /**

         * Old syntax of class constructor. Deprecated in PHP7.

         *

         * @deprecated since Moodle 3.1

         */

        public function latex() {

            debugging('Use of class name as constructor is deprecated', DEBUG_DEVELOPER);

            self::__construct();

        }

        /**

         * Accessor function for support_platform field.

         * @return boolean value of supported_platform

         */

        function supported() {

            return $this->supported_platform;

        }

        /**

         * Turn the bit of TeX into a valid latex document

         * @param string $forumula the TeX formula

         * @param int $fontsize the font size

         * @return string the latex document

         */

        function construct_latex_document($formula, $fontsize = 12) {

            // $fontsize don't affects to formula's size. $density can change size

            $doc = "\\documentclass[{$fontsize}pt]{article}\n";

            $doc .= get_config('filter_tex', 'latexpreamble');

            $doc .= "\\pagestyle{empty}\n";

            $doc .= "\\begin{document}\n";

            if (preg_match("/^[[:space:]]*\\\\begin\\{(gather|align|alignat|multline).?\\}/i", $formula)) {

               $doc .= "$formula\n";

            } else {

               $doc .= "$ {$formula} $\n";

            }

            $doc .= "\\end{document}\n";

            // Sanitize the whole document (rather than just the formula) to make sure no one can bypass sanitization

            // by using \newcommand in preamble to give an alias to a blocked command.

            $doc = filter_tex_sanitize_formula($doc);

            return $doc;

        }

        /**

         * execute an external command, with optional logging

         * @param string $command command to execute

         * @param file $log valid open file handle - log info will be written to this file

         * @return return code from execution of command

         */

        function execute($command, $log=null ) {

            $output = array();

            exec( $command, $output, $return_code );

            if ($log) {

                fwrite( $log, "COMMAND: $command \n" );

                $outputs = implode( "\n", $output );

                fwrite( $log, "OUTPUT: $outputs \n" );

                fwrite( $log, "RETURN_CODE: $return_code\n " );

            }

            return $return_code;

        }

        /**

         * Render TeX string into gif/png

         * @param string $formula TeX formula

         * @param string $filename filename for output (including extension)

         * @param int $fontsize font size

         * @param int $density density value for .ps to .gif/.png conversion

         * @param string $background background color (e.g, #FFFFFF).

         * @param file $log valid open file handle for optional logging (debugging only)

         * @return bool true if successful

         */

        function render($formula, $filename, $fontsize=12, $density=240, $background='', $log=null ) {

            global $CFG;

            // quick check - will this work?

            $pathlatex = get_config('filter_tex', 'pathlatex');

            if (empty($pathlatex)) {

                return false;

            }

            $pathlatex = escapeshellarg(trim($pathlatex, " '\""));

            $doc = $this->construct_latex_document( $formula, $fontsize );

            // construct some file paths

            $convertformat = get_config('filter_tex', 'convertformat');

            if (!strpos($filename, ".{$convertformat}")) {

                $convertformat = 'png';

            }

            $filename = str_replace(".{$convertformat}", '', $filename);

            $tex = "$filename.tex"; // Absolute paths won't work with openin_any = p setting.

            $dvi = "{$this->temp_dir}/$filename.dvi";

            $ps  = "{$this->temp_dir}/$filename.ps";

            $img = "{$this->temp_dir}/$filename.{$convertformat}";

            // Change directory to temp dir so that we can work with relative paths.

            chdir($this->temp_dir);

            // turn the latex doc into a .tex file in the temp area

            $fh = fopen( $tex, 'w' );

            fputs( $fh, $doc );

            fclose( $fh );

            // run latex on document

            $command = "$pathlatex --interaction=nonstopmode --halt-on-error $tex";

            if ($this->execute($command, $log)) { // It allways False on Windows

//                return false;

            }

            // run dvips (.dvi to .ps)

            $pathdvips = escapeshellarg(trim(get_config('filter_tex', 'pathdvips'), " '\""));

            $command = "$pathdvips -q -E $dvi -o $ps";

            if ($this->execute($command, $log )) {

                return false;

            }

            // Run convert on document (.ps to .gif/.png) or run dvisvgm (.ps to .svg).

            if ($background) {

                $bg_opt = "-transparent \"$background\""; // Makes transparent background

            } else {

                $bg_opt = "";

            }

            if ($convertformat == 'svg') {

                $pathdvisvgm = escapeshellarg(trim(get_config('filter_tex', 'pathdvisvgm'), " '\""));

                $command = "$pathdvisvgm -E $ps -o $img";

            } else {

                $pathconvert = escapeshellarg(trim(get_config('filter_tex', 'pathconvert'), " '\""));

                $command = "$pathconvert -density $density -trim $bg_opt $ps $img";

            }

            if ($this->execute($command, $log )) {

                return false;

            }

            return $img;

        }

    }