filter/tex/latex.php

   1 <?php
   2     // latex.php
   3     // render TeX stuff using latex - this will not work on all platforms
   4     // or configurations. Only works on Linux and Mac with appropriate
   5     // software installed.
   6     // Much of this inspired/copied from Benjamin Zeiss' work
   7
   8     class latex {
   9
  10         var $temp_dir;
  11         var $error;
  12
  13         /**
  14          * Constructor - create temporary directories and build paths to
  15          * external 'helper' binaries.
  16          * Other platforms could/should be added
  17          */
  18         function latex() {
  19             global $CFG;
  20
  21             // construct directory structure
  22             $this->temp_dir = $CFG->tempdir . "/latex";
  23             make_temp_directory('latex');
  24         }
  25
  26         /**
  27          * Accessor function for support_platform field.
  28          * @return boolean value of supported_platform
  29          */
  30         function supported() {
  31             return $this->supported_platform;
  32         }
  33
  34         /**
  35          * Turn the bit of TeX into a valid latex document
  36          * @param string $forumula the TeX formula
  37          * @param int $fontsize the font size
  38          * @return string the latex document
  39          */
  40         function construct_latex_document( $formula, $fontsize=12 ) {
  41             global $CFG;
  42
  43             $formula = filter_tex_sanitize_formula($formula);
  44
  45             // $fontsize don't affects to formula's size. $density can change size
  46             $doc =  "\\documentclass[{$fontsize}pt]{article}\n";
  47             $doc .= get_config('filter_tex', 'latexpreamble');
  48             $doc .= "\\pagestyle{empty}\n";
  49             $doc .= "\\begin{document}\n";
  50 //dlnsk            $doc .= "$ {$formula} $\n";
  51             if (preg_match("/^[[:space:]]*\\\\begin\\{(gather|align|alignat|multline).?\\}/i",$formula)) {
  52                $doc .= "$formula\n";
  53             } else {
  54                $doc .= "$ {$formula} $\n";
  55             }
  56             $doc .= "\\end{document}\n";
  57             return $doc;
  58         }
  59
  60         /**
  61          * execute an external command, with optional logging
  62          * @param string $command command to execute
  63          * @param file $log valid open file handle - log info will be written to this file
  64          * @return return code from execution of command
  65          */
  66         function execute( $command, $log=null ) {
  67             $output = array();
  68             exec( $command, $output, $return_code );
  69             if ($log) {
  70                 fwrite( $log, "COMMAND: $command \n" );
  71                 $outputs = implode( "\n", $output );
  72                 fwrite( $log, "OUTPUT: $outputs \n" );
  73                 fwrite( $log, "RETURN_CODE: $return_code\n " );
  74             }
  75             return $return_code;
  76         }
  77
  78         /**
  79          * Render TeX string into gif/png
  80          * @param string $formula TeX formula
  81          * @param string $filename base of filename for output (no extension)
  82          * @param int $fontsize font size
  83          * @param int $density density value for .ps to .gif/.png conversion
  84          * @param string $background background color (e.g, #FFFFFF).
  85          * @param file $log valid open file handle for optional logging (debugging only)
  86          * @return bool true if successful
  87          */
  88         function render( $formula, $filename, $fontsize=12, $density=240, $background='', $log=null ) {
  89
  90             global $CFG;
  91
  92             // quick check - will this work?
  93             $pathlatex = get_config('filter_tex', 'pathlatex');
  94             if (empty($pathlatex)) {
  95                 return false;
  96             }
  97
  98             $doc = $this->construct_latex_document( $formula, $fontsize );
  99
 100             // construct some file paths
 101             $tex = "{$this->temp_dir}/$filename.tex";
 102             $dvi = "{$this->temp_dir}/$filename.dvi";
 103             $ps  = "{$this->temp_dir}/$filename.ps";
 104             $convertformat = get_config('filter_tex', 'convertformat');
 105             $img = "{$this->temp_dir}/$filename.{$convertformat}";
 106
 107             // turn the latex doc into a .tex file in the temp area
 108             $fh = fopen( $tex, 'w' );
 109             fputs( $fh, $doc );
 110             fclose( $fh );
 111
 112             // run latex on document
 113             $command = "{$pathlatex} --interaction=nonstopmode --halt-on-error $tex";
 114             chdir( $this->temp_dir );
 115             if ($this->execute($command, $log)) { // It allways False on Windows
 116 //                return false;
 117             }
 118
 119             // run dvips (.dvi to .ps)
 120             $pathdvips = get_config('filter_tex', 'pathdvips');
 121             $command = "{$pathdvips} -E $dvi -o $ps";
 122             if ($this->execute($command, $log )) {
 123                 return false;
 124             }
 125
 126             // run convert on document (.ps to .gif/.png)
 127             if ($background) {
 128                 $bg_opt = "-transparent \"$background\""; // Makes transparent background
 129             } else {
 130                 $bg_opt = "";
 131             }
 132             $pathconvert = get_config('filter_tex', 'pathconvert');
 133             $command = "{$pathconvert} -density $density -trim $bg_opt $ps $img";
 134             if ($this->execute($command, $log )) {
 135                 return false;
 136             }
 137
 138             return $img;
 139         }
 140
 141         /**
 142          * Delete files created in temporary area
 143          * Don't forget to copy the final gif/png before calling this
 144          * @param string $filename file base (no extension)
 145          */
 146         function clean_up( $filename ) {
 147             global $CFG;
 148
 149             unlink( "{$this->temp_dir}/$filename.tex" );
 150             unlink( "{$this->temp_dir}/$filename.dvi" );
 151             unlink( "{$this->temp_dir}/$filename.ps" );
 152             $convertformat = get_config('filter_tex', 'convertformat');
 153             unlink( "{$this->temp_dir}/$filename.{$convertformat}" );
 154             unlink( "{$this->temp_dir}/$filename.aux" );
 155             unlink( "{$this->temp_dir}/$filename.log" );
 156             return;
 157         }
 158
 159     }
 160
 161
 162