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         public function __construct() {
  19             global $CFG;
  20
  21             // construct directory structure
  22             $this->temp_dir = $CFG->tempdir . "/latex";
  23             make_temp_directory('latex');
  24         }
  25
  26         /**
  27          * Old syntax of class constructor. Deprecated in PHP7.
  28          */
  29         public function latex() {
  30             self::__construct();
  31         }
  32
  33         /**
  34          * Accessor function for support_platform field.
  35          * @return boolean value of supported_platform
  36          */
  37         function supported() {
  38             return $this->supported_platform;
  39         }
  40
  41         /**
  42          * Turn the bit of TeX into a valid latex document
  43          * @param string $forumula the TeX formula
  44          * @param int $fontsize the font size
  45          * @return string the latex document
  46          */
  47         function construct_latex_document( $formula, $fontsize=12 ) {
  48             global $CFG;
  49
  50             $formula = filter_tex_sanitize_formula($formula);
  51
  52             // $fontsize don't affects to formula's size. $density can change size
  53             $doc =  "\\documentclass[{$fontsize}pt]{article}\n";
  54             $doc .= get_config('filter_tex', 'latexpreamble');
  55             $doc .= "\\pagestyle{empty}\n";
  56             $doc .= "\\begin{document}\n";
  57 //dlnsk            $doc .= "$ {$formula} $\n";
  58             if (preg_match("/^[[:space:]]*\\\\begin\\{(gather|align|alignat|multline).?\\}/i",$formula)) {
  59                $doc .= "$formula\n";
  60             } else {
  61                $doc .= "$ {$formula} $\n";
  62             }
  63             $doc .= "\\end{document}\n";
  64             return $doc;
  65         }
  66
  67         /**
  68          * execute an external command, with optional logging
  69          * @param string $command command to execute
  70          * @param file $log valid open file handle - log info will be written to this file
  71          * @return return code from execution of command
  72          */
  73         function execute( $command, $log=null ) {
  74             $output = array();
  75             exec( $command, $output, $return_code );
  76             if ($log) {
  77                 fwrite( $log, "COMMAND: $command \n" );
  78                 $outputs = implode( "\n", $output );
  79                 fwrite( $log, "OUTPUT: $outputs \n" );
  80                 fwrite( $log, "RETURN_CODE: $return_code\n " );
  81             }
  82             return $return_code;
  83         }
  84
  85         /**
  86          * Render TeX string into gif/png
  87          * @param string $formula TeX formula
  88          * @param string $filename filename for output (including extension)
  89          * @param int $fontsize font size
  90          * @param int $density density value for .ps to .gif/.png conversion
  91          * @param string $background background color (e.g, #FFFFFF).
  92          * @param file $log valid open file handle for optional logging (debugging only)
  93          * @return bool true if successful
  94          */
  95         function render( $formula, $filename, $fontsize=12, $density=240, $background='', $log=null ) {
  96
  97             global $CFG;
  98
  99             // quick check - will this work?
 100             $pathlatex = get_config('filter_tex', 'pathlatex');
 101             if (empty($pathlatex)) {
 102                 return false;
 103             }
 104             $pathlatex = escapeshellarg(trim($pathlatex, " '\""));
 105
 106             $doc = $this->construct_latex_document( $formula, $fontsize );
 107
 108             // construct some file paths
 109             $convertformat = get_config('filter_tex', 'convertformat');
 110             if (!strpos($filename, ".{$convertformat}")) {
 111                 $convertformat = 'png';
 112             }
 113             $filename = str_replace(".{$convertformat}", '', $filename);
 114             $tex = "{$this->temp_dir}/$filename.tex";
 115             $dvi = "{$this->temp_dir}/$filename.dvi";
 116             $ps  = "{$this->temp_dir}/$filename.ps";
 117             $img = "{$this->temp_dir}/$filename.{$convertformat}";
 118
 119             // turn the latex doc into a .tex file in the temp area
 120             $fh = fopen( $tex, 'w' );
 121             fputs( $fh, $doc );
 122             fclose( $fh );
 123
 124             // run latex on document
 125             $command = "$pathlatex --interaction=nonstopmode --halt-on-error $tex";
 126             chdir( $this->temp_dir );
 127             if ($this->execute($command, $log)) { // It allways False on Windows
 128 //                return false;
 129             }
 130
 131             // run dvips (.dvi to .ps)
 132             $pathdvips = escapeshellarg(trim(get_config('filter_tex', 'pathdvips'), " '\""));
 133             $command = "$pathdvips -E $dvi -o $ps";
 134             if ($this->execute($command, $log )) {
 135                 return false;
 136             }
 137
 138             // Run convert on document (.ps to .gif/.png) or run dvisvgm (.ps to .svg).
 139             if ($background) {
 140                 $bg_opt = "-transparent \"$background\""; // Makes transparent background
 141             } else {
 142                 $bg_opt = "";
 143             }
 144             if ($convertformat == 'svg') {
 145                 $pathdvisvgm = escapeshellarg(trim(get_config('filter_tex', 'pathdvisvgm'), " '\""));
 146                 $command = "$pathdvisvgm -E $ps -o $img";
 147             } else {
 148                 $pathconvert = escapeshellarg(trim(get_config('filter_tex', 'pathconvert'), " '\""));
 149                 $command = "$pathconvert -density $density -trim $bg_opt $ps $img";
 150             }
 151             if ($this->execute($command, $log )) {
 152                 return false;
 153             }
 154
 155             return $img;
 156         }
 157
 158         /**
 159          * Delete files created in temporary area
 160          * Don't forget to copy the final gif/png before calling this
 161          * @param string $filename file base (no extension)
 162          */
 163         function clean_up( $filename ) {
 164             global $CFG;
 165
 166             unlink( "{$this->temp_dir}/$filename.tex" );
 167             unlink( "{$this->temp_dir}/$filename.dvi" );
 168             unlink( "{$this->temp_dir}/$filename.ps" );
 169             $convertformat = get_config('filter_tex', 'convertformat');
 170             unlink( "{$this->temp_dir}/$filename.{$convertformat}" );
 171             unlink( "{$this->temp_dir}/$filename.aux" );
 172             unlink( "{$this->temp_dir}/$filename.log" );
 173             return;
 174         }
 175
 176     }
 177
 178
 179