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Differences Between: [Versions 310 and 401] [Versions 311 and 401] [Versions 39 and 401] [Versions 401 and 402] [Versions 401 and 403]

   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              // Construct directory structure.
  20              $this->temp_dir = make_request_directory();
  21          }
  22  
  23          /**
  24           * Old syntax of class constructor. Deprecated in PHP7.
  25           *
  26           * @deprecated since Moodle 3.1
  27           */
  28          public function latex() {
  29              debugging('Use of class name as constructor is deprecated', DEBUG_DEVELOPER);
  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              // $fontsize don't affects to formula's size. $density can change size
  49              $doc = "\\documentclass[{$fontsize}pt]{article}\n";
  50              $doc .= get_config('filter_tex', 'latexpreamble');
  51              $doc .= "\\pagestyle{empty}\n";
  52              $doc .= "\\begin{document}\n";
  53              if (preg_match("/^[[:space:]]*\\\\begin\\{(gather|align|alignat|multline).?\\}/i", $formula)) {
  54                 $doc .= "$formula\n";
  55              } else {
  56                 $doc .= "$ {$formula} $\n";
  57              }
  58              $doc .= "\\end{document}\n";
  59  
  60              // Sanitize the whole document (rather than just the formula) to make sure no one can bypass sanitization
  61              // by using \newcommand in preamble to give an alias to a blocked command.
  62              $doc = filter_tex_sanitize_formula($doc);
  63  
  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              $tex = "$filename.tex"; // Absolute paths won't work with openin_any = p setting.
 115              $dvi = "{$this->temp_dir}/$filename.dvi";
 116              $ps  = "{$this->temp_dir}/$filename.ps";
 117              $img = "{$this->temp_dir}/$filename.{$convertformat}";
 118  
 119              // Change directory to temp dir so that we can work with relative paths.
 120              chdir($this->temp_dir);
 121  
 122              // turn the latex doc into a .tex file in the temp area
 123              $fh = fopen( $tex, 'w' );
 124              fputs( $fh, $doc );
 125              fclose( $fh );
 126  
 127              // run latex on document
 128              $command = "$pathlatex --interaction=nonstopmode --halt-on-error $tex";
 129  
 130              if ($this->execute($command, $log)) { // It allways False on Windows
 131  //                return false;
 132              }
 133  
 134              // run dvips (.dvi to .ps)
 135              $pathdvips = escapeshellarg(trim(get_config('filter_tex', 'pathdvips'), " '\""));
 136              $command = "$pathdvips -q -E $dvi -o $ps";
 137              if ($this->execute($command, $log )) {
 138                  return false;
 139              }
 140  
 141              // Run convert on document (.ps to .gif/.png) or run dvisvgm (.ps to .svg).
 142              if ($background) {
 143                  $bg_opt = "-transparent \"$background\""; // Makes transparent background
 144              } else {
 145                  $bg_opt = "";
 146              }
 147              if ($convertformat == 'svg') {
 148                  $pathdvisvgm = escapeshellarg(trim(get_config('filter_tex', 'pathdvisvgm'), " '\""));
 149                  $command = "$pathdvisvgm -E $ps -o $img";
 150              } else {
 151                  $pathconvert = escapeshellarg(trim(get_config('filter_tex', 'pathconvert'), " '\""));
 152                  $command = "$pathconvert -density $density -trim $bg_opt $ps $img";
 153              }
 154              if ($this->execute($command, $log )) {
 155                  return false;
 156              }
 157  
 158              return $img;
 159          }
 160      }