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<?PHP // $Id$
      // This function fetches math. images from the data directory
      // If not, it obtains the corresponding TeX expression from the cache_tex db table
      // and uses mimeTeX to create the image file

    $nomoodlecookie = true; // Because it interferes with caching

    require_once("../../config.php");


    $CFG->texfilterdir = "filter/tex";
    $CFG->teximagedir = "filter/tex";

    error_reporting(E_ALL);
    $query = urldecode($_SERVER['QUERY_STRING']);

    if ($query) {
      $output = $query;
      $splitpos = strpos($query,'&')-4;
      $texexp = substr($query,4,$splitpos);
      $md5 = md5($texexp);
      if (strpos($query,'ShowDB') || strpos($query,'DeleteDB')) {
$texcache = get_record("cache_filters","filter","tex", "md5key", $md5);
      }
      if (strpos($query,'ShowDB')) {
        if ($texcache) {
$output = "DB cache_filters entry for $texexp\n";
          $output .= "id = $texcache->id\n";
          $output .= "filter = $texcache->filter\n";
          $output .= "version = $texcache->version\n";
          $output .= "md5key = $texcache->md5key\n";
          $output .= "rawtext = $texcache->rawtext\n";
          $output .= "timemodified = $texcache->timemodified\n";
        } else {
          $output = "DB cache_filters entry for $texexp not found\n";
        }
      }
      if (strpos($query,'DeleteDB')) {
        if ($texcache) {
          $output = "Deleting DB cache_filters entry for $texexp\n";
          $result = delete_records("cache_filters","id",$texcache->id);
          if ($result) {
$result = 1;
          } else {
            $result = 0;
          }
          $output .= "Number of records deleted = $result\n";
        } else {
          $output = "Could not delete DB cache_filters entry for $texexp\nbecause it could not be found.\n";
        }
      }
      if (strpos($query,'ShowImage')) {
        tex2image($texexp);
      } else {
        outputText($output);
      }
      exit;
    }


function outputText($texexp) {
  header("Content-type: text/html");
  echo "<html><body><pre>\n";
  if ($texexp) {
    $texexp = str_replace('<','&lt;',$texexp);
    $texexp = str_replace('>','&gt;',$texexp);
    $texexp = str_replace('"','&quot;',$texexp);
    echo "$texexp\n\n";
  } else {
    echo "No text output available\n\n";
  }
  echo "</pre></body></html>\n";
}

function tex2image($texexp) {
  global $CFG;
  if ($texexp) {
       $texexp = '\Large ' . $texexp;
       $lifetime = 86400;
       $image = md5($texexp) . ".gif";
       $filetype = 'image/gif';
       if (!file_exists("$CFG->dataroot/$CFG->teximagedir")) {
          make_upload_directory($CFG->teximagedir);
       }
       $pathname = "$CFG->dataroot/$CFG->teximagedir/$image";
       $windows = 0;
         switch (PHP_OS) {
       case "Linux":
           $cmd = "$CFG->dirroot/$CFG->texfilterdir/mimetex.linux -e $pathname ". escapeshellarg($texexp);
       break;
       case "WINNT":
       case "WIN32":
       case "Windows":
           $windows = 1;
           $texexp = str_replace('"','\"',$texexp);
           $cmd = "$CFG->dirroot/$CFG->texfilterdir/mimetex.exe -e $pathname \"$texexp\"";
break;
case "Darwin":
$cmd = "$CFG->dirroot/$CFG->texfilterdir/mimetex.darwin -e $pathname ". escapeshellarg($texexp);
break;
}
system($cmd);
}
if ($texexp && file_exists($pathname)) {
$lastmodified = filemtime($pathname);
header("Last-Modified: " . gmdate("D, d M Y H:i:s", $lastmodified) . " GMT");
header("Expires: " . gmdate("D, d M Y H:i:s", time() + $lifetime) . " GMT");
header("Cache-control: max_age = $lifetime"); // a day
header("Pragma: ");
header("Content-disposition: inline; filename=$image");
header("Content-length: ".filesize($pathname));
header("Content-type: $filetype");
readfile("$pathname");
} else {
if (!$windows) {
$cmd = "$cmd 2>&1";
echo `$cmd` . "<br>\n";
}
echo "Image not found!";
}
}
?>

<html>
<head><title>TeX Filter Debugger</title></head>
<body>
<?PHP
require_once("../../config.php");
$filename = "$CFG->dirroot/filter/tex/pix.php";
$PHP_OS = PHP_OS;
$handle = fopen($filename,"r");
$contents = fread($handle, filesize($filename));
fclose($handle);
if (!strpos($contents,'case "'. $PHP_OS . '":')) {
echo "<b>WARNING!</b> case \"$PHP_OS\": NOT found in pix.php!!!<br><br>";
}
?>
<p>Please enter an algebraic expression <b>without</b> any surrounding $$ into
the text box below. (Click <a href="#help">here for help.</a>)
          <form action="texdebug.php" method="get"
           target="inlineframe">
            <center>
             <input type="text" name="tex" size=50
                    value="\Large f(x)=\Bigint_{-\infty}^x~e^{-t^2}dt">
            </center>
           <ol>
           <li>First click on this button <input type="submit" name="ShowDB" value="Show DB Entry">
               to see the cache_filters database entry for this expression.</li>
<li>If the database entry looks corrupt, click on this button to delete it:
               <input type="submit" name="DeleteDB" value="Delete DB Entry"></li>
           <li>Finally click on this button <input type="submit" name="ShowImage" value="Show Image">
               to show a graphic image of the algebraic expression.</li>
           </ol>
          </form> <br> <br>
       <center>
          <iframe name="inlineframe" align="middle" width="80%" height="200">
          &lt;p&gt;Something is wrong...&lt;/p&gt;
          </iframe>
       </center> <br>
<hr>
<a name="help">
<h2>Debugging Help</h2>
</a>
<p>First a brief overview of how the TeX filter works. The TeX filter first
searches the database cache_filters table to see if this TeX expression had been
processed before. If not, it adds a DB entry for that expression. It then
replaces the TeX expression by an &lt;img src=&quot;.../filter/tex/pix.php...&quot;&gt;
tag. The filter/tex/pix.php script then searches the database to find an
appropriate gif image file for that expression and to create one if it doesn't exist.
Here are a few common things that can go wrong and some suggestions on how
you might try to fix them.</p>
<ol>
<li>Something had gone wrong on a previous occasion when the filter tried to
process this expression. Then the database entry for that expression contains
a bad TeX expression in the rawtext field (usually blank). You can fix this
by clicking on &quot;Delete DB Entry&quot;</li>
<li>The TeX to gif image conversion process does not work. If your server is
running Unix, a likely cause is that the mimetex binary you are using is
incompatible with your operating system. You can try compiling it from the
C sources downloaded from <a href="http://www.forkosh.com/mimetex.zip">
http://www.forkosh.com/mimetex.zip</a>, or looking for an appropriate
binary at <a href="http://moodle.org/download/mimetex/">
http://moodle.org/download/mimetex/</a>. You may then also need to
edit your moodle/filter/tex/pix.php file to add
<br /><?PHP echo "case &quot;" . PHP_OS . "&quot;:" ;?><br ?> to the list of operating systems
in the switch (PHP_OS) statement. Windows users may have a problem properly
unzipping mimetex.exe. Make sure that mimetex.exe is is <b>PRECISELY</b>
328192 bytes in size. If not, download a fresh copy from
<a href="http://moodle.org/download/mimetex/windows/mimetex.exe">
http://moodle.org/download/mimetex/windows/mimetex.exe</a>.
Another possible problem which may affect
both Unix and Windows servers is that the web server doesn't have execute permission
on the mimetex binary. In that case change permissions accordingly</li>
</ol>
</body>
</html>
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