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2006-07-19T05:34:40Z

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BR at 02:15, 24 March 2006

2006-03-24T02:15:09Z

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<pre>
<nowiki>
<?php

/**
* LaTeX Rendering Class
* Copyright (C) 2003 Benjamin Zeiss <zeiss@math.uni-goettingen.de>
*
* This library is free software; you can redistribute it and/or
* modify it under the terms of the GNU Lesser General Public
* License as published by the Free Software Foundation; either
* version 2.1 of the License, or (at your option) any later version.
*
* This library is distributed in the hope that it will be useful,
* but WITHOUT ANY WARRANTY; without even the implied warranty of
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
* Lesser General Public License for more details.
*
* You should have received a copy of the GNU Lesser General Public
* License along with this library; if not, write to the Free Software
* Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA
* --------------------------------------------------------------------
* @author Benjamin Zeiss <zeiss@math.uni-goettingen.de>
* @version v0.8
* @package latexrender
*
*/

/**
* Error code:
* 1. Too long formulas
* 2. formula contains tags in the blacklist
* 3. formula incorrect, can't be render
* 4. can't exec tex command
* maybe directory unwritable,can't create temporary files
* 5. formula image too big
* 6. can't copy image file to cahed formula directory
* maybe ImageMagick fail
*/

class LatexRender {

// ====================================================================================
// Variable Definitions
// ====================================================================================
var $_picture_path = "";
var $_picture_path_httpd = "";
var $_tmp_dir = "";
// i was too lazy to write mutator functions for every single program used
// just access it outside the class or change it here if nescessary
var $_latex_path = 'latex.exe';
var $_dvips_path = 'dvips.exe';
var $_convert_path = 'convert.exe';
var $_identify_path = 'identify.exe';

var $_formula_density = 120;
var $_xsize_limit = 700;
var $_ysize_limit = 700;
var $_string_length_limit = 800;
var $_font_size = 10;
var $_latexclass = "article"; //install extarticle class if you wish to have smaller font sizes
var $_tmp_filename;
var $_image_format = "gif"; //change to png if you prefer
// this most certainly needs to be extended. in the long term it is planned to use
// a positive list for more security. this is hopefully enough for now. i'd be glad
// to receive more bad tags !
var $_latex_tags_blacklist = array(
"include","def","command","loop","repeat","open","toks","output","input",
"catcode","name","^^",
"\\every","\\errhelp","\\errorstopmode","\\scrollmode","\\nonstopmode","\\batchmode",
"\\read","\\write","csname","\\newhelp","\\uppercase", "\\lowercase","\\relax","\\aftergroup",
"\\afterassignment","\\expandafter","\\noexpand","\\special"
);
var $_errorcode = 0;
var $_errorextra = "";

// ====================================================================================
// constructor
// ====================================================================================

/**
* Initializes the class
*
* @param string path where the rendered pictures should be stored
* @param string same path, but from the httpd chroot
*/
function LatexRender($picture_path,$picture_path_httpd,$tmp_dir) {
$this->_picture_path = $picture_path;
$this->_picture_path_httpd = $picture_path_httpd;
$this->_tmp_dir = $tmp_dir;
$this->_tmp_filename = md5(rand());
}

// ====================================================================================
// public functions
// ====================================================================================

/**
* Picture path Mutator function
*
* @param string sets the current picture path to a new location
*/
function setPicturePath($name) {
$this->_picture_path = $name;
}

/**
* Picture path Mutator function
*
* @returns the current picture path
*/
function getPicturePath() {
return $this->_picture_path;
}

/**
* Picture path HTTPD Mutator function
*
* @param string sets the current httpd picture path to a new location
*/
function setPicturePathHTTPD($name) {
$this->_picture_path_httpd = $name;
}

/**
* Picture path HTTPD Mutator function
*
* @returns the current picture path
*/
function getPicturePathHTTPD() {
return $this->_picture_path_httpd;
}

/**
* Tries to match the LaTeX Formula given as argument against the
* formula cache. If the picture has not been rendered before, it'll
* try to render the formula and drop it in the picture cache directory.
*
* @param string formula in LaTeX format
* @returns the webserver based URL to a picture which contains the
* requested LaTeX formula. If anything fails, the resultvalue is false.
*/
function getFormulaURL($latex_formula) {
// circumvent certain security functions of web-software which
// is pretty pointless right here

$latex_formula = preg_replace("/>/i", ">", $latex_formula);
$latex_formula = preg_replace("/</i", "<", $latex_formula);

$formula_hash = md5($latex_formula);

$filename = 'math-' . $formula_hash.".".$this->_image_format;
$full_path_filename = $this->getPicturePath()."/".$filename;

if (is_file($full_path_filename)) {
return $this->getPicturePathHTTPD()."/".$filename;
} else {
// security filter: reject too long formulas
if (strlen($latex_formula) > $this->_string_length_limit) {
$this->_errorcode = 1;
return false;
}

// security filter: try to match against LaTeX-Tags Blacklist
for ($i=0;$i<sizeof($this->_latex_tags_blacklist);$i++) {
if (stristr($latex_formula,$this->_latex_tags_blacklist[$i])) {
$this->_errorcode = 2;
return false;
}
}

// security checks assume correct formula, let's render it
if ($this->renderLatex($latex_formula)) {
return $this->getPicturePathHTTPD()."/".$filename;
} else {
$this->_errorcode = 3;
return false;
}
}
}

// ====================================================================================
// private functions
// ====================================================================================

/**
* wraps a minimalistic LaTeX document around the formula and returns a string
* containing the whole document as string. Customize if you want other fonts for
* example.
*
* @param string formula in LaTeX format
* @returns minimalistic LaTeX document containing the given formula
*/
function wrap_formula($latex_formula) {
# $string = "\documentclass[".$this->_font_size."pt]{".$this->_latexclass."}\n";
# $string .= "\usepackage[latin1]{inputenc}\n";
$string = "\documentclass{".$this->_latexclass."}\n";
$string .= "\usepackage{amsmath}\n";
$string .= "\usepackage{amsfonts}\n";
$string .= "\usepackage{amssymb}\n";
$string .= "\pagestyle{empty}\n";
$string .= "\begin{document}\n";
$string .= "$".$latex_formula."$\n";
$string .= "\end{document}\n";

return $string;
}

/**
* returns the dimensions of a picture file using 'identify' of the
* imagemagick tools. The resulting array can be adressed with either
* $dim[0] / $dim[1] or $dim["x"] / $dim["y"]
*
* @param string path to a picture
* @returns array containing the picture dimensions
*/
function getDimensions($filename) {
$output=exec($this->_identify_path." ".$filename);
$result=explode(" ",$output);
$dim=explode("x",$result[2]);
$dim["x"] = $dim[0];
$dim["y"] = $dim[1];

return $dim;
}

/**
* Renders a LaTeX formula by the using the following method:
* - write the formula into a wrapped tex-file in a temporary directory
* and change to it
* - Create a DVI file using latex (tetex)
* - Convert DVI file to Postscript (PS) using dvips (tetex)
* - convert, trim and add transparancy by using 'convert' from the
* imagemagick package.
* - Save the resulting image to the picture cache directory using an
* md5 hash as filename. Already rendered formulas can be found directly
* this way.
*
* @param string LaTeX formula
* @returns true if the picture has been successfully saved to the picture
* cache directory
*/
function renderLatex($latex_formula) {
$latex_document = $this->wrap_formula($latex_formula);

$current_dir = getcwd();

chdir($this->_tmp_dir);

// create temporary latex file
$fp = fopen($this->_tmp_dir."/".$this->_tmp_filename.".tex","a+");
fputs($fp,$latex_document);
fclose($fp);

// create temporary dvi file
$command = $this->_latex_path." --interaction=nonstopmode ".$this->_tmp_filename.".tex";
$status_code = exec($command);

if (!$status_code) {
$this->cleanTemporaryDirectory();
chdir($current_dir);
$this->_errorcode = 4;
return false;
}

// convert dvi file to postscript using dvips
$command = $this->_dvips_path." -q -E ".$this->_tmp_filename.".dvi"." -o ".$this->_tmp_filename.".ps";
$status_code = exec($command);

// imagemagick convert ps to image and trim picture
$command = $this->_convert_path." -density ".$this->_formula_density.
" -trim -transparent \"#FFFFFF\" ".$this->_tmp_filename.".ps ".
$this->_tmp_filename.".".$this->_image_format;

$status_code = exec($command);

// test picture for correct dimensions
$dim = $this->getDimensions($this->_tmp_filename.".".$this->_image_format);

if ( ($dim["x"] > $this->_xsize_limit) or ($dim["y"] > $this->_ysize_limit)) {
$this->cleanTemporaryDirectory();
chdir($current_dir);
$this->_errorcode = 5;
$this->_errorextra = ": " . $dim["x"] . "x" . number_format($dim["y"],0,"","");
return false;
}

// copy temporary formula file to cahed formula directory
$latex_hash = md5($latex_formula);
$filename = $this->getPicturePath()."/math-".$latex_hash.".".$this->_image_format;

$status_code = copy($this->_tmp_filename.".".$this->_image_format,$filename);

$this->cleanTemporaryDirectory();

if (!$status_code) {
chdir($current_dir);
$this->_errorcode = 6;
return false;
}
chdir($current_dir);

return true;
}

/**
* Cleans the temporary directory
*/
function cleanTemporaryDirectory() {

$current_dir = getcwd();
chdir($this->_tmp_dir);

unlink($this->_tmp_dir."/".$this->_tmp_filename.".tex");
unlink($this->_tmp_dir."/".$this->_tmp_filename.".aux");
unlink($this->_tmp_dir."/".$this->_tmp_filename.".log");
unlink($this->_tmp_dir."/".$this->_tmp_filename.".dvi");
unlink($this->_tmp_dir."/".$this->_tmp_filename.".ps");
unlink($this->_tmp_dir."/".$this->_tmp_filename.".".$this->_image_format);

chdir($current_dir);
}

}

/**
* LaTeX Rendering Class - Calling function
* Copyright (C) 2003 Benjamin Zeiss <zeiss@math.uni-goettingen.de>
*
* This library is free software; you can redistribute it and/or
* modify it under the terms of the GNU Lesser General Public
* License as published by the Free Software Foundation; either
* version 2.1 of the License, or (at your option) any later version.
*
* This library is distributed in the hope that it will be useful,
* but WITHOUT ANY WARRANTY; without even the implied warranty of
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
* Lesser General Public License for more details.
*
* You should have received a copy of the GNU Lesser General Public
* License along with this library; if not, write to the Free Software
* Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA
* --------------------------------------------------------------------
* @author Benjamin Zeiss <zeiss@math.uni-goettingen.de>
* @version v0.8
* @package latexrender
* Revised by Steve Mayer
* This file can be included in many PHP programs by using something like (see example.php to see how it can be used)
* include_once('/full_path_here_to/latexrender/latex.php');
* $text_to_be_converted=latex_content($text_to_be_converted);
* $text_to_be_converted will then contain the link to the appropriate image
* or an error code as follows (the 500 values can be altered in class.latexrender.php):
* 0 OK
* 1 Formula longer than 500 characters
* 2 Includes a blacklisted tag
* 3 (Not used) Latex rendering failed
* 4 Cannot create DVI file
* 5 Picture larger than 500 x 500 followed by x x y dimensions
* 6 Cannot copy image to pictures directory
*/

function renderMath($latex_formula) {

global $wgMathDirectory, $wgMathPath, $wgTmpDirectory,
$wgLaTexCommand,
$wgDvipsCommand,
$wgImageMagickConvertCommand,
$wgImageMagickIdentifyCommand;

$latex_formula = '\displaystyle ' . $latex_formula;
$latex = new LatexRender( $wgMathDirectory,
$wgMathPath,
$wgTmpDirectory);

#check Math dir
if(!file_exists($wgMathDirectory)) @mkdir($wgMathDirectory);
if(!file_exists($wgTmpDirectory)) @mkdir($wgTmpDirectory);

$latex->_latex_path = $wgLaTexCommand;
$latex->_dvips_path = $wgDvipsCommand;
$latex->_convert_path = $wgImageMagickConvertCommand;
$latex->_identify_path = $wgImageMagickIdentifyCommand;

$url = $latex->getFormulaURL($latex_formula);

$alt_latex_formula = htmlentities($latex_formula, ENT_QUOTES);
$alt_latex_formula = str_replace("\r","",$alt_latex_formula);
$alt_latex_formula = str_replace("\n","
",$alt_latex_formula);
$alt_latex_formula = str_replace('\displaystyle ','',$alt_latex_formula);

if ($url != false) {
$text = "<img src='$url' title='$alt_latex_formula' alt='$alt_latex_formula' class=tex>";
} else {
$text = "[Unparseable or potentially dangerous latex formula. Error $latex->_errorcode $latex->_errorextra]";
}

return $text;
}

?>
</nowiki>
</pre>

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