/
Tex2png.php
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/
Tex2png.php
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<?php
namespace Gregwar\Tex2png;
use Gregwar\Cache\Cache;
/**
* Helper to generate PNG from LaTeX formula
*
* @author Grégoire Passault <g.passault@gmail.com>
*/
class Tex2png
{
/**
* Where is the LaTex ?
*/
const LATEX = "/usr/bin/latex";
/**
* Where is the DVIPNG ?
*/
const DVIPNG = "/usr/bin/dvipng";
/**
* LaTeX packges
*/
public $packages = array('amssymb,amsmath', 'color', 'amsfonts', 'amssymb', 'pst-plot');
/**
* Cache directory
*/
public $cacheDir = 'cache/tex';
/**
* Actual cache directory
*/
public $actualCacheDir = null;
/**
* Temporary directory
* This is needed to write temporary files needed for
* generation
*/
public $tmpDir = '/tmp';
/**
* Target file
*/
public $file = null;
/**
* Cache
*/
public $cache = null;
/**
* Target actual file
*/
public $actualFile = null;
/**
* Hash
*/
public $hash;
/**
* LaTeX formula
*/
public $formula;
/**
* Target density
*/
public $density;
/**
* Error (if any)
*/
public $error = null;
public static function create($formula, $density = 155)
{
return new self($formula, $density);
}
public function __construct($formula, $density = 155)
{
$datas = array(
'formula' => $formula,
'density' => $density,
);
$this->formula = $formula;
$this->density = $density;
$this->hash = sha1(serialize($datas));
$this->cache = new Cache;
return $this;
}
/**
* Sets the target directory
*/
public function saveTo($file)
{
$this->actualFile = $this->file = $file;
return $this;
}
/**
* Generates the image
*/
public function generate()
{
$tex2png = $this;
$generate = function($target) use ($tex2png) {
$tex2png->actualFile = $target;
try {
// Generates the LaTeX file
$tex2png->createFile();
// Compile the latexFile
$tex2png->latexFile();
// Converts the DVI file to PNG
$tex2png->dvi2png();
} catch (\Exception $e) {
$tex2png->error = $e;
}
$tex2png->clean();
};
if ($this->actualFile === null) {
$target = $this->hash . '.png';
$this->cache->getOrCreate($target, array(), $generate);
$this->file = $this->cache->getCacheFile($target);
$this->actualFile = $this->cache->getCacheFile($target, true);
} else {
$generate($this->actualFile);
}
return $this;
}
/**
* Create the LaTeX file
*/
public function createFile()
{
$tmpfile = $this->tmpDir . '/' . $this->hash . '.tex';
$tex = '\documentclass[12pt]{article}'."\n";
$tex .= '\usepackage[utf8]{inputenc}'."\n";
// Packages
foreach ($this->packages as $package) {
$tex .= '\usepackage{' . $package . "}\n";
}
$tex .= '\begin{document}'."\n";
$tex .= '\pagestyle{empty}'."\n";
$tex .= '\begin{displaymath}'."\n";
$tex .= $this->formula."\n";
$tex .= '\end{displaymath}'."\n";
$tex .= '\end{document}'."\n";
if (file_put_contents($tmpfile, $tex) === false) {
throw new \Exception('Failed to open target file');
}
}
/**
* Compiles the LaTeX to DVI
*/
public function latexFile()
{
$command = 'cd ' . $this->tmpDir . '; ' . static::LATEX . ' ' . $this->hash . '.tex < /dev/null |grep ^!|grep -v Emergency > ' . $this->tmpDir . '/' .$this->hash . '.err 2> /dev/null 2>&1';
shell_exec($command);
if (!file_exists($this->tmpDir . '/' . $this->hash . '.dvi')) {
throw new \Exception('Unable to compile LaTeX formula (is latex installed? check syntax)');
}
}
/**
* Converts the DVI file to PNG
*/
public function dvi2png()
{
// XXX background: -bg 'rgb 0.5 0.5 0.5'
$command = static::DVIPNG . ' -q -T tight -D ' . $this->density . ' -o ' . $this->actualFile . ' ' . $this->tmpDir . '/' . $this->hash . '.dvi 2>&1';
if (shell_exec($command) === null) {
throw new \Exception('Unable to convert the DVI file to PNG (is dvipng installed?)');
}
}
/**
* Cleaning
*/
public function clean()
{
@shell_exec('rm -f ' . $this->tmpDir . '/' . $this->hash . '.* 2>&1');
}
/**
* Gets the HTML code for the image
*/
public function html()
{
if ($this->error)
{
return '<span style="color:red">LaTeX: syntax error (' . $this->error->getMessage() . ')</span>';
}
else
{
return '<img class="formula" title="Formula" src="' . $this->getFile() . '">';
}
}
/**
* Sets the cache directory
*/
public function setCacheDirectory($directory)
{
$this->cache->setCacheDirectory($directory);
}
/**
* Sets the actual cache directory
*/
public function setActualCacheDirectory($actualDirectory)
{
$this->cache->setActualCacheDirectory($actualDirectory);
}
/**
* Sets the temporary directory
*/
public function setTempDirectory($directory)
{
$this->tmpDir = $directory;
}
/**
* Returns the PNG file
*/
public function getFile()
{
return $this->hookFile($this->file);
}
/**
* Hook that helps extending this class (eg: adding a prefix or suffix)
*/
public function hookFile($filename)
{
return $filename;
}
/**
* The string representation is the cache file
*/
public function __toString()
{
return $this->getFile();
}
}