public function renderlatexTask()
{
$expression = Request::getVar('expression', '');
$dir = PATH_APP . DS . 'cache' . DS . 'ckeditor' . DS . 'hubzeroequation' . DS;
$filename = uniqid("equation_");
$error = null;
//build tex document
$doc = '\\documentclass[12pt]{article}' . "\n";
$doc .= '\\usepackage[utf8]{inputenc}' . "\n";
$doc .= '\\usepackage{amssymb,amsmath}' . "\n";
$doc .= '\\usepackage{color}' . "\n";
$doc .= '\\usepackage{amsfonts}' . "\n";
$doc .= '\\usepackage{amssymb}' . "\n";
$doc .= '\\usepackage{pst-plot}' . "\n";
$doc .= '\\begin{document}' . "\n";
$doc .= '\\pagestyle{empty}' . "\n";
$doc .= '\\begin{displaymath}' . "\n";
$doc .= $expression . "\n";
$doc .= '\\end{displaymath}' . "\n";
$doc .= '\\end{document}' . "\n";
//if cache doesn't exist, create it
if (!is_dir($dir)) {
\Hubzero\Filesystem::makeDirectory($dir);
}
if (file_put_contents($dir . DS . $filename . '.tex', $doc) === false) {
throw new \Exception('Failed to open target file');
}
try {
//execute latex to build dvi
$command = 'cd ' . $dir . '; /usr/bin/latex ' . $filename . '.tex < /dev/null |grep ^!|grep -v Emergency > ' . $dir . DS . $filename . '.error 2> /dev/null 2>&1';
exec($command, $output_lines, $exit_status);
//execute dvi2png to build png
$command = "/usr/bin/dvipng -bg 'transparent' -q -T tight -D 100 -o " . $dir . DS . $filename . '.png ' . $dir . DS . $filename . '.dvi 2>&1';
exec($command, $output_lines, $exit_status);
if ($exit_status != 0) {
throw new \Exception("dvi2png failed");
}
} catch (\Exception $e) {
$error = $e->getMessage();
}
//build response
$object = new stdClass();
if ($error) {
$object->error = $error;
$object->img = 'data:image/png;base64,';
} else {
//no errors - send base64 encoded image
$object->error = "";
$imgbinary = fread(fopen($dir . DS . $filename . '.png', 'r'), filesize($dir . DS . $filename . '.png'));
$base64img = 'data:image/png;base64,' . base64_encode($imgbinary);
$object->img = $base64img;
}
$object->expression = $expression;
//clean up our cache mess
shell_exec('rm ' . $dir . $filename . '.*');
$this->send($object);
}
