public function format($format)
{
switch ($format) {
case 'png':
$this->writer->setRenderer(new Png());
break;
case 'eps':
$this->writer->setRenderer(new Eps());
break;
case 'svg':
$this->writer->setRenderer(new Svg());
break;
default:
throw new \InvalidArgumentException('Invalid format provided.');
}
return $this;
}