/**
* Add filter to current image
*
* @param string|callable $filter
* @return $this
*
* @throws Exception
*/
public function addFilter($filter)
{
$args = func_get_args();
$args[0] = $this->_image;
$newImage = null;
if (is_string($filter)) {
$filterClass = __NAMESPACE__ . '\\Filter';
if (method_exists($filterClass, $filter)) {
$newImage = call_user_func_array(array($filterClass, $filter), $args);
} else {
throw new Exception('Undefined Image Filter: ' . $filter);
}
} elseif (is_callable($filter)) {
$newImage = call_user_func_array($filter, $args);
}
if (Helper::isGdRes($newImage)) {
$this->_replaceImage($newImage);
}
return $this;
}