public function getDimensions()
{
// Check if we know it already
if ($this->_width == 0 && $this->_height == 0) {
$tmp = $this->toFile();
$details = @getimagesize($tmp);
list($this->_width, $this->_height) = $details;
unlink($tmp);
}
return array('width' => $this->_width, 'height' => $this->_height);
}