问不带maintain_ration的CodeIgniter crop()

EN

 function do_crop() {

    $config = array(
   'image_library' => 'gd2',
   'source_image' => realpath(APPPATH . '../upload_img/solg6.jpg'), 
   'new_image' => $this->gallery_path_url . 'thumbaaa.jpg',
   'maintain_ration' => false, 
   'width' => 150,
   'height' => 150,
     'x_axis' => 20,
   'y_axis' => 20
  );

  $this->load->library('image_lib');
  $this->image_lib->initialize($config);
  if ( ! $this->image_lib->crop())
  {
      echo $this->image_lib->display_errors();
  }
  $this->image_lib->clear();
 }