具体内容如下

load->helper(array('form', 'url'));
  }
 
  /**
   * 首页
   */
  public function index() {
    $this->load->view('upload_form', array('error' => ' ' ));
  }
   
   
  public function do_upload()
  {
    $config['upload_path']   = './data/uploads/';
    $config['allowed_types']  = 'gif|jpg|png';
    $config['max_size']   = 100;
    $config['max_width']    = 1024;
    $config['max_height']    = 768;
 
    $this->load->library('upload', $config);
 
    if ( ! $this->upload->do_upload('userfile'))
    {
      $error = array('error' => $this->upload->display_errors());
 
      $this->load->view('upload_form', $error);
    }
    else
    {
      $data = array('upload_data' => $this->upload->data());
       
      $this->load->library('image_lib');      
      list($width, $height) = getimagesize($data['upload_data']['full_path']);
      $config['image_library'] = 'gd2';
      $config['source_image'] = $data['upload_data']['full_path'];
      $config['maintain_ratio'] = TRUE;
      if($width >= $height)
      {
        $config['master_dim'] = 'height';
      }else{
        $config['master_dim'] = 'width';
      }
      $config['width'] = 180;
      $config['height'] = 180;
      $this->image_lib->initialize($config);
      $this->image_lib->resize();
     
      $config['maintain_ratio'] = FALSE;
      if($width >= $height)
      {
        $config['x_axis'] = floor(($width * 180 / $height - 180)/2);
      }else{
        $config['y_axis'] = floor(($height * 180 / $width - 180)/2);
      }
      $this->image_lib->initialize($config);
      $this->image_lib->crop();
       
      $this->load->view('upload_success', $data);
    }
  }
}