codeigniter 图片上传、剪切

<?php
defined('BASEPATH') OR exit('No direct script access allowed');

class Index extends MY_Controller {
	function __construct(){
        parent::__construct();
        $this->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);
        }
    }
}