php实现图片的操作，也就是裁切，跟加水印

<?

class image {

        protected $img;    

        protected $types = array(

                        1 => 'gif',

                        2 => 'jpg',

                        3 => 'png',

                        6 => 'bmp'

                    );

        public function __construct($img=''){

                !$img && $this->param($img);

        }

        public function param($img){

                $this->img = $img;

                return $this;

        }

        public function getImageInfo($img){

                $info = @getimagesize($img);

                if(isset($this->types[$info[2]])){

                        $info['ext'] = $info['type'] = $this->types[$info[2]];

                } else{

                        $info['ext'] = $info['type'] = 'jpg';

                }

                $info['type'] == 'jpg' && $info['type'] = 'jpeg';

                $info['size'] = @filesize($img);

                return $info;

        }

        public function thumb($filename,$new_w=160,$new_h=120,$cut=0,$big=0){

        $info  = $this->getImageInfo($this->img);

        if(!empty($info[0])) {

            $old_w  = $info[0];

            $old_h  = $info[1];

            $type   = $info['type'];

            $ext    = $info['ext'];