php图片自动裁剪工具，解决图片变形问题，缩略图问题

<?php    class ImageCut {            public $path = '';            public $key = '';            public function __construct() {                            }            public function set_image($path) {                $this->path = $path;            }            public function header_image(){                header('Content-type:image/jpeg');            }                        public function header_304(){                //304缓存                $this->key = $etag = md5_file($this->path);                $last_mod = filemtime($this->path);                header('ETag:'.$etag);                header('Last-Modified:'.gmdate('D, d M Y H:i:s', $last_mod) . ' GMT');                if ((isset($_SERVER['HTTP_IF_MODIFIED_SINCE']) && strtotime($_SERVER['HTTP_IF_MODIFIED_SINCE']) >= $last_mod)                    || (isset($_SERVER['HTTP_IF_UNMODIFIED_SINCE']) && strtotime($_SERVER['HTTP_IF_UNMODIFIED_SINCE']) < $last_mod)                    || (isset($_SERVER['HTTP_IF_NONE_MATCH']) && $_SERVER['HTTP_IF_NONE_MATCH'] == $etag)) {                    header("HTTP/1.1 304 Not Modified");                    return true;                } else {                    return false;                }            }            public function get_data($width,$height){                if($this->path) {                    $path = $this->path;                } else {                    trigger_error('unset path');                }                if(!file_exists($path)) {                    trigger_error('file not exist');                }                                $img_type = exif_imagetype($path);                $old_size = getimagesize($path);                $old_width = $old_size[0];                $old_height =  $old_size[1];                                if($width==0 && $height==0) {                    $width = $old_width;                    $height = $old_height;                } else if($width==0) {                    if($height>$old_height) {                        $height = $old_height;                    }                    $width = $height/$old_height * $old_width;                } else if($height==0) {                    if($width>$old_width) {                        $width = $old_width;                    }                    $height = $width/$old_width * $old_height;                }                                $dst_wh = $width/$height;                if($old_height>($old_width/$dst_wh)) {                    $src_width = $old_width;                    $src_height = $old_width/$dst_wh;                    $src_x = 0;                    $src_y = ($old_height-$src_height)/2;                } else {                    $src_height = $old_height;                    $src_width = $old_height*$dst_wh;                    $src_y = 0;                    $src_x = ($old_width-$src_width)/2;                }                                                switch($img_type) {                    case IMAGETYPE_JPEG:                        $img = imagecreatefromjpeg($path);                        break;                    case IMAGETYPE_PNG:                        $img = imagecreatefrompng($path);                        break;                    case IMAGETYPE_GIF:                        $img = imagecreatefromgif($path);                        break;                }                                if($src_width<$width) {                    $width = $src_width;                }                if($src_height<$height) {                    $height = $src_height;                }                //重新画                $newimage = imagecreatetruecolor($width,$height);                imagecopyresampled($newimage,$img,0,0,$src_x,$src_y,$width,$height,$src_width,$src_height);                //开始缓存图片                        ob_start();                imagejpeg($newimage,false,90);                $data = ob_get_contents();                ob_end_clean();                imagedestroy($img);                 imagedestroy($newimage);                return $data;            }            public function show($width,$height){                $this->header_image();                $if_304 = $this->header_304();                if($if_304) {                    return;                }                echo $this->get_data($width, $height);            }        }        $cut = new ImageCut();        $cut->set_image('1.jpg');//path可以通过参数传过来        $cut->show(200,200);//随意设置宽高，可以通过参数传过来，?>