商品缩略图实现

<?php// 验证码类class image {    protected $im;    protected $img_width;    protected $img_height;    protected $img_type;    static public function make_thumb($ori,$w=200,$h=200) {        // 判断原图大小,如果原图比缩略还小,不必处理.        // 读出大图当画布        $info = self::getinfo($ori);        if($info['func'] === false) {            return false;        }        $createfunc = 'imagecreatefrom' . $info['func']; // 分析出读取大图所用的函数名.        $src = $createfunc($ori);        // 创建小画布,并把背景做成灰色        $small = imagecreatetruecolor($w,$h);        $gray = imagecolorallocate($small,255,255,255);        imagefill($small,0,0,$gray);        // 复制大图到小图        $scale = min($w/$info['width'], $h/$info['height']); // 以更小的缩小比例为准,才能装下        // 根据比例,算最终复制过去的块的大小.        $realw = $info['width'] * $scale;        $realh = $info['height'] * $scale;        // 生成小图        /*        bool imagecopyresampled ( resource $dst_image , resource $src_image , int $dst_x , int $dst_y , int $src_x , int $src_y , int $dst_w , int $dst_h , int $src_w , int $src_h )        */        // 计算留白        $lw = round(($w - $realw)/2); // 计算左侧留的宽度        $lh = round(($h - $realh)/2); // 计算上部留的高度        imagecopyresampled($small,$src,$lw,$lh,0,0,$realw,$realh,$info['width'],$info['height']);               // 计算小图片的存储路径$pic = str_replace(ROOT,'',$ori);;        $thumburl = str_replace('.','_thumb.',$pic);$thumburl = ROOT . $thumburl;        $imagefunc = 'image' . $info['func'];        if($imagefunc($small,$thumburl)) {            return str_replace(ROOT,'',$thumburl);        } else {            return false;        }    }    static public function getinfo($ori) {        $arr = getimagesize($ori);        // 如果原始图片分析不出来,直接false        if($arr === false) {            return false;        }                $info = array();                $info['width'] = $arr[0];        $info['height'] = $arr[1];                switch($arr[2]) {            case 1:            $info['func'] = 'gif';            break;            case 2:            $info['func'] = 'jpeg';            break;            case 3:            $info['func'] = 'png';            break;            case 6:            $info['func'] = 'wbmp';            break;            default:            $info['func'] = false;                }        return $info;    }}?>