代码

    /*
  * $filename 图片地址
  * $src 替换地址
  * $degrees 转换度数
  */ 
    private function flip($filename='',$src='',$degrees = 90)
    {
        if(!$filename || !file_exists($filename) || !$src || !file_exists($src)){
            return false;
        }
        $data = @getimagesize($filename);
        if($data==false)return false;
        //读取旧图片 
        switch ($data[2]) {
            case 1:
                $src_f = imagecreatefromgif($filename);break;
            case 2:
                $src_f = imagecreatefromjpeg($filename);break;
            case 3:
                $src_f = imagecreatefrompng($filename);break;
        }
        if($src_f=="")return false;
        $rotate = @imagerotate($src_f, $degrees,0);
        if(!imagejpeg($rotate,$src,100))return false;
        @imagedestroy($rotate);
        return true;
    }