namespace common\components;

 class ResizeImageHelper

 {

     public $type;//图片类型

     public $width;//实际宽度

     public $height;//实际高度

     public $resize_width;//改变后的宽度

     public $resize_height;//改变后的高度

     public $cut;//是否裁图

     public $srcimg;//源图象

     public $dstimg;//目标图象地址

     public $im;//临时创建的图象

     public $quality;//图片质量

     public $img_array = array('jpg', 'png', 'gif');

     /**

      * 生成保持原图纵横比的缩略图，支持.png .jpg .gif

      * 缩略图类型统一为.png格式

      * $img     原图像文件名称

      * $wid     缩略图宽

      * $hei     缩略图高

      * $c       是否剪裁

      * $dstpath 缩略图文件名称，为空覆盖原图像文件

      * $quality 质量最大100

      * @return bool

      */

     public  function createThumbnail($img, $wid, $hei, $c, $dstpath, $quality = 100)

     {

         $this->srcimg = $img;

         $this->resize_width = $wid;

         $this->resize_height = $hei;

         $this->cut = $c;

         $this->quality = $quality;

         //$this->type=strtolower(substr(strrchr($this->srcimg,'.'),1));//图片的类型

         $this->type = $this->checkFileType($this->srcimg);//更为严格的检测图片类型

         if (!in_array($this->type, $this->img_array)) {

             return '';

         }

         $this->initi_img();//初始化图象

         $this->dst_img($dstpath);//目标图象地址

         $this->width = imagesx($this->im);

         $this->height = imagesy($this->im);

         $this->newimg();//生成图象

         ImageDestroy($this->im);

         return true;

     }

     private  function newimg()

     {

         $resize_ratio = ($this->resize_width) / ($this->resize_height);//改变后的图象的比例

         $ratio = ($this->width) / ($this->height);//实际图象的比例

         if (($this->cut) == '1') {//裁图

             if (function_exists('imagepng') && (str_replace('.', '', PHP_VERSION) >= 512)) {//针对php版本大于5.12参数变化后的处理情况

                 $quality = 9;

             }

             if ($ratio >= $resize_ratio) {//高度优先

                 $newimg = imagecreatetruecolor($this->resize_width, $this->resize_height);

                 imagecopyresampled($newimg, $this->im, 0, 0, 0, 0, $this->resize_width, $this->resize_height, (($this->height) * $resize_ratio), $this->height);

                 imagejpeg($newimg, $this->dstimg, $this->quality);

             }

             if ($ratio < $resize_ratio) {//宽度优先

                 $newimg = imagecreatetruecolor($this->resize_width, $this->resize_height);

                 imagecopyresampled($newimg, $this->im, 0, 0, 0, 0, $this->resize_width, $this->resize_height, $this->width, (($this->width) / $resize_ratio));

                 imagejpeg($newimg, $this->dstimg, $this->quality);

             }

         } else {//不裁图

             if ($ratio >= $resize_ratio) {

                 $newimg = imagecreatetruecolor($this->resize_width, ($this->resize_width) / $ratio);

                 imagecopyresampled($newimg, $this->im, 0, 0, 0, 0, $this->resize_width, ($this->resize_width) / $ratio, $this->width, $this->height);

                 imagejpeg($newimg, $this->dstimg, $this->quality);

             }

             if ($ratio < $resize_ratio) {

                 $newimg = imagecreatetruecolor(($this->resize_height) * $ratio, $this->resize_height);

                 imagecopyresampled($newimg, $this->im, 0, 0, 0, 0, ($this->resize_height) * $ratio, $this->resize_height, $this->width, $this->height);

                 imagejpeg($newimg, $this->dstimg, $this->quality);

             }

         }

     }

     private function initi_img()

     {//初始化图象

         if ($this->type == 'jpg') {

             $this->im = imagecreatefromjpeg($this->srcimg);

         }

         if ($this->type == 'gif') {

             $this->im = imagecreatefromgif($this->srcimg);

         }

         if ($this->type == 'png') {

             $this->im = imagecreatefrompng($this->srcimg);

         }

     }

     private function dst_img($dstpath)

     {//图象目标地址

         $full_length = strlen($this->srcimg);

         $type_length = strlen($this->type);

         $name_length = $full_length - $type_length;

         $name = substr($this->srcimg, 0, $name_length - 1);

         $this->dstimg = $dstpath;

         //echo $this->dstimg;

     }

     //读取文件前几个字节 判断文件类型

     private function checkFileType($filename)

     {

         $file = fopen($filename, 'rb');

         $bin = fread($file, 2); //只读2字节

         fclose($file);

         $strInfo = @unpack("c2chars", $bin);

         $typeCode = intval($strInfo['chars1'] . $strInfo['chars2']);

         switch ($typeCode) {

             case 7790:

                 $fileType = 'exe';

                 break;

             case 7784:

                 $fileType = 'midi';

                 break;

             case 8297:

                 $fileType = 'rar';

                 break;

             case 255216:

                 $fileType = 'jpg';

                 break;

             case 7173:

                 $fileType = 'gif';

                 break;

             case 6677:

                 $fileType = 'bmp';

                 break;

             case 13780:

                 $fileType = 'png';

                 break;

             default:

                 $fileType = 'unknown' . $typeCode;

                 break;

         }

         if ($strInfo['chars1'] == '-1' && $strInfo['chars2'] == '-40') {

             return 'jpg';

         }

         if ($strInfo['chars1'] == '-119' && $strInfo['chars2'] == '80') {

             return 'png';

         }

         return $fileType;

     }

 }

$resizeimage = new ResizeImageHelper();

$resizeimage->CreateThumbnail('path/../1.png', 1440,400, 1, 'path/../2.png', 80);