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;     } }

调用示例

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