php高清晰度无损图片压缩功能的实现代码

 compressImg($dst_img);

 src = $src;
     $this->percent = $percent;
   }
   /** 高清压缩图片
    * @param string $saveName 提供图片名（可不带扩展名，用源图扩展名）用于保存。或不提供文件名直接显示
    */
   public function compressImg($saveName='')
   {
     $this->_openImage();
     if(!empty($saveName)) $this->_saveImage($saveName); //保存
     else $this->_showImage();
   }
   /**
    * 内部：打开图片
    */
   private function _openImage()
   {
     list($width, $height, $type, $attr) = getimagesize($this->src);
     $this->imageinfo = array(
       'width'=>$width,
       'height'=>$height,
       'type'=>image_type_to_extension($type,false),
       'attr'=>$attr
     );
     $fun = "imagecreatefrom".$this->imageinfo['type'];
     $this->image = $fun($this->src);
     $this->_thumpImage();
   }
   /**
    * 内部：操作图片
    */
   private function _thumpImage()
   {
     $new_width'] * $this->percent;
     $new_height'] * $this->percent;
     $image_thump = imagecreatetruecolor($new_width,$new_height);
     //将原图复制带图片载体上面，并且按照一定比例压缩,极大的保持了清晰度
     imagecopyresampled($image_thump,$this->image,,,,,$new_width,$new_height,$this->imageinfo['width'],$this->imageinfo['height']);
     imagedestroy($this->image);
     $this->image = $image_thump;
   }
   /**
    * 输出图片:保存图片则用saveImage()
    */
   private function _showImage()
   {
     header('Content-Type: image/'.$this->imageinfo['type']);
     $funcs = "image".$this->imageinfo['type'];
     $funcs($this->image);
   }
   /**
    * 保存图片到硬盘：
    * @param string $dstImgName 、可指定字符串不带后缀的名称，使用源图扩展名 。、直接指定目标图片名带扩展名。
    */
   private function _saveImage($dstImgName)
   {
     if(empty($dstImgName)) return false;
     $allowImgs = ['.jpg', '.jpeg', '.png', '.bmp', '.wbmp','.gif'];  //如果目标图片名有后缀就用目标图片扩展名 后缀，如果没有，则用源图的扩展名
     $dstExt = strrchr($dstImgName ,".");
     $sourseExt = strrchr($this->src ,".");
     if(!empty($dstExt)) $dstExt =strtolower($dstExt);
     if(!empty($sourseExt)) $sourseExt =strtolower($sourseExt);
     //有指定目标名扩展名
     if(!empty($dstExt) && in_array($dstExt,$allowImgs)){
       $dstName = $dstImgName;
     }elseif(!empty($sourseExt) && in_array($sourseExt,$allowImgs)){
       $dstName = $dstImgName.$sourseExt;
     }else{
       $dstName = $dstImgName.$this->imageinfo['type'];
     }
     $funcs = "image".$this->imageinfo['type'];
     $funcs($this->image,$dstName);
   }
   /**
   * 销毁图片
   */
   public function __destruct(){
     imagedestroy($this->image);
   }
 }