php图片无损压缩

测试代码

compressImg($dst_img);

压缩的主要代码：imgcompress.class.php

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->imageinfo['width'] * $this->percent;
    $new_height = $this->imageinfo['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,$this->image,0,0,0,0,$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 ,".");
   echo  $sourseExt = strrchr($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);
   Imagejpeg( $this->image,'./img/ceshi'.$sourseExt,50);
  }
  /**
  * 销毁图片
  */
  public function __destruct(){
    imagedestroy($this->image);
  }
}