php实现等比例压缩图片

/**
   * desription 压缩图片
   * @param sting $imgsrc 图片路径
   * @param string $imgdst 压缩后保存路径
   */
  public function compressedImage($imgsrc, $imgdst) {
    list($width, $height, $type) = getimagesize($imgsrc);
    
    $new_width = $width;//压缩后的图片宽
    $new_height = $height;//压缩后的图片高
        
    if($width >= 600){
      $per = 600 / $width;//计算比例
      $new_width = $width * $per;
      $new_height = $height * $per;
    }
    
    switch ($type) {
      case 1:
        $giftype = check_gifcartoon($imgsrc);
        if ($giftype) {
          header('Content-Type:image/gif');
          $image_wp = imagecreatetruecolor($new_width, $new_height);
          $image = imagecreatefromgif($imgsrc);
          imagecopyresampled($image_wp, $image, 0, 0, 0, 0, $new_width, $new_height, $width, $height);
          //90代表的是质量、压缩图片容量大小
          imagejpeg($image_wp, $imgdst, 90);
          imagedestroy($image_wp);
          imagedestroy($image);
        }
        break;
      case 2:
        header('Content-Type:image/jpeg');
        $image_wp = imagecreatetruecolor($new_width, $new_height);
        $image = imagecreatefromjpeg($imgsrc);
        imagecopyresampled($image_wp, $image, 0, 0, 0, 0, $new_width, $new_height, $width, $height);
        //90代表的是质量、压缩图片容量大小
        imagejpeg($image_wp, $imgdst, 90);
        imagedestroy($image_wp);
        imagedestroy($image);
        break;
      case 3:
        header('Content-Type:image/png');
        $image_wp = imagecreatetruecolor($new_width, $new_height);
        $image = imagecreatefrompng($imgsrc);
        imagecopyresampled($image_wp, $image, 0, 0, 0, 0, $new_width, $new_height, $width, $height);
        //90代表的是质量、压缩图片容量大小
        imagejpeg($image_wp, $imgdst, 90);
        imagedestroy($image_wp);
        imagedestroy($image);
        break;
    }
  }