Change Upload Path

Hi, is there any hook/filter to change the uploaded files to another directory except those are initiated in settings page?
By now, I manually added this code to core file of this plugin.

//if {user_login} keyword used, replace with current user login : Actually used in setting page as /uploads/{user_login}/
	if (strpos($file_dir,'{user_login}') !== false) {
		global $current_user;
      		get_currentuserinfo();
      		$user_login = $current_user->user_login;

		if(isset($_POST['user_login'])) {
			$entry_user_login = $_POST['user_login'];
			$file_dir = str_replace("{user_login}",$entry_user_login,$file_dir);
		} else {
			//$user_login = get_current_user_login() ? get_current_user_login() : '0';
			$file_dir = str_replace("{user_login}",$user_login,$file_dir);
		}
	}

is it possible to do without editing core file?

https://wordpress.org/plugins/ajax-upload-for-gravity-forms/