导航问题（底部导航栏）

Question

我在整个应用程序中都有持久的底部导航栏（登录页面除外）。看起来像：

    Widget build(BuildContext context) {
return Scaffold(
  body: IndexedStack(
      index: _currentIndex,
      children: <Widget>[
        Navigator(
            key:_userScreen,
            onGenerateRoute: (route) => MaterialPageRoute(
              settings: route,
              builder: (context) => UserPage(userId: 
                       widget.userId),
            ),
          ),
        ),
        Navigator(
          key: _searchScreen,
          onGenerateRoute: (route) => MaterialPageRoute(
            settings: route,
            builder: (context) => SearchPage(userId: 
            widget.userId),
          ),
        ),
        Navigator(
          key:_optionsScreen,
          onGenerateRoute: (route) => MaterialPageRoute(
            settings: route,
            builder: (context) => OptionsPage(userId: 
            widget.userId),
          ),
        ),
      ]
  ),
   bottomNavigationBar: BottomNavigationBar(
    type: BottomNavigationBarType.fixed,
    selectedFontSize: 12.0,
    unselectedFontSize: 12.0,
    currentIndex: _currentIndex,
    onTap: (val) => _onTap(val, context),
    backgroundColor: Colors.blue[50],
    items: [
      BottomNavigationBarItem(
        icon: Icon(LineIcons.graduation_cap),
        title: Text('Courses'),
      ),
      BottomNavigationBarItem(
        icon: Icon(LineIcons.search),
        title: Text('Search'),
      ),
      BottomNavigationBarItem(
        icon: Icon(LineIcons.user),
        title: Text('Options'),
      ),
    ],
  ),
);

}

现在，我想删除页面之一上的底部导航栏（用于打开视频播放器）。我该怎么做？ 我试图在我的应用程序主目录中建立到videoPage的单独路由，并使用Navigator.pushNamed转到那里，但由于我位于另一个导航器中，因此转到该导航器的根目录...。