Using Navigation Bar Tab Events from Widgets

import 'package:flutter/material.dart';
 
class NotificationsScreen extends StatelessWidget {
  const NotificationsScreen({super.key, required this.onTap});
 
  final Function(int) onTap;
 
  @override
  Widget build(BuildContext context) {
    return Center(
      child: IconButton(
          onPressed: () {
            onTap(1);
          },
          icon: const Icon(Icons.search, size: 100),
          iconSize: 100),
    );
  }
}

import 'package:flutter/material.dart';
import 'package:navigationbar_example/view/tabs/home_screen.dart';
import 'package:navigationbar_example/view/tabs/notifications_screen.dart';
import 'package:navigationbar_example/view/tabs/profile_screen.dart';
import 'package:navigationbar_example/view/tabs/search_screen.dart';
 
class MainPage extends StatefulWidget {
  const MainPage({super.key});
 
  @override
  MainPageState createState() => MainPageState();
}
 
class MainPageState extends State<MainPage> {
  int _currentIndex = 0; // 현재 선택된 탭의 인덱스
 
  final List<GlobalKey<NavigatorState>> _navigatorKeys = [
    GlobalKey<NavigatorState>(),
    GlobalKey<NavigatorState>(),
    GlobalKey<NavigatorState>(),
    GlobalKey<NavigatorState>(),
  ];
 
  void _onTap(int index) {
    if (index == _currentIndex) {
      _navigatorKeys[index].currentState?.popUntil((route) => route.isFirst);
    } else {
      setState(() {
        _currentIndex = index;
      });
    }
  }
 
  // 각 탭에서 보여줄 화면 리스트(비워져 있음)
  final List<Widget> _pages = [];
 
  @override // 각 탭에 보여줄 화면을 생성(onTap 함수를 전달)
  void initState() {
    super.initState();
    _pages.addAll([
      const HomeScreen(),
      const SearchScreen(),
      NotificationsScreen(onTap: _onTap),
      ProfileScreen(),
    ]);
  }
 
  @override
  Widget build(BuildContext context) {
    return Scaffold(
      body: IndexedStack(
        index: _currentIndex,
        children: List.generate(_pages.length, (index) {
          return Navigator(
            key: _navigatorKeys[index],
            onGenerateRoute: (routeSettings) {
              return MaterialPageRoute(
                builder: (context) => _pages[index],
              );
            },
          );
        }),
      ), // 선택된 탭의 화면을 보여줄 위젯
      bottomNavigationBar: BottomNavigationBar(
        currentIndex: _currentIndex, // 선택된 탭 인덱스
        onTap: _onTap, // 탭 선택 시 호출할 함수
        items: const [
          BottomNavigationBarItem(
            icon: Icon(Icons.home),
            label: 'Home',
          ),
          BottomNavigationBarItem(
            icon: Icon(Icons.search),
            label: 'Search',
          ),
          BottomNavigationBarItem(
            icon: Icon(Icons.notifications),
            label: 'Notifications',
          ),
          BottomNavigationBarItem(
            icon: Icon(Icons.person),
            label: 'Profile',
          ),
        ],
        selectedItemColor: Colors.blue, // 선택된 아이템 색상
        unselectedItemColor: Colors.grey, // 선택되지 않은 아이템 색상
      ),
    );
  }
}