带有 Riverpod 的 Flutter 导航栏

Question

我试图管理我的状态，但我真的做不到。 我想学习如何使用riverpod包在管理页面底部创建一个导航栏。

我设法管理我们单击的页面，但我看不到如何根据所选按钮返回正确的寻呼机

主要飞镖：

import 'package:flutter/material.dart';
import 'package:hooks_riverpod/hooks_riverpod.dart';
import 'package:app/ui/screens/my_app/my_app_screen.dart';

void main() {
  runApp(
    const ProviderScope(child: MyApp()),
  );
}

NavigationBarScreen.dart：

import 'package:flutter/material.dart';
import 'package:flutter_hooks/flutter_hooks.dart';
import 'package:hooks_riverpod/hooks_riverpod.dart';

final provider = StateNotifierProvider((ref) => NavigationNotifier());

class NavigationBarScreen extends HookWidget
{
  @override
  Widget build(BuildContext context) {

    return SafeArea(
      child: Scaffold(
        body : Container(
              margin: EdgeInsets.only(left : 8, right : 8, bottom: 8),
              decoration: BoxDecoration(
                borderRadius: BorderRadius.only(
                    topRight: Radius.circular(20), topLeft: Radius.circular(20)),
                boxShadow: [
                  BoxShadow(color: AppColors.colorShadowLight, spreadRadius: 0, blurRadius: 10),
                ],
              ),
              child: ClipRRect(
                borderRadius: BorderRadius.circular(50.0),
                child: BottomNavigationBar(
                  type: BottomNavigationBarType.fixed,
                  backgroundColor: AppColors.colorBgDark,
                  fixedColor: AppColors.colorContrastOrange,
                  unselectedItemColor: AppColors.colorFontLight2,
                  currentIndex: 0,
                  showSelectedLabels: false,
                  showUnselectedLabels: false,
                  onTap: context.read(provider).selectPage,
                  items: [
                    BottomNavigationBarItem(
                      icon: Icon(Icons.home),
                      title: Text('Home'),
                    ),
                    BottomNavigationBarItem(
                      icon: Icon(Icons.settings),
                      title: Text('Settings'),
                    ),
                  ],
                ),
              ),
            ),
      ),
    );
  }
}

NavigationNotifier.dart：

import 'package:hooks_riverpod/hooks_riverpod.dart';

enum NavigationBarEvent { HOME, PROFIL}

class NavigationNotifier extends StateNotifier<PageModel> {
  NavigationNotifier() : super(defaultPage);

  static const defaultPage = PageModel(NavigationBarEvent.HOME);

  void selectPage(int i){
    switch (i) {
      case 0:
        state = PageModel(NavigationBarEvent.HOME);
        break;
      case 1:
        state = PageModel(NavigationBarEvent.PROFIL);
        break;
    }
  }
}

class PageModel {
  const PageModel(this.page);
  final NavigationBarEvent page;
}

Answer 1

当用户单击底部栏时，您似乎已经实现了修改状态的所有逻辑。

剩下的唯一一点是听取状态（可能在您的 Scaffold 中），并决定显示哪个页面。

一种可能性是写：

class NavigationBarScreen extends HookWidget {
  @override
  Widget build(BuildContext context) {
    final pageModel = useProvider(provider.state);

    Widget body;
    switch (pageModel.page) {
      case NavigationBarEvent.HOME:
        body = Home();
        break;
      case NavigationBarEvent.PROFIL:
        body: Profile();
        break;
    }

    return Scaffold(
      body: body,
      bottomBar: ...
    );
  }
} 

Answer 2

2022 年 1 月 27 日更新。https: //pub.dev/packages/flutter_riverpod/versions/1.0.3

这是另一种对我有用的方法，如果您也希望在拖动时控制“页面浏览 + 底部导航栏”：

class Index extends StateNotifier<int> {
  Index() : super(0);
  set value(int index) => state = index;
}

final indexProvider = StateNotifierProvider((ref) => Index());

class Home extends ConsumerWidget {
  static const route = '/home';
  const Home({Key? key}) : super(key: key);

  final List<Widget> fragments = const [
    Text('Page 1'),
    Text('Page 2'),
    Text('Page 3')
  ];

  final List<BottomNavigationBarItem> navItems = const [
    BottomNavigationBarItem(icon: Icon(Icons.home), label: 'Home'),
    BottomNavigationBarItem(icon: Icon(Icons.camera), label: 'Camera'),
    BottomNavigationBarItem(icon: Icon(Icons.edit), label: 'Edit'),
  ];

  final Text title = const Text('My App');

  @override
  Widget build(BuildContext context, WidgetRef ref) {
    final PageController controller = PageController();
    final int menuIndex = ref.watch(indexProvider) as int;
    return Scaffold(
      appBar: AppBar(title: title, actions: [
        IconButton(onPressed: () {}, icon: const Icon(Icons.list))
      ]),
      body: PageView(
          controller: controller,
          children: fragments,
          onPageChanged: (i) => ref.read(indexProvider.notifier).value = i),
      bottomNavigationBar: BottomNavigationBar(
          items: navItems,
          currentIndex: menuIndex,
          onTap: (i) {
            ref.read(indexProvider.notifier).value = i;
            controller.animateToPage(i,
                duration: const Duration(seconds: 1), curve: Curves.easeInOut);
          }),
    );
  }
}