Zenn
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useTabControllerを使ってみた!

2023/10/08に公開
Flutter
Dart
hooks
tech

Overview

https://pub.dev/documentation/flutter_hooks/latest/flutter_hooks/useTabController.html
flutter_hooksには、useTabControllerというtabメニューを簡単に作成して制御できるWidgetがあるみたいです。
早速使ってみましたので、ご紹介します。

summary

自動的に破棄される TabController を作成します。

以下も参照してください。

タブコントローラー

本来のものだとこんなに長く書く。設定も複雑なですね。

main.dart
import 'package:flutter/material.dart';

/// Flutter code sample for [TabController].

void main() => runApp(const TabControllerExampleApp());

class TabControllerExampleApp extends StatelessWidget {
  const TabControllerExampleApp({super.key});

  @override
  Widget build(BuildContext context) {
    return const MaterialApp(
      home: TabControllerExample(),
    );
  }
}

const List<Tab> tabs = <Tab>[
  Tab(text: 'Zeroth'),
  Tab(text: 'First'),
  Tab(text: 'Second'),
];

class TabControllerExample extends StatelessWidget {
  const TabControllerExample({super.key});

  @override
  Widget build(BuildContext context) {
    return DefaultTabController(
      length: tabs.length,
      // The Builder widget is used to have a different BuildContext to access
      // closest DefaultTabController.
      child: Builder(builder: (BuildContext context) {
        final TabController tabController = DefaultTabController.of(context);
        tabController.addListener(() {
          if (!tabController.indexIsChanging) {
            // Your code goes here.
            // To get index of current tab use tabController.index
          }
        });
        return Scaffold(
          appBar: AppBar(
            bottom: const TabBar(
              tabs: tabs,
            ),
          ),
          body: TabBarView(
            children: tabs.map((Tab tab) {
              return Center(
                child: Text(
                  '${tab.text!} Tab',
                  style: Theme.of(context).textTheme.headlineSmall,
                ),
              );
            }).toList(),
          ),
        );
      }),
    );
  }
}

flutter_hooksを使うとこれは、UIが違いますがコードを簡潔に記述できます。

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

class HookTab extends HookWidget {
  const HookTab({super.key});

  @override
  Widget build(BuildContext context) {
    // TabControllerを作成
    final tabController = useTabController(initialLength: 2);

    return Scaffold(
      appBar: AppBar(
        backgroundColor: Colors.black87,
        title: const Text('Flutter Hooks Tabs'),
        // TabBarを設定
        bottom: TabBar(
          controller: tabController,
          tabs: const [
            Tab(text: 'Home'),
            Tab(text: 'Feed'),
          ],
        ),
      ),
      // TabBarViewを設定
      body: TabBarView(
        controller: tabController,
        children: const [
          // それぞれのタブに表示するWidgetを設定
          HomeTab(),
          FeedTab(),
        ],
      ),
    );
  }
}

// HomeのタブのWidget
class HomeTab extends StatelessWidget {
  const HomeTab({Key? key}) : super(key: key);

  @override
  Widget build(BuildContext context) {
    return const Scaffold(
      backgroundColor: Colors.yellowAccent,
      body: Center(child: Icon(Icons.home, size: 150)),
    );
  }
}

// FeedのタブのWidget
class FeedTab extends StatelessWidget {
  const FeedTab({Key? key}) : super(key: key);

  @override
  Widget build(BuildContext context) {
    return const Scaffold(
      backgroundColor: Colors.blueAccent,
      body: Center(child: Icon(Icons.feed, size: 150)),
    );
  }
}

こんな感じで動きます。

Riverpodを使用したパターン

まずはパッケージを追加してください。

name: widget_cook
description: A new Flutter project.
# The following line prevents the package from being accidentally published to
# pub.dev using `flutter pub publish`. This is preferred for private packages.
publish_to: 'none' # Remove this line if you wish to publish to pub.dev

# The following defines the version and build number for your application.
# A version number is three numbers separated by dots, like 1.2.43
# followed by an optional build number separated by a +.
# Both the version and the builder number may be overridden in flutter
# build by specifying --build-name and --build-number, respectively.
# In Android, build-name is used as versionName while build-number used as versionCode.
# Read more about Android versioning at https://developer.android.com/studio/publish/versioning
# In iOS, build-name is used as CFBundleShortVersionString while build-number is used as CFBundleVersion.
# Read more about iOS versioning at
# https://developer.apple.com/library/archive/documentation/General/Reference/InfoPlistKeyReference/Articles/CoreFoundationKeys.html
# In Windows, build-name is used as the major, minor, and patch parts
# of the product and file versions while build-number is used as the build suffix.
version: 1.0.0+1

environment:
  sdk: '>=3.1.0 <4.0.0'

# Dependencies specify other packages that your package needs in order to work.
# To automatically upgrade your package dependencies to the latest versions
# consider running `flutter pub upgrade --major-versions`. Alternatively,
# dependencies can be manually updated by changing the version numbers below to
# the latest version available on pub.dev. To see which dependencies have newer
# versions available, run `flutter pub outdated`.
dependencies:
  build_runner: ^2.4.6
  cupertino_icons: ^1.0.2
  flutter:
    sdk: flutter
  flutter_hooks: ^0.20.2
  hooks_riverpod: ^2.4.3
  riverpod_annotation: ^2.2.0
  riverpod_generator: ^2.3.3

dev_dependencies:
  flutter_lints: ^2.0.0
  flutter_test:
    sdk: flutter

# For information on the generic Dart part of this file, see the
# following page: https://dart.dev/tools/pub/pubspec
# The following section is specific to Flutter packages.
flutter:

  # The following line ensures that the Material Icons font is
  # included with your application, so that you can use the icons in
  # the material Icons class.
  uses-material-design: true
  # To add assets to your application, add an assets section, like this:
  # assets:
  #   - images/a_dot_burr.jpeg
  #   - images/a_dot_ham.jpeg
  # An image asset can refer to one or more resolution-specific "variants", see
  # https://flutter.dev/assets-and-images/#resolution-aware
  # For details regarding adding assets from package dependencies, see
  # https://flutter.dev/assets-and-images/#from-packages
  # To add custom fonts to your application, add a fonts section here,
  # in this "flutter" section. Each entry in this list should have a
  # "family" key with the font family name, and a "fonts" key with a
  # list giving the asset and other descriptors for the font. For
  # example:
  # fonts:
  #   - family: Schyler
  #     fonts:
  #       - asset: fonts/Schyler-Regular.ttf
  #       - asset: fonts/Schyler-Italic.ttf
  #         style: italic
  #   - family: Trajan Pro
  #     fonts:
  #       - asset: fonts/TrajanPro.ttf
  #       - asset: fonts/TrajanPro_Bold.ttf
  #         weight: 700
  #
  # For details regarding fonts from package dependencies,
  # see https://flutter.dev/custom-fonts/#from-packages

最近流行りのジェネレーターを使ってみました。プロバイダー書かなくていいからコードが短くなる。タブの状態管理は、Notifierを使用しています。デフォルトの値は0を指定。タブを押すと、表示されるWidgetが切り替わるようになっております。

import 'package:flutter/material.dart';
import 'package:hooks_riverpod/hooks_riverpod.dart';
import 'package:riverpod_annotation/riverpod_annotation.dart'; // このコードを書く

part 'tab_notifier.g.dart'; // note_providerのところは、ファイル名と同じにする.
// ファイルを自動生成するコマンド
// dart pub run build_runner watch --delete-conflicting-outputs

@riverpod
class TabControllerNotifier extends _$TabControllerNotifier {
  @override
  int build() => 0;

  void changeTab(int index) {
    state = index;
  }
}

class TabNotifier extends ConsumerWidget {
  const TabNotifier({Key? key}) : super(key: key);

  @override
  Widget build(BuildContext context, WidgetRef ref) {
    final tabIndex = ref.watch(tabControllerNotifierProvider);

    return DefaultTabController(
      length: 2,
      initialIndex: tabIndex,
      child: Scaffold(
        appBar: AppBar(
          title: const Text('generate Tabs'),
          bottom: TabBar(
            tabs: const [
              Tab(text: 'Home'),
              Tab(text: 'Feed'),
            ],
            onTap: (index) {
              ref.read(tabControllerNotifierProvider.notifier).changeTab(index);
            },
          ),
        ),
        body: const TabBarView(
          children: [
            HomeTab(),
            FeedTab(),
          ],
        ),
      ),
    );
  }
}

// HomeのタブのWidget
class HomeTab extends StatelessWidget {
  const HomeTab({Key? key}) : super(key: key);

  @override
  Widget build(BuildContext context) {
    return const Scaffold(
      backgroundColor: Colors.greenAccent,
      body: Center(child: Icon(Icons.home, size: 150)),
    );
  }
}

// FeedのタブのWidget
class FeedTab extends StatelessWidget {
  const FeedTab({Key? key}) : super(key: key);

  @override
  Widget build(BuildContext context) {
    return const Scaffold(
      backgroundColor: Colors.cyanAccent,
      body: Center(child: Icon(Icons.feed, size: 150)),
    );
  }
}

これが自動生成されたプロバイダー

// GENERATED CODE - DO NOT MODIFY BY HAND

part of 'tab_notifier.dart';

// **************************************************************************
// RiverpodGenerator
// **************************************************************************

String _$tabControllerNotifierHash() =>
    r'bd383293027a945c24e7ed9291cb36e3fc1d67e7';

/// See also [TabControllerNotifier].
@ProviderFor(TabControllerNotifier)
final tabControllerNotifierProvider =
    AutoDisposeNotifierProvider<TabControllerNotifier, int>.internal(
  TabControllerNotifier.new,
  name: r'tabControllerNotifierProvider',
  debugGetCreateSourceHash: const bool.fromEnvironment('dart.vm.product')
      ? null
      : _$tabControllerNotifierHash,
  dependencies: null,
  allTransitiveDependencies: null,
);

typedef _$TabControllerNotifier = AutoDisposeNotifier<int>;
// ignore_for_file: type=lint
// ignore_for_file: subtype_of_sealed_class, invalid_use_of_internal_member, invalid_use_of_visible_for_testing_member

main.dartは修正して使っているので、riverpodを使用したコードを使っていただいた方が良さそうです。

main.dart
import 'package:flutter/material.dart';
import 'package:hooks_riverpod/hooks_riverpod.dart';
import 'package:widget_cook/hook_tab.dart';
import 'package:widget_cook/tab_notifier.dart';
void main() {
  runApp(const ProviderScope(child: MyApp()));
}

class MyApp extends StatelessWidget {
  const MyApp({super.key});

  @override
  Widget build(BuildContext context) {
    return MaterialApp(
      debugShowCheckedModeBanner: false,
      title: 'Flutter Demo',
      theme: ThemeData(),
      home: const HookTab(),
      // home: const TabNotifier()
    );
  }
}

これが実際に動いているもの

thoughts

新しく入った仕事で、Tabを作る設定をflutter_hooksでやったりriverpodを使ったパターンを経験しました。作ったものはもっと複雑なロジックでしたが、Notifier使ってくれたらもっと簡潔に書ける気がしますね😅

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