461 lines
16 KiB
Dart
461 lines
16 KiB
Dart
// Copyright 2013 The Flutter Authors. All rights reserved.
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// Use of this source code is governed by a BSD-style license that can be
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// found in the LICENSE file.
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import 'package:collection/collection.dart';
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import 'package:flutter/material.dart';
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import 'package:go_router/go_router.dart';
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final GlobalKey<NavigatorState> _rootNavigatorKey =
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GlobalKey<NavigatorState>(debugLabel: 'root');
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final GlobalKey<NavigatorState> _tabANavigatorKey =
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GlobalKey<NavigatorState>(debugLabel: 'tabANav');
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// This example demonstrates how to setup nested navigation using a
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// BottomNavigationBar, where each bar item uses its own persistent navigator,
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// i.e. navigation state is maintained separately for each item. This setup also
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// enables deep linking into nested pages.
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//
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// This example also demonstrates how build a nested shell with a custom
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// container for the branch Navigators (in this case a TabBarView).
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void main() {
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runApp(NestedTabNavigationExampleApp());
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}
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/// An example demonstrating how to use nested navigators
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class NestedTabNavigationExampleApp extends StatelessWidget {
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/// Creates a NestedTabNavigationExampleApp
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NestedTabNavigationExampleApp({super.key});
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final GoRouter _router = GoRouter(
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navigatorKey: _rootNavigatorKey,
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initialLocation: '/a',
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routes: <RouteBase>[
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StatefulShellRoute(
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builder: (BuildContext context, GoRouterState state,
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StatefulNavigationShell navigationShell) {
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// This nested StatefulShellRoute demonstrates the use of a
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// custom container for the branch Navigators. In this implementation,
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// no customization is done in the builder function (navigationShell
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// itself is simply used as the Widget for the route). Instead, the
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// navigatorContainerBuilder function below is provided to
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// customize the container for the branch Navigators.
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return navigationShell;
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},
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navigatorContainerBuilder: (BuildContext context,
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StatefulNavigationShell navigationShell, List<Widget> children) {
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// Returning a customized container for the branch
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// Navigators (i.e. the `List<Widget> children` argument).
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//
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// See ScaffoldWithNavBar for more details on how the children
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// are managed (using AnimatedBranchContainer).
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return ScaffoldWithNavBar(
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navigationShell: navigationShell, children: children);
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},
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branches: <StatefulShellBranch>[
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// The route branch for the first tab of the bottom navigation bar.
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StatefulShellBranch(
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navigatorKey: _tabANavigatorKey,
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routes: <RouteBase>[
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GoRoute(
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// The screen to display as the root in the first tab of the
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// bottom navigation bar.
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path: '/a',
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builder: (BuildContext context, GoRouterState state) =>
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const RootScreenA(),
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routes: <RouteBase>[
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// The details screen to display stacked on navigator of the
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// first tab. This will cover screen A but not the application
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// shell (bottom navigation bar).
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GoRoute(
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path: 'details',
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builder: (BuildContext context, GoRouterState state) =>
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const DetailsScreen(label: 'A'),
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),
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],
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),
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],
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),
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// The route branch for the third tab of the bottom navigation bar.
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StatefulShellBranch(
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// StatefulShellBranch will automatically use the first descendant
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// GoRoute as the initial location of the branch. If another route
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// is desired, specify the location of it using the defaultLocation
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// parameter.
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// defaultLocation: '/c2',
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routes: <RouteBase>[
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StatefulShellRoute(
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builder: (BuildContext context, GoRouterState state,
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StatefulNavigationShell navigationShell) {
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// Just like with the top level StatefulShellRoute, no
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// customization is done in the builder function.
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return navigationShell;
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},
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navigatorContainerBuilder: (BuildContext context,
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StatefulNavigationShell navigationShell,
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List<Widget> children) {
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// Returning a customized container for the branch
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// Navigators (i.e. the `List<Widget> children` argument).
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//
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// See TabbedRootScreen for more details on how the children
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// are managed (in a TabBarView).
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return TabbedRootScreen(
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navigationShell: navigationShell, children: children);
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},
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// This bottom tab uses a nested shell, wrapping sub routes in a
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// top TabBar.
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branches: <StatefulShellBranch>[
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StatefulShellBranch(routes: <GoRoute>[
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GoRoute(
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path: '/b1',
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builder: (BuildContext context, GoRouterState state) =>
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const TabScreen(
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label: 'B1', detailsPath: '/b1/details'),
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routes: <RouteBase>[
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GoRoute(
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path: 'details',
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builder:
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(BuildContext context, GoRouterState state) =>
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const DetailsScreen(
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label: 'B1',
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withScaffold: false,
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),
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),
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],
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),
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]),
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StatefulShellBranch(routes: <GoRoute>[
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GoRoute(
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path: '/b2',
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builder: (BuildContext context, GoRouterState state) =>
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const TabScreen(
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label: 'B2', detailsPath: '/b2/details'),
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routes: <RouteBase>[
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GoRoute(
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path: 'details',
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builder:
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(BuildContext context, GoRouterState state) =>
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const DetailsScreen(
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label: 'B2',
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withScaffold: false,
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),
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),
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],
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),
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]),
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],
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),
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],
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),
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],
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),
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],
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);
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@override
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Widget build(BuildContext context) {
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return MaterialApp.router(
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title: 'Flutter Demo',
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theme: ThemeData(
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primarySwatch: Colors.blue,
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),
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routerConfig: _router,
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);
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}
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}
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/// Builds the "shell" for the app by building a Scaffold with a
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/// BottomNavigationBar, where [child] is placed in the body of the Scaffold.
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class ScaffoldWithNavBar extends StatelessWidget {
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/// Constructs an [ScaffoldWithNavBar].
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const ScaffoldWithNavBar({
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required this.navigationShell,
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required this.children,
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Key? key,
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}) : super(key: key ?? const ValueKey<String>('ScaffoldWithNavBar'));
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/// The navigation shell and container for the branch Navigators.
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final StatefulNavigationShell navigationShell;
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/// The children (branch Navigators) to display in a custom container
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/// ([AnimatedBranchContainer]).
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final List<Widget> children;
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@override
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Widget build(BuildContext context) {
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return Scaffold(
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body: AnimatedBranchContainer(
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currentIndex: navigationShell.currentIndex,
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children: children,
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),
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bottomNavigationBar: BottomNavigationBar(
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// Here, the items of BottomNavigationBar are hard coded. In a real
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// world scenario, the items would most likely be generated from the
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// branches of the shell route, which can be fetched using
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// `navigationShell.route.branches`.
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items: const <BottomNavigationBarItem>[
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BottomNavigationBarItem(icon: Icon(Icons.home), label: 'Section A'),
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BottomNavigationBarItem(icon: Icon(Icons.work), label: 'Section B'),
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],
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currentIndex: navigationShell.currentIndex,
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onTap: (int index) => _onTap(context, index),
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),
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);
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}
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/// Navigate to the current location of the branch at the provided index when
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/// tapping an item in the BottomNavigationBar.
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void _onTap(BuildContext context, int index) {
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// When navigating to a new branch, it's recommended to use the goBranch
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// method, as doing so makes sure the last navigation state of the
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// Navigator for the branch is restored.
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navigationShell.goBranch(
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index,
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// A common pattern when using bottom navigation bars is to support
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// navigating to the initial location when tapping the item that is
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// already active. This example demonstrates how to support this behavior,
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// using the initialLocation parameter of goBranch.
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initialLocation: index == navigationShell.currentIndex,
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);
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}
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}
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/// Custom branch Navigator container that provides animated transitions
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/// when switching branches.
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class AnimatedBranchContainer extends StatelessWidget {
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/// Creates a AnimatedBranchContainer
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const AnimatedBranchContainer(
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{super.key, required this.currentIndex, required this.children});
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/// The index (in [children]) of the branch Navigator to display.
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final int currentIndex;
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/// The children (branch Navigators) to display in this container.
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final List<Widget> children;
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@override
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Widget build(BuildContext context) {
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return Stack(
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children: children.mapIndexed(
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(int index, Widget navigator) {
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return AnimatedScale(
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scale: index == currentIndex ? 1 : 1.5,
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duration: const Duration(milliseconds: 400),
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child: AnimatedOpacity(
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opacity: index == currentIndex ? 1 : 0,
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duration: const Duration(milliseconds: 400),
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child: _branchNavigatorWrapper(index, navigator),
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),
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);
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},
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).toList());
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}
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Widget _branchNavigatorWrapper(int index, Widget navigator) => IgnorePointer(
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ignoring: index != currentIndex,
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child: TickerMode(
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enabled: index == currentIndex,
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child: navigator,
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),
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);
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}
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/// Widget for the root page for the first section of the bottom navigation bar.
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class RootScreenA extends StatelessWidget {
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/// Creates a RootScreenA
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const RootScreenA({super.key});
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@override
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Widget build(BuildContext context) {
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return Scaffold(
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appBar: AppBar(
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title: const Text('Root of section A'),
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),
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body: Center(
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child: Column(
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mainAxisSize: MainAxisSize.min,
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children: <Widget>[
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Text('Screen A', style: Theme.of(context).textTheme.titleLarge),
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const Padding(padding: EdgeInsets.all(4)),
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TextButton(
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onPressed: () {
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GoRouter.of(context).go('/a/details');
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},
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child: const Text('View details'),
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),
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],
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),
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),
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);
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}
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}
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/// The details screen for either the A or B screen.
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class DetailsScreen extends StatefulWidget {
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/// Constructs a [DetailsScreen].
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const DetailsScreen({
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required this.label,
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this.param,
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this.withScaffold = true,
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super.key,
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});
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/// The label to display in the center of the screen.
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final String label;
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/// Optional param
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final String? param;
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/// Wrap in scaffold
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final bool withScaffold;
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@override
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State<StatefulWidget> createState() => DetailsScreenState();
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}
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/// The state for DetailsScreen
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class DetailsScreenState extends State<DetailsScreen> {
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int _counter = 0;
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@override
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Widget build(BuildContext context) {
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if (widget.withScaffold) {
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return Scaffold(
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appBar: AppBar(
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title: Text('Details Screen - ${widget.label}'),
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),
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body: _build(context),
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);
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} else {
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return Container(
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color: Theme.of(context).scaffoldBackgroundColor,
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child: _build(context),
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);
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}
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}
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Widget _build(BuildContext context) {
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return Center(
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child: Column(
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mainAxisSize: MainAxisSize.min,
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children: <Widget>[
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Text('Details for ${widget.label} - Counter: $_counter',
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style: Theme.of(context).textTheme.titleLarge),
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const Padding(padding: EdgeInsets.all(4)),
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TextButton(
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onPressed: () {
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setState(() {
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_counter++;
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});
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},
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child: const Text('Increment counter'),
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),
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const Padding(padding: EdgeInsets.all(8)),
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if (widget.param != null)
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Text('Parameter: ${widget.param!}',
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style: Theme.of(context).textTheme.titleMedium),
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const Padding(padding: EdgeInsets.all(8)),
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if (!widget.withScaffold) ...<Widget>[
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const Padding(padding: EdgeInsets.all(16)),
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TextButton(
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onPressed: () {
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GoRouter.of(context).pop();
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},
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child: const Text('< Back',
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style: TextStyle(fontWeight: FontWeight.bold, fontSize: 18)),
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),
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]
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],
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),
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);
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}
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}
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/// Builds a nested shell using a [TabBar] and [TabBarView].
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class TabbedRootScreen extends StatefulWidget {
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/// Constructs a TabbedRootScreen
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const TabbedRootScreen(
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{required this.navigationShell, required this.children, super.key});
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/// The current state of the parent StatefulShellRoute.
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final StatefulNavigationShell navigationShell;
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/// The children (branch Navigators) to display in the [TabBarView].
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final List<Widget> children;
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@override
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State<StatefulWidget> createState() => _TabbedRootScreenState();
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}
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class _TabbedRootScreenState extends State<TabbedRootScreen>
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with SingleTickerProviderStateMixin {
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late final TabController _tabController = TabController(
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length: widget.children.length,
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vsync: this,
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initialIndex: widget.navigationShell.currentIndex);
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@override
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void didUpdateWidget(covariant TabbedRootScreen oldWidget) {
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super.didUpdateWidget(oldWidget);
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_tabController.index = widget.navigationShell.currentIndex;
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}
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@override
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Widget build(BuildContext context) {
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final List<Tab> tabs = widget.children
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.mapIndexed((int i, _) => Tab(text: 'Tab ${i + 1}'))
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.toList();
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return Scaffold(
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appBar: AppBar(
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title: const Text('Root of Section B (nested TabBar shell)'),
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bottom: TabBar(
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controller: _tabController,
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tabs: tabs,
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onTap: (int tappedIndex) => _onTabTap(context, tappedIndex),
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)),
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body: TabBarView(
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controller: _tabController,
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children: widget.children,
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),
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);
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}
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void _onTabTap(BuildContext context, int index) {
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widget.navigationShell.goBranch(index);
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}
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}
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/// Widget for the pages in the top tab bar.
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class TabScreen extends StatelessWidget {
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/// Creates a RootScreen
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const TabScreen({required this.label, required this.detailsPath, super.key});
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/// The label
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final String label;
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/// The path to the detail page
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final String detailsPath;
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@override
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Widget build(BuildContext context) {
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return Center(
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child: Column(
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mainAxisSize: MainAxisSize.min,
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children: <Widget>[
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Text('Screen $label', style: Theme.of(context).textTheme.titleLarge),
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const Padding(padding: EdgeInsets.all(4)),
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TextButton(
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onPressed: () {
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GoRouter.of(context).go(detailsPath);
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},
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child: const Text('View details'),
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),
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],
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),
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);
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}
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}
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