flutter/examples/api/lib/material/navigation_rail/navigation_rail.1.dart

// Copyright 2014 The Flutter Authors. All rights reserved.
// Use of this source code is governed by a BSD-style license that can be
// found in the LICENSE file.

// Flutter code sample for NavigationRail

import 'package:flutter/material.dart';

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

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

  @override
  Widget build(BuildContext context) {
    return MaterialApp(
      theme: ThemeData(colorSchemeSeed: const Color(0xff6750a4), useMaterial3: true),
      home: const NavRailExample(),
    );
  }
}

class NavRailExample extends StatefulWidget {
  const NavRailExample({super.key});

  @override
  State<NavRailExample> createState() => _NavRailExampleState();
}

class _NavRailExampleState extends State<NavRailExample> {
  int _selectedIndex = 0;
  NavigationRailLabelType labelType = NavigationRailLabelType.all;
  bool showLeading = false;
  bool showTrailing = false;
  double groupAligment = -1.0;

  @override
  Widget build(BuildContext context) {
    return Scaffold(
      body: SafeArea(
        child: Row(
          children: <Widget>[
            NavigationRail(
              selectedIndex: _selectedIndex,
              groupAlignment: groupAligment,
              onDestinationSelected: (int index) {
                setState(() {
                  _selectedIndex = index;
                });
              },
              labelType: labelType,
              leading: showLeading ? FloatingActionButton(
                elevation: 0,
                onPressed: () {
                  // Add your onPressed code here!
                },
                child: const Icon(Icons.add),
              ) : const SizedBox(),
              trailing: showTrailing ? IconButton(
                onPressed: () {
                  // Add your onPressed code here!
                },
                icon: const Icon(Icons.more_horiz_rounded),
              ) : const SizedBox(),
              destinations: const <NavigationRailDestination>[
                NavigationRailDestination(
                  icon: Icon(Icons.favorite_border),
                  selectedIcon: Icon(Icons.favorite),
                  label: Text('First'),
                ),
                NavigationRailDestination(
                  icon: Icon(Icons.bookmark_border),
                  selectedIcon: Icon(Icons.book),
                  label: Text('Second'),
                ),
                NavigationRailDestination(
                  icon: Icon(Icons.star_border),
                  selectedIcon: Icon(Icons.star),
                  label: Text('Third'),
                ),
              ],
            ),
            const VerticalDivider(thickness: 1, width: 1),
            // This is the main content.
            Expanded(
              child: Column(
                mainAxisAlignment: MainAxisAlignment.center,
                children: <Widget>[
                  Text('selectedIndex: $_selectedIndex'),
                  const SizedBox(height: 20),
                  Text('Label type: ${labelType.name}'),
                  const SizedBox(height: 10),
                  OverflowBar(
                    spacing: 10.0,
                    children: <Widget>[
                      ElevatedButton(
                        onPressed: () {
                          setState(() {
                            labelType = NavigationRailLabelType.none;
                          });
                        },
                        child: const Text('None'),
                      ),
                      ElevatedButton(
                        onPressed: () {
                          setState(() {
                            labelType = NavigationRailLabelType.selected;
                          });
                        },
                        child: const Text('Selected'),
                      ),
                      ElevatedButton(
                        onPressed: () {
                          setState(() {
                            labelType = NavigationRailLabelType.all;
                          });
                        },
                        child: const Text('All'),
                      ),
                    ],
                  ),
                  const SizedBox(height: 20),
                  Text('Group alignment: $groupAligment'),
                  const SizedBox(height: 10),
                  OverflowBar(
                    spacing: 10.0,
                    children: <Widget>[
                      ElevatedButton(
                        onPressed: () {
                          setState(() {
                            groupAligment = -1.0;
                          });
                        },
                        child: const Text('Top'),
                      ),
                      ElevatedButton(
                        onPressed: () {
                          setState(() {
                            groupAligment = 0.0;
                          });
                        },
                        child: const Text('Center'),
                      ),
                      ElevatedButton(
                        onPressed: () {
                          setState(() {
                            groupAligment = 1.0;
                          });
                        },
                        child: const Text('Bottom'),
                      ),
                    ],
                  ),
                  const SizedBox(height: 20),
                  OverflowBar(
                    spacing: 10.0,
                    children: <Widget>[
                      ElevatedButton(
                        onPressed: () {
                          setState(() {
                            showLeading = !showLeading;
                          });
                        },
                        child: Text(showLeading ? 'Hide Leading' : 'Show Leading'),
                      ),
                      ElevatedButton(
                        onPressed: () {
                          setState(() {
                            showTrailing = !showTrailing;
                          });
                        },
                        child: Text(showTrailing ? 'Hide Trailing' : 'Show Trailing'),
                      ),
                    ],
                  ),
                ],
              ),
            ),
          ],
        ),
      ),
    );
  }
}