NavigationRail 简介

一个 Material Design 小部件，旨在显示在应用程序的左侧或右侧，以便在少量视图（通常在三到五个视图之间）之间导航。

使用场景：

通过Row属性，左侧或右侧菜单栏按钮

属性	作用
onDestinationSelected	选择索引回调监听器
selectedIndex	目前选定目的地的索引
destinations	存放菜单按钮
backgroundColor	导航栏背景色
elevation	海拔高度
height	导航栏高度
labelType	是否展示菜单栏底部文字
shadowColor	阴影颜色
animationDuration	胶囊动画显示时长
indicatorShape	选中菜单背景圆角或者边框样式
indicatorColor	选中菜单背景色
leading	顶部菜单按钮
trailing	底部菜单按钮
groupAlignment	top,center,bottom 菜单按钮的显示位置
selectedLabelTextStyle	文字选择的样式
unselectedLabelTextStyle	文字未选择的样式
useIndicator	是否显示选中菜单背景色
minWidth	最小宽度

属性 groupAlignment: top、center、bottom

top

center

bottom

leading: 顶部菜单按钮

trailing： 底部菜单按钮

indicatorShape： 设置按钮背景圆角样式

代码块

import 'package:flutter/material.dart';

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

  @override
  State<NavigationRails> createState() => _NavigationRailsState();
}

class _NavigationRailsState extends State<NavigationRails> {
  int _selectedIndex = 0;
  NavigationRailLabelType labelType = NavigationRailLabelType.all;
  bool showLeading = false;
  bool showTrailing = false;
  double groupAlignment = -1.0;

  @override
  Widget build(BuildContext context) {
    return Scaffold(
      body: Row(
        children: <Widget>[
          NavigationRail(
            selectedIndex: _selectedIndex,
            groupAlignment: groupAlignment,
            onDestinationSelected: (int index) {
              setState(() {
                _selectedIndex = index;
              });
            },
            labelType: labelType,
            minExtendedWidth: 150,
            indicatorColor: Colors.red,
            indicatorShape:  RoundedRectangleBorder(
              borderRadius: BorderRadius.circular(10.0),
              side: BorderSide(color: Colors.yellow, width: 2.0),
            ),
            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: $groupAlignment'),
                const SizedBox(height: 10),
                OverflowBar(
                  spacing: 10.0,
                  children: <Widget>[
                    ElevatedButton(
                      onPressed: () {
                        setState(() {
                          groupAlignment = -1.0;
                        });
                      },
                      child: const Text('Top'),
                    ),
                    ElevatedButton(
                      onPressed: () {
                        setState(() {
                          groupAlignment = 0.0;
                        });
                      },
                      child: const Text('Center'),
                    ),
                    ElevatedButton(
                      onPressed: () {
                        setState(() {
                          groupAlignment = 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'),
                    ),
                  ],
                ),
              ],
            ),
          ),
        ],
      ),
    );
  }
}