NavigationBar简介

Material 3 导航栏组件! 导航栏提供了一种持久且便捷的方式来在应用程序的主要目的地之间进行切换。

使用场景：

底部菜单栏模块

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
labelBehavior	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

alwaysShow：图标与文本同时显示；

alwaysHide：文本同时隐藏；

onlyShowSelected：选中当前索引的菜单文本同时显示；

backgroundColor : 导航栏背景色 绿色

indicatorShape: 按钮背景样式

代码块：自行运行查看

import 'package:flutter/material.dart';

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

  @override
  State<NavigationBars> createState() => _NavigationBarsState();
}

class _NavigationBarsState extends State<NavigationBars> {

  int currentPageIndex = 0;
  NavigationDestinationLabelBehavior labelBehavior =
      NavigationDestinationLabelBehavior.alwaysShow;

  @override
  Widget build(BuildContext context) {
    return Scaffold(
      bottomNavigationBar: NavigationBar(
        labelBehavior: labelBehavior,
        selectedIndex: currentPageIndex,
        backgroundColor: Colors.green,
        indicatorColor: Colors.red,
        indicatorShape:  RoundedRectangleBorder(
          borderRadius: BorderRadius.circular(10.0),
          side: BorderSide(color: Colors.yellow, width: 2.0),
        ),
        surfaceTintColor: Colors.yellow,
        // animationDuration: Duration(milliseconds: 2000),
        // shadowColor: Colors.black,
        height: 70,
        elevation: 1,
        onDestinationSelected: (int index) {
          setState(() {
            currentPageIndex = index;
          });
        },
        destinations: const <Widget>[
          NavigationDestination(
            tooltip: "",
            icon: Icon(Icons.explore),
            label: 'Explore',
          ),
          NavigationDestination(
            icon: Icon(Icons.commute),
            label: 'Commute',
          ),
          NavigationDestination(
            selectedIcon: Icon(Icons.bookmark),
            icon: Icon(Icons.bookmark_border),
            label: 'Saved',
          ),
        ],
      ),
      body: Center(
        child: Column(
          mainAxisAlignment: MainAxisAlignment.center,
          children: <Widget>[
            Text('Label behavior: ${labelBehavior.name}'),
            const SizedBox(height: 10),
            OverflowBar(
              spacing: 10.0,
              children: <Widget>[
                ElevatedButton(
                  onPressed: () {
                    setState(() {
                      labelBehavior =
                          NavigationDestinationLabelBehavior.alwaysShow;
                    });
                  },
                  child: const Text('alwaysShow'),
                ),
                ElevatedButton(
                  onPressed: () {
                    setState(() {
                      labelBehavior =
                          NavigationDestinationLabelBehavior.onlyShowSelected;
                    });
                  },
                  child: const Text('onlyShowSelected'),
                ),
                ElevatedButton(
                  onPressed: () {
                    setState(() {
                      labelBehavior =
                          NavigationDestinationLabelBehavior.alwaysHide;
                    });
                  },
                  child: const Text('alwaysHide'),
                ),
              ],
            ),
          ],
        ),
      ),
    );
  }
}