flutter 底部bottomNavigationBar凸起效果

概要

     最近在做flutter 的时候，之前看到想实现 底部导航栏中间按钮 凸起效果, 最近想做又突然找不到方案了，因此记录下这里的实现方式。

预览效果

代码

主要使用 BottomAppBar 组建，以及配合FloatingActionButton ，具体全部代码如下：

import 'package:flutter/material.dart';
import 'package:flutter_app/src/pages/KBRandomWords.dart';
import "package:flutter_app/src/pages/KBWidgetPage.dart";
import 'kb_movie_review.dart';
import 'KBLoginPage.dart';
import 'src/widgets/cookbook/SnackBarDemo.dart';

class KBHome2 extends StatefulWidget {
  @override
  State<StatefulWidget> createState() {
    return _KBHomeState2();
  }
}

class _KBHomeState2 extends State<KBHome2> {
  int _currentIndex = 0;

  List<Widget> _pages;

  @override
  void initState() {
    super.initState();
    print("Home InitStatus");
    _pages = [
      new RandomWords(
        key: Key("random"),
      ),
      new KBMovieReview(key: Key("movie")),
      new KBLoginPage(),
      new KBWidgetPage(
        key: Key("widget"),
      ),
    ];
  }

  @override
  void dispose() {
    super.dispose();
    _pageController.dispose();
  }

  var _pageController = PageController(initialPage: 0);

  @override
  Widget build(BuildContext context) {
    return Scaffold(
      appBar: AppBar(
        title: Text("测试抽屉"),
      ),
      //      body: _pages[_currentIndex], // 只是这样写会导致在每次切换的时候 都rebuild 子控件
      body: PageView.builder(
          controller: _pageController,
          onPageChanged: _pageChanged,
          itemCount: _pages.length,
          itemBuilder: (context, index) => _pages[index]),

      floatingActionButton: FloatingActionButton(
        onPressed: () {},
        child: Icon(
          Icons.add,
          color: Colors.white,
        ),
      ),
      floatingActionButtonLocation: FloatingActionButtonLocation.centerDocked,

      bottomNavigationBar: BottomAppBar(

        color: Colors.red,
        shape: CircularNotchedRectangle(),
        child: Padding(
          padding: EdgeInsets.fromLTRB(0, 6, 0, 6),
          child: Row(
            mainAxisSize: MainAxisSize.max,
            mainAxisAlignment: MainAxisAlignment.spaceAround,
            children: <Widget>[
              GestureDetector(
                  onTap: () {
                    onTap(0);
                  },
                  child: Column(
                    mainAxisSize: MainAxisSize.min,
                    children: <Widget>[
                      Icon(Icons.home, color: getColor(0)),
                      Text("首页", style: TextStyle(color: getColor(0)))
                    ],
                  )),
              GestureDetector(
                  onTap: () {
                    onTap(1);
                  },
                  child: Column(
                    mainAxisSize: MainAxisSize.min,
                    children: <Widget>[
                      Icon(Icons.forum, color: getColor(1)),
                      Text("论坛", style: TextStyle(color: getColor(1)))
                    ],
                  )),
              Column(
                mainAxisSize: MainAxisSize.min,
                children: <Widget>[
                  Icon(
                    Icons.home,
                    color: Colors.transparent,
                  ),
                  Text("发布", style: TextStyle(color: Color(0xFFEEEEEE)))
                ],
              ),
              GestureDetector(
                  onTap: () {
                    onTap(2);
                  },
                  child: Column(
                    mainAxisSize: MainAxisSize.min,
                    children: <Widget>[
                      Icon(Icons.mail, color: getColor(2)),
                      Text("消息", style: TextStyle(color: getColor(2)))
                    ],
                  )),
              GestureDetector(
                  onTap: () {
                    onTap(3);
                  },
                  child: Column(
                    mainAxisSize: MainAxisSize.min,
                    children: <Widget>[
                      Icon(Icons.person, color: getColor(3)),
                      Text("我的", style: TextStyle(color: getColor(3)))
                    ],
                  ))
            ],
          ),
        ),
      ),
    );
  }

  Color getColor(int value) {
    return this._currentIndex == value ? Theme.of(context).cardColor : Color(0XFFBBBBBB);
  }

  void _pageChanged(int index) {
    setState(() {
      if (_currentIndex != index) _currentIndex = index;
    });
  }

  void onTap(int index) {
//        _pageController.jumpToPage(index);
    _pageController.animateToPage(index,
        duration: const Duration(milliseconds: 100), curve: Curves.easeOutSine);
  }
}

上面的pages 只要替换成自己的即可，

这里主要使用到了 以下代码实现：

   floatingActionButton: FloatingActionButton(
        onPressed: () {},
        child: Icon(
          Icons.add,
          color: Colors.white,
        ),
      ),
      floatingActionButtonLocation: FloatingActionButtonLocation.centerDocked,