flutter底部导航栏中间按钮凸起，导航栏中间部分凹陷效果

关键代码:
Scaffold中设置floatingActionButtonLocation: FloatingActionButtonLocation.centerDocked和extendBody: true，
BottomAppBar中设置shape: const CircularNotchedRectangle()

Scaffold(extendBody: true,//body是否延伸脚手架底部，在底部导航栏的边缘添加了凹口时，确保能看到body内容body: _body(),floatingActionButton: FloatingActionButton(backgroundColor: Colors.transparent,onPressed: () {isLogin().then((value) {if (value == true) {Utils().postDialog(context);} else {NavigatorUtil.push(LoginPage());}});},child: Image.asset(PathConfig.iconPublishGreen,width: 112.w,height: 112.w),),floatingActionButtonLocation: FloatingActionButtonLocation.centerDocked,bottomNavigationBar: _bottomNavigationAppBar(),);//中间凸出的底部导航栏(和floatingActionButton配合使用)_bottomNavigationAppBar(){return SizedBox(height: 110.w,child: BottomAppBar(color: Colors.white,shape: const CircularNotchedRectangle(),//添加一个凹口的形状child: Row(mainAxisAlignment: MainAxisAlignment.spaceAround,children: [// 首页底部图标Expanded(child: GestureDetector(child: _currentIndex == 0? Image.asset(PathConfig.iconLogoRound,width: 64.w,height: 64.w): Container(color: Colors.transparent,child: Column(mainAxisAlignment: MainAxisAlignment.center,children: <Widget>[Container(width: 40.w,height: 40.w,margin: EdgeInsets.only(bottom: 4.w),child: Image(image: AssetImage(PathConfig.iconUnselectAtui),),),Text(S.of(context).atui,style: TextStyle(fontSize: 20.sp,color: _currentIndex == 0 ? Color(0xffe63850) : Color(0xffD2D5D4)))],),),onTap: (){_changePage(0);})),// 商城底部图标Expanded(child: GestureDetector(child: Container(color: Colors.transparent,child: Column(mainAxisAlignment: MainAxisAlignment.center,children: <Widget>[Container(width: 40.w,height: 40.w,margin: EdgeInsets.only(bottom: 4.w),child: Image(image: AssetImage(_currentIndex == 1 ? PathConfig.iconSelectedMarket : PathConfig.iconUnselectMarket),),),Text(S.of(context).market,style: TextStyle(fontSize: 20.sp, color: _currentIndex == 1 ? JadeColors.green_2 : Color(0xffD2D5D4)))],),),onTap: (){_changePage(1);})),// 发布图标Expanded(child: GestureDetector(child: Column(children: <Widget>[Container(width: 40.w,height: 40.w,),/*Text(S.of(context).publish,style: TextStyle(fontSize: 13,color: JadeColors.green_2),)*/],),onTap: (){//_changePage(2);})),// 消息底部图标Expanded(child: GestureDetector(child: Container(color: Colors.transparent,// alignment: Alignment.center,child: Stack(alignment: Alignment.center,children: <Widget>[Column(mainAxisAlignment: MainAxisAlignment.center,children: [Container(width: 40.w,height: 40.w,margin: EdgeInsets.only(bottom: 4.w),child: Image(image: AssetImage(_currentIndex == 3 ? PathConfig.iconSelectedMessage : PathConfig.iconUnselectMessage),),),Text(S.of(context).xiaoxi,style: TextStyle(fontSize: 20.sp,color: _currentIndex == 3 ? JadeColors.green_2 : Color(0xffD2D5D4)),)],),Positioned(right: 40.w,top: 6.w,child: _messageCountView())],),),onTap: (){_changePage(3);},)),// 我的底部图标Expanded(child: GestureDetector(child: Container(color: Colors.transparent,child: Column(mainAxisAlignment: MainAxisAlignment.center,children: <Widget>[Container(width: 40.w,height: 40.w,margin: EdgeInsets.only(bottom: 4.w),child: Image(image: AssetImage(_currentIndex == 4 ? PathConfig.iconSelectedMine : PathConfig.iconUnselectMine),),),Text(S.of(context).wode,style: TextStyle(fontSize: 20.sp,color: _currentIndex == 4 ? JadeColors.green_2 : Color(0xffD2D5D4)),)],)),onTap: (){_changePage(4);},))],),),);}