BottomAppBar Floating action button notch/inset is not transparent

The problem is if you put your content in the body of Scaffold it won't overlap the size of your AppBar, BottomAppBar.

You can try using Stack, put your body as a first child, then put the Scaffold, change the backgroundColor as Transparent.

        @override
          Widget build(BuildContext context) {
            return Stack(
              children: <Widget>[
                Align(
                  alignment: Alignment.bottomCenter,
                  child: Image.network(
                      "https://images.pexels.com/photos/255379/pexels-photo-255379.jpeg?auto=compress&cs=tinysrgb&h=350"),
                ),
                Scaffold(
                  backgroundColor: Colors.transparent,
                  bottomNavigationBar: BottomAppBar(
                    color: Theme.of(context).accentColor,
                    shape: CircularNotchedRectangle(),
                    child: Row(
                      children: <Widget>[
                        IconButton(
                          icon: Icon(Icons.access_alarm),
                          onPressed: () => null,
                        ),
                        IconButton(
                          icon: Icon(Icons.sms_failed),
                          onPressed: () => null,
                        ),
                      ],
                    ),
                  ),
                  floatingActionButtonLocation:
                      FloatingActionButtonLocation.centerDocked,
                  floatingActionButton: FloatingActionButton(
                    backgroundColor: Theme.of(context).primaryColor,
                    child: Center(
                      child: Icon(
                        Icons.add,
                        size: 32.0,
                      ),
                    ),
                    onPressed: () {
                      /*
                    Navigator.push(
                        context,
                        MaterialPageRoute(builder: (context) => CreateEvent()),
                    );*/
                    },
                  ),
                ),
              ],
            ); 

I was able to achieve the desired behavior by also setting the resizeToAvoidBottomInset flag to false.

@override
Widget build(BuildContext context) {

    return Scaffold(
        extendBody: true,
        resizeToAvoidBottomInset: false,
        body: IndexedStack(
            children: <Widget>[],
            index: _selectedTab,
        ),
        bottomNavigationBar: ClipRRect(
            clipBehavior: Clip.antiAlias,
            borderRadius: BorderRadius.only(
                topLeft: Radius.circular(16.0),
                topRight: Radius.circular(16.0)
            ),
            child: BottomNavigationBar(
                backgroundColor: Colors.white,
                elevation: 10,
                type: BottomNavigationBarType.fixed,
                items: <BottomNavigationBarItem>[],
                currentIndex: _selectedTab,
            ),
        ),
    );
}

Edit: keep in mind that you may have to manually set the bottom insets by using MediaQuery.of(context)

You just need to be on the flutter channel: master and then add to Scaffold:

Scaffold(
   extendBody: true
);

and it should be transparent :)

Greets

Rebar

UPDATE:

You don't need to be on master channel. It's included everywhere :)