Create Round Bottom AppBar in Flutter

In this article, we will try creating an AppBar with round bottom.

Use AppBar’s shape

If you want to adjust the height of the AppBar, just modify the barHeight property. kToolbarHeight is the height of the toolbar component of the AppBar, which is a constant with the value of 56.0.

Firstly, create a widget which define the appbar.

class RoundAppBar extends StatelessWidget with PreferredSizeWidget{
  final double barHeight = 50;
  final String title;

  RoundAppBar({Key key, this.title}) : super(key: key);

  @override
  Size get preferredSize => Size.fromHeight(kToolbarHeight + barHeight);

  @override
  Widget build(BuildContext context) {
    return AppBar(
      title: Center(child: Text(title)),
      shape: RoundedRectangleBorder(
        borderRadius: BorderRadius.vertical(
          bottom: Radius.circular(48.0),
        ),
      ),
      actions: [
        Icon(Icons.dehaze)
      ],
    );
  }
}

We can include it in a Scaffold like this:

Scaffold(
      appBar: RoundAppBar(title: 'Round AppBar',),
      backgroundColor: Colors.white,
      body: SafeArea(
        child: Center(child: Text('Body'),)
      ),
    );

Use ClipPath

To use ClipPath, we need 2 parts. The first one is a normal rectangle AppBar and a ClipPath under it with the same color.

class HomePage extends StatefulWidget {
  @override
  _HomePageState createState() => _HomePageState();
}

class _HomePageState extends State<HomePage> {
  @override
  Widget build(BuildContext context) {
    return Scaffold(
      appBar: AppBar(
        title: Center(child: Text('Round AppBar')),
        backgroundColor: Colors.lightGreen,
        elevation: 0,
        actions: [Icon(Icons.dehaze_sharp)],
      ),
      body: SafeArea(
          child: Column(
        children: [
          ClipPath(
            clipper: RoundShape(),
            child: Container(
              height: 40,
              color: Colors.lightGreen,
            ),
          ),
          Center(
            child: Text('Body'),
          ),
        ],
      )),
    );
  }
}

class RoundShape extends CustomClipper<Path> {
  @override
  getClip(Size size) {
    double height = size.height;
    double width = size.width;
    double curveHeight = size.height / 2;

    var p = Path();
    p.lineTo(0, height - curveHeight);
    p.quadraticBezierTo(width / 2, height, width, height - curveHeight);
    p.lineTo(width, 0);
    p.close();

    return p;
  }

  @override
  bool shouldReclip(CustomClipper oldClipper) => true;
}