notched_container

import 'package:flutter/material.dart';
import 'package:flutter/widgets.dart';

class NotchedContainer extends StatelessWidget {
  final Widget child;
  final Widget notchContent;
  final double notchPadding;
  final double notchOffsetRight;
  final EdgeInsets contentPadding;
  final Alignment notchPosition;
  final double radius;
  final Color color;

  NotchedContainer(
      {@required this.child,
      @required this.radius,
      @required this.notchContent,
      this.notchPosition = Alignment.topCenter,
      this.notchPadding = 5,
      this.notchOffsetRight = 0,
      this.contentPadding = EdgeInsets.zero,
      this.color = Colors.transparent});

  Widget _notchContent() {
    if (notchPosition == Alignment.topCenter)
      return Positioned(
        left:0, right:0,
        child: notchContent,
      );
    else if (notchPosition == Alignment.topRight)
      return Positioned(
        right: notchOffsetRight + notchPadding,
        height: radius * 2,
        width: radius * 2,
        child: notchContent,
      );
    else
      throw Exception("Unsupported notch alignment : $notchPosition ");
  }

  @override
  Widget build(BuildContext context) {
    return Stack(children: [
      Positioned(
          top: radius,
          left: 0,
          right: 0,
          bottom: 0,
          child: PhysicalShape(
            color: color,
            clipBehavior: Clip.hardEdge,
            clipper: _NotchClipper(
                radius: radius,
                padding: notchPadding,
                offsetRight: notchOffsetRight,
                notchPosition: notchPosition),
            child: Container(padding: contentPadding, child: child),
          )),
      _notchContent()
    ]);
  }
}

class _NotchClipper extends CustomClipper<Path> {
  final double offsetRight;
  final double padding;
  final double radius;
  final Alignment notchPosition;

  _NotchClipper(
      {this.radius, this.padding, this.notchPosition, this.offsetRight = 0});

  @override
  Path getClip(Size size) {
    var shape = AutomaticNotchedShape(ContinuousRectangleBorder(),
        RoundedRectangleBorder(borderRadius: BorderRadius.circular(99)));
    if (notchPosition == Alignment.topCenter)
      return shape.getOuterPath(
          Offset.zero & size,
          Offset((size.width / 2) - radius - padding, -radius - padding) &
              Size((padding + radius) * 2, (padding + radius) * 2));
    else if (notchPosition == Alignment.topRight)
      return shape.getOuterPath(
          Offset.zero & size,
          Offset(size.width - ((radius + padding) * 2) - offsetRight, -radius - padding) &
              Size((radius + padding) * 2, (radius + padding) * 2));
    else
      throw Exception("Unsupported notch position $notchPosition");
  }

  @override
  bool shouldReclip(CustomClipper<Path> oldClipper) {
    return true;
  }
}