gistfile1.txt

import 'package:flutter/material.dart';

void main() {
  runApp(App());
}

class App extends StatefulWidget {
  @override
  State<App> createState() => _AppState();
}

class _AppState extends State<App> with SingleTickerProviderStateMixin {
  AnimationController _controller;

  @override
  void initState() {
    super.initState();
    _controller =
        AnimationController(vsync: this, duration: const Duration(seconds: 5))
          ..repeat();
  }

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

  @override
  Widget build(BuildContext context) {
    return MaterialApp(
      title: 'My App',
      home: Scaffold(
        appBar: AppBar(title: Text('Say hello to flutter on web!')),
        body: AnimatedBuilder(
          animation: _controller,
          builder: (_, __) {
            return ClipPath(
              clipper: MyClipper(),
              child: Container(
                decoration: BoxDecoration(
                  gradient: RadialGradient(
                    center: Alignment(0, 0),
                    radius: 2,
                    colors: [
                      Colors.yellow,
                      Colors.transparent,
                    ],
                    stops: [0, _controller.value],
                  ),
                ),
              ),
            );
          },
        ),
      ),
    );
  }
}

class MyClipper extends CustomClipper<Path> {
  @override
  Path getClip(Size size) {
//     return Path()
//             ..moveTo(size.width / 3, 0)
//             ..lineTo(0, size.height)
//             ..lineTo(size.width, size.height)
//             ..lineTo(size.width * 2 / 3, 0);

//     return Path()
//       ..moveTo(20, size.height - 20)
//       ..quadraticBezierTo(-100, -100, size.width - 20, 20)
//       ..quadraticBezierTo(
//           size.width - -100, size.height - -100, 20, size.height - 20);
    
    return Path()
            ..lineTo(0, 200)
            ..lineTo(200, 200)
            ..lineTo(200, 0)
            ..lineTo(0, 0)
            ..moveTo(size.width - 200, size.height - 200)
            ..lineTo(size.width - 200, size.height)
            ..lineTo(size.width, size.height)
            ..lineTo(size.width, size.height - 200)
            ..lineTo(size.width - 200, size.height - 200);
  }

  @override
  bool shouldReclip(_) => false;
}