Clifford attractor in a Flutter app

main.dart

import 'package:flutter/material.dart';
import 'dart:math' as Math;
import 'dart:async';
import 'dart:ui';

void main() {
  runApp(const MyApp());
}

class MyApp extends StatelessWidget {
  const MyApp({Key? key}) : super(key: key);
  
  @override
  Widget build(BuildContext context) {
    return MaterialApp(
      title: 'Attractor',
      theme: ThemeData(
        brightness: Brightness.dark
      ),
      home: const MyHomePage(title: 'Clifford Attractor'),
    );
  }
}

class MyHomePage extends StatefulWidget {
  const MyHomePage({Key? key, required this.title}) : super(key: key);

  final String title;

  @override
  State<MyHomePage> createState() => _MyHomePageState();
}

class CliffordAttractorPainter extends CustomPainter {
  List<Offset> points;
  CliffordAttractorPainter(this.points) : super();

  @override
  void paint(Canvas canvas, Size size) {
    Paint paint = Paint();
    paint.color = Colors.yellow.withOpacity(0.7);
    paint.style = PaintingStyle.fill;
    paint.strokeWidth = 1;
    canvas.drawPoints(PointMode.points, points, paint);
  }
  
  @override
  bool shouldRepaint(CliffordAttractorPainter oldDelegate) {
    return true;
  }
}

class _MyHomePageState extends State<MyHomePage> {
  
  num _a = -1.24;
  num _b = -1.2;
  num _c = -1.81;
  num _d = -1.9;
  
  Offset _currentOffset = Offset(0, 0);
  
  List<Offset> _points = [];
  int _count = 0;
  
  int _maxPoints = 100000;
  int _pointsPerCalculation = 10000;
  
  num _change = -1;
  
  void calculate() {
    if(_count > _maxPoints) {
      setState(() {
        _b += 0.01 * _change;
        _count = 0;
        if(_b < -2.11 || _b > -1.2) {
          _change *= -1;
        }
      });
      return;
    }
    if(_points.length > _maxPoints) {
      _points.removeRange(0, _pointsPerCalculation);
    }
    for(var i=0;i<_pointsPerCalculation;i++) {
      Offset o = Offset(
        Math.sin(_a * _currentOffset.dy) + _c * Math.cos(_a * _currentOffset.dx),
        Math.sin(_b * _currentOffset.dx) + _d * Math.cos(_b * _currentOffset.dy)
      );
      _count += 1;      
      _points.add(Offset(60 * _currentOffset.dx + 190, 90 * _currentOffset.dy + 300));      
      _currentOffset = o;
    }
    setState(() {
      _points = _points;
    });
  }
  
  @override
  void initState() {
    Timer.periodic(const Duration(milliseconds: 20), (_) { calculate(); });
  }

  @override
  Widget build(BuildContext context) {
    return Scaffold(
      appBar: AppBar(
        title: Text(widget.title),
      ),
      body: CustomPaint(
            painter: CliffordAttractorPainter(_points)
          )
    );
  }  
}