Disc animation.dart

Disc animation

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

class DiscData {
  static final _rng = Random();

  final double size;
  final Color color;
  final Alignment alignment;

  DiscData()
      : size = _rng.nextDouble() * 40 + 10,
        color = Color.fromARGB(
          _rng.nextInt(200),
          _rng.nextInt(255),
          _rng.nextInt(255),
          _rng.nextInt(255),
        ),
        alignment = Alignment(
          _rng.nextDouble() * 2 - 1,
          _rng.nextDouble() * 2 - 1,
        );
}

void main() async {
  runApp(
    MaterialApp(
      debugShowCheckedModeBanner: false,
      home: Scaffold(
        body: Container(
          color: const Color(0xFF15202D),
          child: const SizedBox.expand(
            child: VariousDiscs(50),
          ),
        ),
      ),
    ),
  );
}

class VariousDiscs extends StatefulWidget {
  final int numberOfDiscs;

  const VariousDiscs(this.numberOfDiscs);

  @override
  State<VariousDiscs> createState() => _VariousDiscsState();
}

class _VariousDiscsState extends State<VariousDiscs> {
  final _discs = <DiscData>[];

  @override
  void initState() {
    super.initState();
    _makeDiscs();
  }

  void _makeDiscs() {
    _discs.clear();
    for (int i = 0; i < widget.numberOfDiscs; i++) {
      _discs.add(DiscData());
    }
  }

  @override
  Widget build(BuildContext context) {
    return Stack(
      children: [
        const Center(
          child: Text(
            'Click a disc!',
            style: TextStyle(color: Colors.white, fontSize: 50),
          ),
        ),
        GestureDetector(
          onTap: () => setState(() {
            _makeDiscs();
          }),
          child: Stack(children: [
            for (final disc in _discs)
              Positioned.fill(
                child: AnimatedAlign(
                  duration: const Duration(milliseconds: 500),
                  curve: Curves.easeInOut,
                  alignment: disc.alignment,
                  child: AnimatedContainer(
                    duration: const Duration(milliseconds: 500),
                    decoration: BoxDecoration(
                      color: disc.color,
                      shape: BoxShape.circle,
                    ),
                    height: disc.size,
                    width: disc.size,
                  ),
                ),
              ),
          ]),
        ),
      ],
    );
  }
}