Bouncing Flutter logo deluxe

main.dart

import 'dart:async';
import 'dart:math';

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

// https://twitter.com/creativemaybeno/status/1323082856898404352?s=20

void main() {
  runApp(MaterialApp(
    debugShowCheckedModeBanner: false,
    home: Scaffold(
      body: ColoredBox(
        color: Colors.black,
        child: Center(
          child: AspectRatio(
            aspectRatio: 16 / 9,
            child: const BouncingFlutterLogo(),
          ),
        ),
      ),
    ),
  ));
}

class BouncingFlutterLogo extends StatefulWidget {
  const BouncingFlutterLogo({Key key}) : super(key: key);

  @override
  _BouncingFlutterLogoState createState() => _BouncingFlutterLogoState();
}

class _BouncingFlutterLogoState extends State<BouncingFlutterLogo> {
  final _logoKey = GlobalKey();
  Timer _updateTimer;

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

  @override
  void dispose() {
    _updateTimer.cancel();
    super.dispose();
  }

  var _color = Colors.white;

  var _x = .0, _y = .0, _dx = 1, _dy = 1;

  void _update() {
    final availableSize = (context.findRenderObject() as RenderBox).constraints,
        logoSize =
            (_logoKey.currentContext.findRenderObject() as RenderBox).size;

    final previousDx = _dx, previousDy = _dy;
    if (availableSize.maxWidth < _x + logoSize.width) {
      _dx = -1;
    } else if (_x < 0) {
      _dx = 1;
    }
    if (availableSize.maxHeight < _y + logoSize.height) {
      _dy = -1;
    } else if (_y < 0) {
      _dy = 1;
    }
    if (previousDx != _dx || previousDy != _dy) {
      final random = Random();
      _color = Color.fromRGBO(random.nextInt(59) + 196,
          random.nextInt(59) + 196, random.nextInt(59) + 196, 1);
    }

    setState(() {
      _x += _dx * 15;
      _y += _dy * 15;
    });
    _scheduleUpdate();
  }

  void _scheduleUpdate() {
    _updateTimer = Timer(
      // Lock the update rate, no matter the frame rate.
      Duration(milliseconds: 74),
      _update,
    );
  }

  @override
  Widget build(BuildContext context) {
    return SizedBox.expand(
      child: ColoredBox(
        color: _color,
        child: Stack(
          children: [
            AnimatedPositioned(
              top: _y,
              left: _x,
              duration: Duration(milliseconds: 74),
              child: RotatedBox(
                quarterTurns: _dy == 1
                    ? _dx == 1
                        ? 1
                        : 3
                    : 0,
                child: FlutterLogo(
                  key: _logoKey,
                  size: 256,
                  style: FlutterLogoStyle.stacked,
                ),
              ),
            ),
          ],
        ),
      ),
    );
  }
}