DiscoBox with TweenColor sequence

main.dart

import 'package:flutter/material.dart';

void main() => runApp(MaterialApp(
      home: DiscoBox(colors: const [Colors.red, Colors.green, Colors.blue]),
    ));

class DiscoBox extends StatefulWidget {
  final List<Color> colors;

  DiscoBox({@required this.colors});

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

class _DiscoBoxState extends State<DiscoBox> with TickerProviderStateMixin {
  AnimationController _controller;
  Animation<Color> _tween;

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

    _controller = AnimationController(vsync: this)
      ..repeat(period: const Duration(seconds: 1));

    _tween =
        TweenSequence<Color>(_listOf(widget.colors)).animate(_controller.view);
  }

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

  @override
  Widget build(BuildContext context) => AnimatedBuilder(
        animation: _controller.view,
        builder: (_, __) =>
            Container(decoration: BoxDecoration(color: _tween.value)),
      );

  static List<TweenSequenceItem<Color>> _listOf(List<Color> colors) {
    final l = List<TweenSequenceItem<Color>>(colors.length);
    for (int i = 0; i < colors.length; i++) {
      final a = colors[i];
      final b = i < colors.length - 1 ? colors[i + 1] : colors[0];
      l[i] = TweenSequenceItem(tween: ColorTween(begin: a, end: b), weight: 1);
    }
    return l;
  }
}