Rolling List - by Simon Lightfoot - Humpday Q&A :: 20th December 2023 #HumpdayQandA #Flutter #Dart - https://www.youtube.com/live/kJWtSAFnJxk?si=g1KOkJDxgvjVJmZM&t=5278

rolling_list.dart

// MIT License
//
// Copyright (c) 2023 Simon Lightfoot
//
// Permission is hereby granted, free of charge, to any person obtaining a copy
// of this software and associated documentation files (the "Software"), to deal
// in the Software without restriction, including without limitation the rights
// to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
// copies of the Software, and to permit persons to whom the Software is
// furnished to do so, subject to the following conditions:
//
// The above copyright notice and this permission notice shall be included in all
// copies or substantial portions of the Software.
//
// THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
// IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
// FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
// AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
// LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
// OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
// SOFTWARE.
//
import 'dart:async';

import 'package:flutter/material.dart';

void main() {
  runApp(MaterialApp(
    debugShowCheckedModeBanner: false,
    theme: ThemeData.light(),
    home: const Home(),
  ));
}

class Home extends StatefulWidget {
  const Home({super.key});

  @override
  State<Home> createState() => _HomeState();
}

class _HomeState extends State<Home> {
  late final List<String> _data;
  late final Timer _timer;
  int _count = 0;

  @override
  void initState() {
    super.initState();
    _data = List.generate(
      20,
      (index) => 'Happy Christmas $index',
    );
    _timer = Timer.periodic(
      const Duration(seconds: 3),
      _onTimerTick,
    );
  }

  void _onTimerTick(_) {
    setState(() {
      _data.removeAt(0);
      _data.add('Timer Item $_count');
      _count++;
    });
  }

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

  @override
  Widget build(BuildContext context) {
    return Material(
      child: ListView.builder(
        itemCount: _data.length,
        itemBuilder: (BuildContext context, int index) {
          final item = _data[index];
          return AspectRatio(
            key: Key('data-$item'),
            aspectRatio: 3 / 1,
            child: Placeholder(
              color: Colors.grey.shade200,
              child: Center(
                child: Text(
                  item,
                  style: const TextStyle(
                    color: Colors.black,
                    fontSize: 32.0,
                  ),
                ),
              ),
            ),
          );
        },
      ),
    );
  }
}