main.dart

import 'package:flutter/material.dart';

main() => runApp(MaterialApp(home: MyHomePage()));

class MyHomePage extends StatelessWidget {

  final itemWidth = 120.0;
  final itemHorizontalMargin = 4.0;

  @override
  Widget build(BuildContext context) {
    return Scaffold(
      appBar: AppBar(
        title: Text('Flutter 4 Fun'),
      ),
      body: Center(
        child: SizedBox(
          height: 200.0,
          child: ListView.builder(
            scrollDirection: Axis.horizontal,
            itemBuilder: (context, i) {
              return Container(
                width: itemWidth,
                height: 200,
                margin: EdgeInsets.symmetric(horizontal: itemHorizontalMargin),
                decoration: BoxDecoration(
                  color: Colors.purple,
                  borderRadius: BorderRadius.all(Radius.circular(4.0)),
                ),
                child: Center(
                  child: Text(
                    '$i',
                    style: TextStyle(
                      color: Colors.white,
                      fontWeight: FontWeight.bold,
                      fontSize: 22,
                    ),
                  ),
                ),
              );
            },
          ),
        ),
      ),
    );
  }
}