overflow_bar_alignment_demo.dart

import 'package:flutter/material.dart';

class DemoRow extends StatelessWidget {
  DemoRow(this.alignment);

  final MainAxisAlignment alignment;

  @override
  Widget build(BuildContext context) {
    const List<Widget> items = <Widget>[
      Text('One'),
      Text('Two'),
      Text('Free'),
      Text('Four'),
    ];
    final Color backgroundColor = Directionality.of(context) == TextDirection.ltr ? Colors.green : Colors.yellow;
    return Padding(
      padding: EdgeInsets.symmetric(vertical: 8, horizontal: 16),
      child: Column(
        crossAxisAlignment: CrossAxisAlignment.start,
        children: <Widget>[
          Container(
            color: backgroundColor.withOpacity(0.15),
            child: Row(children: items, mainAxisAlignment: alignment),
          ),
          Container(
            color: backgroundColor.withOpacity(0.25),
            child: OverflowBar(children: items, alignment: alignment),
          ),
        ],
      ),
    );
  }
}

class AlignmentDemo extends StatelessWidget {
  @override
  Widget build(BuildContext context) {
    return Scaffold(
      body: SingleChildScrollView(
        child: Column(
          children: <Widget>[
            Directionality(
              textDirection: TextDirection.ltr,
              child: Column(
                children: <Widget>[
                  DemoRow(MainAxisAlignment.start),
                  DemoRow(MainAxisAlignment.center),
                  DemoRow(MainAxisAlignment.end),
                  DemoRow(MainAxisAlignment.spaceAround),
                  DemoRow(MainAxisAlignment.spaceBetween),
                  DemoRow(MainAxisAlignment.spaceEvenly),
                ],
              ),
            ),
            Directionality(
              textDirection: TextDirection.rtl,
              child: Column(
                children: <Widget>[
                  DemoRow(MainAxisAlignment.start),
                  DemoRow(MainAxisAlignment.center),
                  DemoRow(MainAxisAlignment.end),
                  DemoRow(MainAxisAlignment.spaceBetween),
                  DemoRow(MainAxisAlignment.spaceAround),
                  DemoRow(MainAxisAlignment.spaceEvenly),
                ],
              ),
            ),
          ],
        ),
      ),
    );
  }
}

void main() {
  runApp(MaterialApp(home: AlignmentDemo()));
}