bidirectional list view #flutter #bidirectional

BidirectionalListView.dart

// FROM: https://github.com/flutter/flutter/issues/20608

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

class EndlessListExampleApp extends StatelessWidget {
  @override
  Widget build(BuildContext context) {
    Key forwardListKey = UniqueKey();
    Widget forwardList = SliverList(
      delegate: SliverChildBuilderDelegate((BuildContext context, int index) {
        return Container(
          color: index % 2 == 0 ? Colors.green : Colors.yellow,
          child: Text('fordward $index'),
          height: 100.0,
        );
      }),
      key: forwardListKey,
    );

    Widget reverseList = SliverList(
      delegate: SliverChildBuilderDelegate((BuildContext context, int index) {
        return Container(
          color: index % 2 == 0 ? Colors.green : Colors.yellow,
          child: Text('reverse $index'),
          height: 100.0,
        );
      }),
    );

    return MaterialApp(
      home: Scaffold(
        appBar: AppBar(
          title: Text('Endless List'),
        ),
        body: Scrollable(
          viewportBuilder: (BuildContext context, ViewportOffset offset) {
            return Viewport(
              offset: offset,
              center: forwardListKey,
              slivers: [
                reverseList,
                forwardList,
              ],
            );
          },
        ),
      ),
    );
  }
}


void main() {
  runApp(EndlessListExampleApp());
}