overflow_view 0.2.2

A widget displaying children in a line with an overflow indicator at the end if there is not enough space.

example/lib/main.dart

import 'package:flutter/material.dart';
import 'package:overflow_view/overflow_view.dart';

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

class MyApp extends StatelessWidget {
  @override
  Widget build(BuildContext context) {
    return MaterialApp(
      title: 'Flutter Demo',
      theme: ThemeData(
        primarySwatch: Colors.blue,
        visualDensity: VisualDensity.adaptivePlatformDensity,
      ),
      home: MyHomePage(title: 'Flutter Demo Home Page'),
    );
  }
}

class MyHomePage extends StatefulWidget {
  MyHomePage({Key key, this.title}) : super(key: key);

  final String title;

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

class Avatar {
  const Avatar(this.initials, this.color);
  final String initials;
  final Color color;
}

const List<Avatar> avatars = <Avatar>[
  Avatar('AD', Colors.green),
  Avatar('JG', Colors.pink),
  Avatar('DA', Colors.blue),
  Avatar('JA', Colors.black),
  Avatar('CB', Colors.amber),
  Avatar('RR', Colors.deepPurple),
  Avatar('JD', Colors.pink),
  Avatar('MB', Colors.amberAccent),
  Avatar('AA', Colors.blueAccent),
  Avatar('BA', Colors.tealAccent),
  Avatar('CR', Colors.yellow),
];

class _MyHomePageState extends State<MyHomePage> {
  int _counter = 1;
  double ratio = 1;

  void _incrementCounter() {
    setState(() {
      _counter = (_counter + 1).clamp(0, avatars.length - 1);
    });
  }

  @override
  Widget build(BuildContext context) {
    return Scaffold(
      appBar: AppBar(
        title: Text(widget.title),
      ),
      body: SafeArea(
        child: Padding(
          padding: const EdgeInsets.all(8.0),
          child: Column(
            crossAxisAlignment: CrossAxisAlignment.start,
            children: [
              Text(
                'People',
                style: TextStyle(fontSize: 20),
              ),
              SizedBox(height: 20),
              OverflowView.flexible(
                spacing: -40,
                children: <Widget>[
                  for (int i = 0; i < _counter; i++)
                    AvatarWidget(
                      text: avatars[i].initials,
                      color: avatars[i].color,
                    )
                ],
                builder: (context, remaining) {
                  return AvatarWidget(
                    text: '+$remaining',
                    color: Colors.red,
                  );
                },
              ),
              SizedBox(height: 20),
              FractionallySizedBox(
                widthFactor: ratio,
                child: CommandBar(),
              ),
              SizedBox(height: 20),
              Expanded(
                child: OverflowView(
                  direction: Axis.vertical,
                  spacing: 4,
                  children: <Widget>[
                    for (int i = 0; i < _counter; i++)
                      AvatarWidget(
                        text: avatars[i].initials,
                        color: avatars[i].color,
                      )
                  ],
                  builder: (context, remaining) {
                    return SizedBox(
                      height: 80,
                      width: 80,
                      child: Stack(
                        fit: StackFit.expand,
                        children: [
                          if (remaining > 0)
                            AvatarOverview(
                              position: 0,
                              remaining: remaining,
                              counter: _counter,
                            ),
                          if (remaining > 1)
                            AvatarOverview(
                              position: 1,
                              remaining: remaining,
                              counter: _counter,
                            ),
                          if (remaining > 2)
                            AvatarOverview(
                              position: 2,
                              remaining: remaining,
                              counter: _counter,
                            ),
                          if (remaining > 3)
                            AvatarOverview(
                              position: 3,
                              remaining: remaining,
                              counter: _counter,
                            ),
                          Positioned.fill(
                            child: Center(
                              child: FractionallySizedBox(
                                alignment: Alignment.center,
                                widthFactor: 0.5,
                                heightFactor: 0.5,
                                child: FittedBox(
                                  child: AvatarWidget(
                                    text: '+$remaining',
                                    color: Colors.black.withOpacity(0.9),
                                  ),
                                ),
                              ),
                            ),
                          ),
                        ],
                      ),
                    );
                  },
                ),
              ),
              // Slider(
              //   value: ratio,
              //   min: 0,
              //   max: 1,
              //   divisions: 100,
              //   onChanged: (value) {
              //     setState(() {
              //       ratio = value;
              //     });
              //   },
              // ),
              SizedBox(height: 40),
            ],
          ),
        ),
      ),
      floatingActionButton: FloatingActionButton(
        onPressed: _incrementCounter,
        tooltip: 'Increment',
        child: Icon(Icons.add),
      ),
    );
  }
}

class AvatarOverview extends StatelessWidget {
  AvatarOverview({
    Key key,
    @required int remaining,
    @required int position,
    @required int counter,
  })  : index = counter - remaining + position,
        alignment = _getAlignment(position),
        super(key: key);

  final int index;
  final Alignment alignment;

  @override
  Widget build(BuildContext context) {
    final Avatar avatar = avatars[index];
    return FractionallySizedBox(
      key: ValueKey(index),
      alignment: alignment,
      widthFactor: 0.5,
      heightFactor: 0.5,
      child: FittedBox(
        child: AvatarWidget(
          text: avatar.initials,
          color: avatar.color,
        ),
      ),
    );
  }

  static Alignment _getAlignment(int position) {
    switch (position) {
      case 0:
        return Alignment.topLeft;
      case 1:
        return Alignment.topRight;
      case 2:
        return Alignment.bottomLeft;
      default:
        return Alignment.bottomRight;
    }
  }
}

class AvatarWidget extends StatelessWidget {
  const AvatarWidget({
    Key key,
    this.text,
    this.color,
  }) : super(key: key);

  final String text;
  final Color color;

  @override
  Widget build(BuildContext context) {
    return CircleAvatar(
      radius: 40,
      backgroundColor: color,
      foregroundColor: Colors.white,
      child: Text(
        text,
        style: TextStyle(fontSize: 30),
      ),
    );
  }
}

class CommandBar extends StatelessWidget {
  const CommandBar({
    Key key,
  }) : super(key: key);

  @override
  Widget build(BuildContext context) {
    final List<MenuItemData> commands = <MenuItemData>[
      MenuItemData(id: 'a', label: 'File'),
      MenuItemData(id: 'b', icon: Icons.save, label: 'Save'),
      MenuItemData(id: 'c', label: 'Edit'),
      MenuItemData(id: 'd', label: 'View'),
      MenuItemData(id: 'e', icon: Icons.exit_to_app),
      MenuItemData(id: 'f', label: 'Long Command'),
      MenuItemData(id: 'f', label: 'Very Long Command'),
      MenuItemData(id: 'f', label: 'Very very Long Command'),
      MenuItemData(id: 'f', label: 'Help'),
    ];

    return OverflowView.flexible(
      spacing: -4,
      children: [...commands.map((e) => _MenuItem(data: e))],
      builder: (context, remaining) {
        return PopupMenuButton<String>(
          icon: Icon(Icons.menu),
          itemBuilder: (context) {
            return commands
                .skip(commands.length - remaining)
                .map((e) => PopupMenuItem<String>(
                      value: e.id,
                      child: _MenuItem(data: e),
                    ))
                .toList();
          },
        );
      },
    );
  }
}

class MenuItemData {
  const MenuItemData({
    @required this.id,
    this.label,
    this.icon,
  });

  final String id;
  final String label;
  final IconData icon;
}

class _MenuItem extends StatelessWidget {
  const _MenuItem({
    Key key,
    @required this.data,
  }) : super(key: key);

  final MenuItemData data;

  @override
  Widget build(BuildContext context) {
    return FlatButton(
      onPressed: () {},
      child: Row(
        children: [
          if (data.icon != null) Icon(data.icon),
          if (data.icon != null && data.label != null) SizedBox(width: 8),
          if (data.label != null) Text(data.label),
        ],
      ),
    );
  }
}