slot_machine_effect 0.0.3

A slot machine reel for Flutter. Spins up, drifts to a stop on the value you ask for, and rocks into place with a small bounce.

example/lib/main.dart

import 'dart:math';

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

void main() => runApp(const ExampleApp());

/// The blank face the reel parks on before the first spin. Not a digit, so
/// it cannot be confused with a result.
const _blank = -1;

/// Everything on the reel: the ten digits, plus the blank.
const _reelValues = [0, 1, 2, 3, 4, 5, 6, 7, 8, 9, _blank];

class ExampleApp extends StatelessWidget {
  const ExampleApp({super.key});

  @override
  Widget build(BuildContext context) {
    return MaterialApp(
      title: 'Slot Machine Effect',
      theme: ThemeData(
        colorScheme: ColorScheme.fromSeed(seedColor: Colors.blue),
        useMaterial3: true,
      ),
      home: const SlotMachineDemoPage(),
    );
  }
}

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

  @override
  State<SlotMachineDemoPage> createState() => _SlotMachineDemoPageState();
}

class _SlotMachineDemoPageState extends State<SlotMachineDemoPage> {
  final _random = Random();
  int _target = 0;
  bool _spinning = false;
  bool _spunOnce = false;

  void _spin() {
    setState(() {
      // A spin is triggered by `target` changing, so keep drawing until we
      // get a different value — otherwise a repeat would do nothing.
      int next;
      do {
        next = _random.nextInt(10);
      } while (next == _target);
      _target = next;
      _spunOnce = true;
    });
  }

  String get _status {
    if (_spinning) return 'Spinning to $_target…';
    return _spunOnce ? 'Landed on $_target' : 'Tap spin to start';
  }

  @override
  Widget build(BuildContext context) {
    return Scaffold(
      appBar: AppBar(title: const Text('Slot Machine Effect')),
      body: Center(
        child: Column(
          mainAxisSize: MainAxisSize.min,
          children: [
            SlotMachineReel(
              height: 125,
              width: 300,
              // The reel shows the blank until the first spin. Without a
              // placeholder it would rest on `target`.
              values: _reelValues,
              placeholder: _blank,
              target: _target,
              bounceDuration: const Duration(milliseconds: 888),
              onSpinStart: () => setState(() => _spinning = true),
              onSettled: () => setState(() => _spinning = false),
              itemBuilder: (e) => Container(
                margin: const EdgeInsets.symmetric(vertical: 10),
                height: 118.96,
                width: 241,
                alignment: Alignment.center,
                decoration: const BoxDecoration(color: Colors.blue),
                child: Text(
                  e == _blank ? '?' : '$e',
                  style: Theme.of(context).primaryTextTheme.headlineLarge
                      ?.copyWith(color: Colors.white),
                ),
              ),
            ),
            const SizedBox(height: 24),
            Text(_status),
            const SizedBox(height: 12),
            ElevatedButton(
              onPressed: _spinning ? null : _spin,
              child: const Text('Spin'),
            ),
          ],
        ),
      ),
    );
  }
}