stockfish

The Stockfish Chess Engine for Flutter.

Also check out The Leela Chess Zero (lc0) neural network chess engine for flutter.

Architecture

This package wraps the Stockfish chess engine (C++) for use in Flutter applications on Android and iOS. It uses Dart FFI (Foreign Function Interface) to communicate between Dart and native C++ code.
For more information go to architecture.md.

Example

Check out this working chess game using this package by @PScottZero.

Also see the example folder for a minimal Flutter app demonstrating usage.

Usages

iOS project must have IPHONEOS_DEPLOYMENT_TARGET >=12.0.

Add dependency

Update dependencies section inside pubspec.yaml:

  stockfish: ^1.8.1

Init engine

import 'package:stockfish/stockfish.dart';

// create a new instance
final stockfish = Stockfish();

// state is a ValueListenable<StockfishState>
print(stockfish.state.value); # StockfishState.starting

// the engine takes a few moment to start
await Future.delayed(...)
print(stockfish.state.value); # StockfishState.ready

UCI command

Waits until the state is ready before sending commands.

stockfish.stdin = 'isready';
stockfish.stdin = 'go movetime 3000';
stockfish.stdin = 'go infinite';
stockfish.stdin = 'stop';

Engine output is directed to a Stream<String>, add a listener to process results.

stockfish.stdout.listen((line) {
  // do something useful
  print(line);
});

Dispose / Hot reload

There are two active isolates when Stockfish engine is running. That interferes with Flutter's hot reload feature so you need to dispose it before attempting to reload.

// sends the UCI quit command
stockfish.stdin = 'quit';

// or even easier...
stockfish.dispose();

Note: only one instance can be created at a time. The factory method Stockfish() will return null if it was called when an existing instance is active.