section_loop 0.1.0

Player-agnostic A-B section looping for audio apps. Loop a named part of a track on any player, with the seek-storm and queue-stall bugs handled.

example/section_loop_example.dart

import 'package:section_loop/section_loop.dart';

/// A stand-in for a real audio player, so the example runs anywhere.
class FakePlayer {
  Duration position = Duration.zero;
  bool playing = true;
  final Duration duration = const Duration(minutes: 3);

  Future<void> seek(Duration to) async {
    position = to;
    print('  seek -> ${to.inSeconds}s');
  }

  Future<void> pause() async {
    playing = false;
    print('  pause');
  }

  Future<void> play() async => playing = true;
}

Future<void> main() async {
  final player = FakePlayer();

  final engine = SectionLoopEngine(
    onSeek: player.seek,
    onPause: player.pause,
    onPlay: player.play,
  )..section = LoopSection(
      name: 'Chorus',
      start: const Duration(seconds: 48),
      end: const Duration(seconds: 52),
    );

  print('Looping ${engine.section!.name} '
      '(${engine.section!.start.inSeconds}s-${engine.section!.end.inSeconds}s)');

  // Advance playback a second at a time. After the engine seeks, playback
  // continues from the section start, so the loop repeats on its own.
  player.position = const Duration(seconds: 50);
  for (var tick = 0; tick < 8; tick++) {
    print('at ${player.position.inSeconds}s');
    engine.handlePosition(player.position, trackDuration: player.duration);
    await Future<void>.delayed(Duration.zero); // let the seek settle
    player.position += const Duration(seconds: 1);
  }

  // Sections persist as JSON.
  final json = engine.section!.toJson();
  print('stored: $json');
  print('restored: ${LoopSection.fromJson(json)}');
}