samples/poppopwin: upgrade to first-class sample

samples/third_party/pop-pop-win/web/_audio.dart

-part of game;
-
-class _Audio {
-  static const List<String> _AUDIO_NAMES =
-      const ['Pop0', 'Pop1', 'Pop2', 'Pop3', 'Pop4', 'Pop5', 'Pop6', 'Pop7', 'Pop8',
-             'Bomb0', 'Bomb1', 'Bomb2', 'Bomb3', 'Bomb4',
-             GameAudio.THROW_DART, GameAudio.FLAG, GameAudio.UNFLAG, GameAudio.CLICK, GameAudio.WIN];
-
-  final AudioLoader _audioLoader;
-  final Map<String, AudioBuffer> _buffers = new Map();
-  static final _audioFormat = _getAudioFormat();
-
-  factory _Audio() {
-    if(_audioFormat != null) {
-      try {
-        final audioContext = new AudioContext();
-        final loader = new AudioLoader(audioContext, _getAudioPaths(_AUDIO_NAMES));
-        return new _Audio._internal(loader);
-      } catch (e) {
-        print("Error creating AudioContext: ${e}");
-      }
-    }
-    return new _Audio._disabled();
-  }
-
-  _Audio._disabled() : this._audioLoader = null;
-
-  _Audio._internal(this._audioLoader) {
-    // TODO: less than ideal. Binding to event handlers defined in game.dart
-    // re-expose events? Take in handlers in ctor? Hmm...
-    _audioLoader.progress.listen(_onProgress);
-    _audioLoader.loaded.listen(_onLoaded);
-    _audioLoader.loaded.listen(_onLoad);
-    GameAudio.audioEvent.listen(_playAudio);
-    _audioLoader.load();
-  }
-
-  int get completedBytes {
-    if(_audioLoader == null) {
-      return 0;
-    } else {
-      return _audioLoader.completedBytes;
-    }
-  }
-
-  int get totalBytes {
-    if(_audioLoader == null) {
-      return 0;
-    } else {
-      return _audioLoader.totalBytes;
-    }
-  }
-
-  bool get done {
-    if(_audioLoader == null) {
-      return true;
-    } else {
-      return _audioLoader.state == ResourceLoader.StateLoaded;
-    }
-  }
-
-  AudioContext get _audioContext {
-    if(_audioLoader != null) {
-      return _audioLoader.context;
-    } else {
-      return null;
-    }
-  }
-
-  void _onLoad(args) {
-    assert(_buffers.length == 0);
-    for(final name in _AUDIO_NAMES) {
-      final path = _getAudioPath(name);
-      _buffers[name] = _audioLoader.getResource(path);
-    }
-  }
-
-  void _playAudio(String name) {
-    switch(name) {
-      case GameAudio.POP:
-        final i = rnd.nextInt(8);
-        name = '${GameAudio.POP}$i';
-        break;
-      case GameAudio.BOMB:
-        final i = rnd.nextInt(4);
-        name = '${GameAudio.BOMB}$i';
-        break;
-    }
-    _playAudioCore(name);
-  }
-
-  void _playAudioCore(String name) {
-    if(_audioContext != null) {
-      var source = _audioContext.createBufferSource();
-      final buffer = _buffers[name];
-      assert(buffer != null);
-      source.buffer = buffer;
-      source.connectNode(_audioContext.destination);
-      source.start(0);
-    }
-  }
-
-  static String _getAudioFormat() {
-    try {
-      final userAgent = window.navigator.userAgent;
-      final isWebKit = userAgent.contains("WebKit");
-      if(isWebKit) {
-        final isChrome = userAgent.contains("Chrome");
-        if(isChrome) {
-          return 'webm';
-        } else {
-          return 'm4a';
-        }
-      }
-    } catch (e) {
-      print("Error getting client info: ${e}");
-    }
-    return null;
-  }
-
-  static String _getAudioPath(String name) {
-    assert(_audioFormat != null);
-    return 'audio/${_audioFormat}/$name.${_audioFormat}';
-  }
-
-  static Iterable<String> _getAudioPaths(Iterable<String> names) {
-    return names.map(_getAudioPath);
-  }
-}