The AudioManager class is the main entry point to the simple_audio library. You can create AudioClips and AudioSources with the manager. You can play clips from sources with the manager.

The AudioManager also has a listener which picks up sounds from AudioSources. The sound picked up by the listener from the AudioSources is played through the real, physical speakers attached to the computer.

class AudioManager {
 AudioContext _context;
 AudioDestinationNode _destination;
 AudioListener _listener;

 GainNode _masterGain;
 GainNode _musicGain;
 GainNode _sourceGain;

 String baseURL;

 Map<String, AudioClip> _clips = new Map<String, AudioClip>();
 Map<String, AudioSource> _sources = new Map<String, AudioSource>();
 AudioMusic _music;

 /** Construct a new AudioManager,
  * can specify [baseURL] which is prepended to all clip URLs.
  * [baseURL] defaults to '/'
  */
 AudioManager([this.baseURL = '']) {
   _context = new AudioContext();
   _destination = _context.destination;
   _listener = _context.listener;

   _masterGain = _context.createGain();
   _musicGain = _context.createGain();
   _sourceGain = _context.createGain();

   _masterGain.connect(_destination, 0, 0);
   _musicGain.connect(_masterGain, 0, 0);
   _sourceGain.connect(_masterGain, 0, 0);

   _music = new AudioMusic._internal(this, _musicGain);
 }

 Map toJson() {
   Map map = new Map();
   map['masterVolume'] = _masterGain.gain.value;
   map['musicVolume'] = _musicGain.gain.value;
   map['sourceVolume'] = _sourceGain.gain.value;
   map['clips'] = _clips;
   map['sources'] = _sources;
   map['music'] = _music;

   return map;
 }

 void fromMap(Map map) {
   _masterGain.gain.value = map['masterVolume'];
   _musicGain.gain.value = map['musicVolume'];
   _sourceGain.gain.value = map['sourceVolume'];
   _clips = new Map<String,AudioClip>();
   map['clips'].forEach((k,v) {
     _clips[k] = new AudioClip._internal(this, k, null).fromMap(v);
     _clips[k].load();
   });
   _sources = new Map<String,AudioSource>();
   map['sources'].forEach((k,v) {
     _sources[k] = new AudioSource._internal(this, k, _sourceGain).fromMap(v);
   });
   _music.fromMap(map['music']);
 }

 /** Sample rate of the audio driver */
 num get sampleRate => _context.sampleRate;

 /** Get the music volume. */
 num get musicVolume => _musicGain.gain.value;
 /** Set the music volume. */
 void set musicVolume(num mv) {
   _musicGain.gain.value = mv;
 }

 /** Get the master volume. */
 num get masterVolume => _masterGain.gain.value;
 /** Set the master volume. */
 void set masterVolume(num mv) {
   mute = false;
   _masterGain.gain.value = mv;
 }

 /** Get the sources volume */
 num get sourceVolume => _sourceGain.gain.value;
 /** Set the sources volume */
 void set sourceVolume(num mv) {
   _sourceGain.gain.value = mv;
 }

 num _mutedVolume;
 /** Is the master volume muted? */
 bool get mute => _mutedVolume != null;

 /** Control the master mute */
 void set mute(bool b) {
   if (b) {
    if (_mutedVolume != null) {
      // Double mute.
      return;
    }
    _mutedVolume = _masterGain.gain.value;
    _masterGain.gain.value = 0;
   } else {
     if (_mutedVolume == null) {
       // Double unmute.
       return;
     }
     _masterGain.gain.value = _mutedVolume;
     _mutedVolume = null;
   }
 }

 /** Pause both music and source based sounds. */
 void pauseAll() {
   pauseSources();
   pauseMusic();
 }

 /** Resume both music and source based sounds. */
 void resumeAll() {
   resumeSources();
   resumeMusic();
 }

 bool _musicPaused = false;
 /** Pause music sounds */
 void pauseMusic() {
   _music.pause = true;
   _musicPaused = true;
 }
 /** Resume music sounds */
 void resumeMusic() {
   _music.pause = false;
   _musicPaused = false;
 }

 bool _sourcesPaused = false;
 /** Pause source base sounds. */
 void pauseSources() {
   _sources.forEach((k,v) {
     v.pause = true;
   });
   _sourcesPaused = true;
 }

 /** Resume source base sounds. */
 void resumeSources() {
   _sources.forEach((k,v) {
     v.pause = false;
   });
   _sourcesPaused = false;
 }

 /** Find the audio clip with [name] */
 AudioClip findClip(String name) {
   return _clips[name];
 }

 /** Find the audio source with [name] */
 AudioSource findSource(String name) {
   return _sources[name];
 }

 /** Get the [AudioMusic] singleton. */
 AudioMusic get music => _music;

 /** Create an [AudioClip] with [name]. */
 AudioClip makeClip(String name, String url) {
   AudioClip clip = _clips[name];
   if (clip != null) {
     return clip;
   }
   clip = new AudioClip._internal(this, name, url);
   _clips[name] = clip;
   return clip;
 }

 /** Batch create many clips. */
 List<AudioClip> makeClips(List<String> names, List<String> urls) {
   if (names == null || urls == null ||
       (names.length != urls.length)) {
     throw new ArgumentError('Invalid arguments.');
   }
   List<AudioClip> clips = new List<AudioClip>();
   for (int i = 0; i < names.length; i++) {
     clips.add(makeClip(names[i], urls[i]));
   }
 }

 AudioClip removeClip(String name) => _clips.remove(name);

 /** Batch load all clips not marked as ready to play.
  * Returns a single Future which will complete once all the clips have loaded.
  */
 Future<List<AudioClip>> loadClips() {
   List<Future<AudioClip>> loaded = new List<Future<AudioClip>>();
   _clips.forEach((name, clip) {
     if (clip.isReadyToPlay == false) {
       loaded.add(clip.load());
     }
   });
   return Future.wait(loaded);
 }

 /** Create an [AudioSource] and assign it [name] */
 AudioSource makeSource(String name) {
   AudioSource source = _sources[name];
   if (source != null) {
     return source;
   }
   source = new AudioSource._internal(this, name, _sourceGain);
   _sources[name] = source;
   return source;
 }

 /** Play [clipName] from [sourceName]. */
 AudioSound playClipFromSource(String sourceName, String clipName, [bool looped=false]) {
   return playClipFromSourceIn(0.0, sourceName, clipName, looped);
 }

 /** Play [clipName] from [sourceName] in [delay] seconds. */
 AudioSound playClipFromSourceIn(num delay, String sourceName, String clipName, [bool looped=false]) {
   AudioSource source = _sources[sourceName];
   if (source == null) {
     // TODO(johnmccutchan): Determine error route.
     print('Could not find source $sourceName');
     return null;
   }
   AudioClip clip = _clips[clipName];
   if (clip == null) {
     // TODO(johnmccutchan): Determine error route.
     print('Could not find clip $clipName');
     return null;
   }
   if (looped) {
     return source.playLoopedIn(delay, clip);
   } else {
     return source.playOnceIn(delay, clip);
   }
 }

 /** Stop all sounds originating from [sourceName] */
 void stopSource(String sourceName) {
   AudioSource source = _sources[sourceName];
   if (source == null) {
     // TODO(johnmccutchan): Determine error route.
     print('Could not find source $sourceName');
     return;
   }
   source.stop();
 }

 /** Pause all sounds originating from [sourceName] */
 void pauseSource(String sourceName) {
   AudioSource source = _sources[sourceName];
   if (source == null) {
     // TODO(johnmccutchan): Determine error route.
     print('Could not find source $sourceName');
     return;
   }
   source.pause = true;
 }

 /** Resume all sounds originating from [sourceName] */
 void resumeSource(String sourceName) {
   AudioSource source = _sources[sourceName];
   if (source == null) {
     // TODO(johnmccutchan): Determine error route.
     print('Could not find source $sourceName');
     return;
   }
   source.pause = false;
 }

 num get dopplerFactor => _listener.dopplerFactor;

 void set dopplerFactor(num df) {
   _listener.dopplerFactor = df;
 }

 num get speedOfSound => _listener.speedOfSound;

 void set speedOfSound(num sos) {
   _listener.speedOfSound = sos;
 }

 void setPosition(num x, num y, num z) {
   _listener.setPosition(x, y, z);
 }

 void setVelocity(num x, num y, num z) {
   _listener.setVelocity(x, y, z);
 }
}