first commit

lib/services/media_state_stream.dart

@@ -0,0 +1,22 @@
+import 'package:audio_service/audio_service.dart';
+import 'package:get_it/get_it.dart';
+import 'package:rxdart/rxdart.dart';
+
+import 'music_player_background_task.dart';
+
+class MediaState {
+  final MediaItem? mediaItem;
+  final PlaybackState playbackState;
+
+  MediaState(this.mediaItem, this.playbackState);
+}
+
+/// A stream reporting the combined state of the current media item and its
+/// current position.
+Stream<MediaState> get mediaStateStream {
+  final audioHandler = GetIt.instance<MusicPlayerBackgroundTask>();
+  return Rx.combineLatest2<MediaItem?, PlaybackState, MediaState>(
+      audioHandler.mediaItem,
+      audioHandler.playbackState,
+      (mediaItem, playbackState) => MediaState(mediaItem, playbackState));
+}