Initial commit

lib/backend.dart

@@ -0,0 +1,49 @@
+import 'package:flutter/widgets.dart';
+import 'package:rxdart/rxdart.dart';
+
+class Backend extends InheritedWidget {
+  static Backend of(BuildContext context) =>
+      context.inheritFromWidgetOfExactType(Backend);
+
+  final Widget child;
+
+  final playerActive = BehaviorSubject.seeded(false);
+  final playing = BehaviorSubject.seeded(false);
+  final position = BehaviorSubject.seeded(0.0);
+
+  Backend({
+    @required this.child,
+  }) : super(child: child);
+
+  void startPlayer() {
+    playerActive.add(true);
+  }
+
+  void playPause() {
+    playing.add(!playing.value);
+    if (playing.value) {
+      simulatePlay();
+    }
+  }
+
+  void seekTo(double pos) {
+    position.add(pos);
+  }
+
+  Future<void> simulatePlay() async {
+    while (playing.value) {
+      await Future.delayed(Duration(milliseconds: 200));
+      if (position.value >= 0.99) {
+        position.add(0.0);
+      } else {
+        position.add(position.value + 0.01);
+      }
+    }
+  }
+
+  @override
+  bool updateShouldNotify(Backend old) =>
+      playerActive != old.playerActive ||
+      playing != old.playing ||
+      position != old.position;
+}