Move musicus package to seperate directory

musicus/lib/screens/program.dart

@@ -0,0 +1,135 @@
+import 'dart:async';
+
+import 'package:flutter/material.dart';
+
+import '../backend.dart';
+import '../widgets/play_pause_button.dart';
+
+class ProgramScreen extends StatefulWidget {
+  @override
+  _ProgramScreenState createState() => _ProgramScreenState();
+}
+
+class _ProgramScreenState extends State<ProgramScreen> {
+  BackendState backend;
+  StreamSubscription<double> positionSubscription;
+  double position = 0.0;
+  bool seeking = false;
+
+  @override
+  void didChangeDependencies() {
+    super.didChangeDependencies();
+
+    backend = Backend.of(context);
+
+    if (positionSubscription != null) {
+      positionSubscription.cancel();
+    }
+
+    positionSubscription = backend.player.normalizedPosition.listen((pos) {
+      if (!seeking) {
+        setState(() {
+          position = pos;
+        });
+      }
+    });
+  }
+
+  @override
+  Widget build(BuildContext context) {
+    return Scaffold(
+      appBar: AppBar(
+        leading: IconButton(
+          icon: const Icon(Icons.keyboard_arrow_down),
+          onPressed: () => Navigator.pop(context),
+        ),
+        title: Text('Program'),
+      ),
+      bottomNavigationBar: BottomAppBar(
+        child: Column(
+          mainAxisSize: MainAxisSize.min,
+          children: <Widget>[
+            Slider(
+              value: position,
+              onChangeStart: (_) {
+                seeking = true;
+              },
+              onChangeEnd: (pos) {
+                seeking = false;
+                backend.player.seekTo(pos);
+              },
+              onChanged: (pos) {
+                setState(() {
+                  position = pos;
+                });
+              },
+            ),
+            Row(
+              children: <Widget>[
+                Padding(
+                  padding: const EdgeInsets.only(left: 24.0),
+                  child: StreamBuilder<Duration>(
+                    stream: backend.player.position,
+                    builder: (context, snapshot) {
+                      if (snapshot.hasData) {
+                        return DurationText(snapshot.data);
+                      } else {
+                        return Container();
+                      }
+                    },
+                  ),
+                ),
+                Spacer(),
+                IconButton(
+                  icon: const Icon(Icons.skip_previous),
+                  onPressed: () {},
+                ),
+                PlayPauseButton(),
+                IconButton(
+                  icon: const Icon(Icons.skip_next),
+                  onPressed: () {},
+                ),
+                Spacer(),
+                Padding(
+                  padding: const EdgeInsets.only(right: 20.0),
+                  child: StreamBuilder<Duration>(
+                    stream: backend.player.duration,
+                    builder: (context, snapshot) {
+                      if (snapshot.hasData) {
+                        return DurationText(snapshot.data);
+                      } else {
+                        return Container();
+                      }
+                    },
+                  ),
+                ),
+              ],
+            ),
+          ],
+        ),
+      ),
+    );
+  }
+
+  @override
+  void dispose() {
+    super.dispose();
+    positionSubscription.cancel();
+  }
+}
+
+class DurationText extends StatelessWidget {
+  final Duration duration;
+
+  DurationText(this.duration);
+
+  @override
+  Widget build(BuildContext context) {
+    final minutes = duration.inMinutes;
+    final seconds = (duration - Duration(minutes: minutes)).inSeconds;
+
+    final secondsString = seconds >= 10 ? seconds.toString() : '0$seconds';
+
+    return Text('$minutes:$secondsString');
+  }
+}