fixed WillPopScope

lib/main.dart

@@ -1,5 +1,6 @@
 import 'package:flutter/material.dart';
 import 'package:flutter/services.dart';
+import 'package:flutter_mobx/flutter_mobx.dart';
 import 'package:provider/provider.dart';
 
 import 'presentation/pages/currently_playing.dart';
@@ -8,6 +9,7 @@ import 'presentation/pages/library_page.dart';
 import 'presentation/pages/settings_page.dart';
 import 'presentation/state/audio_store.dart';
 import 'presentation/state/music_data_store.dart';
+import 'presentation/state/navigation_store.dart';
 import 'presentation/theming.dart';
 import 'presentation/widgets/audio_service_widget.dart';
 import 'presentation/widgets/injection_widget.dart';
@@ -25,14 +27,14 @@ class MyApp extends StatelessWidget {
 
     return InjectionWidget(
       child: AudioServiceWidget(
-      child: MaterialApp(
-        title: 'mucke',
-        theme: theme(),
-        initialRoute: '/',
-        routes: {
-          '/': (context) => const RootPage(),
-          '/playing': (context) => const CurrentlyPlayingPage(),
-        },
+        child: MaterialApp(
+          title: 'mucke',
+          theme: theme(),
+          initialRoute: '/',
+          routes: {
+            '/': (context) => const RootPage(),
+            '/playing': (context) => const CurrentlyPlayingPage(),
+          },
         ),
       ),
     );
@@ -47,8 +49,6 @@ class RootPage extends StatefulWidget {
 }
 
 class _RootPageState extends State<RootPage> {
-  var navIndex = 1;
-
   final List<Widget> _pages = <Widget>[
     const HomePage(),
     const LibraryPage(
@@ -79,19 +79,19 @@ class _RootPageState extends State<RootPage> {
 
   @override
   Widget build(BuildContext context) {
+    final NavigationStore navStore = Provider.of<NavigationStore>(context);
+
     print('RootPage.build');
-    return Scaffold(
-      body: IndexedStack(
-        index: navIndex,
-        children: _pages,
-      ),
-      bottomNavigationBar: NavBar(
-        onTap: (int index) {
-          setState(() {
-            navIndex = index;
-          });
-        },
-        currentIndex: navIndex,
+    return Observer(
+      builder: (BuildContext context) => Scaffold(
+        body: IndexedStack(
+          index: navStore.navIndex,
+          children: _pages,
+        ),
+        bottomNavigationBar: NavBar(
+          onTap: (int index) => navStore.setNavIndex(index),
+          currentIndex: navStore.navIndex,
+        ),
       ),
     );
   }

lib/presentation/pages/library_page.dart

@@ -1,5 +1,7 @@
 import 'package:flutter/material.dart';
+import 'package:provider/provider.dart';
 
+import '../state/navigation_store.dart';
 import 'library_tab_container.dart';
 
 class LibraryPage extends StatelessWidget {
@@ -10,6 +12,8 @@ class LibraryPage extends StatelessWidget {
     print('LibraryPage.build');
     final GlobalKey<NavigatorState> nav = GlobalKey();
 
+    final NavigationStore navStore = Provider.of<NavigationStore>(context);
+
     return WillPopScope(
       child: Navigator(
         key: nav,
@@ -27,8 +31,10 @@ class LibraryPage extends StatelessWidget {
         },
       ),
       onWillPop: () async {
-        print('onWillPop');
-        return !await nav.currentState.maybePop();
+        if (navStore.navIndex == 1) {
+          return !await nav.currentState.maybePop();
+        }
+        return Future.value(true);
       },
     );
   }

lib/presentation/state/navigation_store.dart

@@ -0,0 +1,28 @@
+import 'package:mobx/mobx.dart';
+
+part 'navigation_store.g.dart';
+
+class NavigationStore extends _NavigationStore with _$NavigationStore {
+  NavigationStore() : super();
+}
+
+abstract class _NavigationStore with Store {
+  _NavigationStore();
+
+  bool _initialized = false;
+
+  @observable int navIndex = 1;
+
+  @action
+  Future<void> init() async {
+    if (!_initialized) {
+      print('NavigationStore.init');
+      _initialized = true;
+    }
+  }
+
+  @action
+  void setNavIndex(int i) {
+    navIndex = i;
+  }
+}

lib/presentation/state/navigation_store.g.dart

@@ -0,0 +1,54 @@
+// GENERATED CODE - DO NOT MODIFY BY HAND
+
+part of 'navigation_store.dart';
+
+// **************************************************************************
+// StoreGenerator
+// **************************************************************************
+
+// ignore_for_file: non_constant_identifier_names, unnecessary_lambdas, prefer_expression_function_bodies, lines_longer_than_80_chars, avoid_as, avoid_annotating_with_dynamic
+
+mixin _$NavigationStore on _NavigationStore, Store {
+  final _$navIndexAtom = Atom(name: '_NavigationStore.navIndex');
+
+  @override
+  int get navIndex {
+    _$navIndexAtom.context.enforceReadPolicy(_$navIndexAtom);
+    _$navIndexAtom.reportObserved();
+    return super.navIndex;
+  }
+
+  @override
+  set navIndex(int value) {
+    _$navIndexAtom.context.conditionallyRunInAction(() {
+      super.navIndex = value;
+      _$navIndexAtom.reportChanged();
+    }, _$navIndexAtom, name: '${_$navIndexAtom.name}_set');
+  }
+
+  final _$initAsyncAction = AsyncAction('init');
+
+  @override
+  Future<void> init() {
+    return _$initAsyncAction.run(() => super.init());
+  }
+
+  final _$_NavigationStoreActionController =
+      ActionController(name: '_NavigationStore');
+
+  @override
+  void setNavIndex(int i) {
+    final _$actionInfo = _$_NavigationStoreActionController.startAction();
+    try {
+      return super.setNavIndex(i);
+    } finally {
+      _$_NavigationStoreActionController.endAction(_$actionInfo);
+    }
+  }
+
+  @override
+  String toString() {
+    final string = 'navIndex: ${navIndex.toString()}';
+    return '{$string}';
+  }
+}

lib/presentation/widgets/injection_widget.dart

@@ -11,6 +11,7 @@ import '../../system/repositories/audio_repository_impl.dart';
 import '../../system/repositories/music_data_repository_impl.dart';
 import '../state/audio_store.dart';
 import '../state/music_data_store.dart';
+import '../state/navigation_store.dart';
 
 class InjectionWidget extends StatelessWidget {
   const InjectionWidget({Key key, this.child}) : super(key: key);
@@ -44,6 +45,9 @@ class InjectionWidget extends StatelessWidget {
             audioRepository: audioRepository,
           ),
         ),
+        Provider<NavigationStore>(
+          create: (BuildContext context) => NavigationStore(),
+        ),
       ],
     );
   }

pubspec.lock

@@ -28,21 +28,21 @@ packages:
       name: archive
       url: "https://pub.dartlang.org"
     source: hosted
-    version: "2.0.11"
+    version: "2.0.13"
   args:
     dependency: transitive
     description:
       name: args
       url: "https://pub.dartlang.org"
     source: hosted
-    version: "1.5.2"
+    version: "1.6.0"
   async:
     dependency: transitive
     description:
       name: async
       url: "https://pub.dartlang.org"
     source: hosted
-    version: "2.4.0"
+    version: "2.4.1"
   audio_service:
     dependency: "direct main"
     description:
@@ -56,7 +56,7 @@ packages:
       name: boolean_selector
       url: "https://pub.dartlang.org"
     source: hosted
-    version: "1.0.5"
+    version: "2.0.0"
   build:
     dependency: transitive
     description:
@@ -119,7 +119,7 @@ packages:
       name: charcode
       url: "https://pub.dartlang.org"
     source: hosted
-    version: "1.1.2"
+    version: "1.1.3"
   checked_yaml:
     dependency: transitive
     description:
@@ -147,7 +147,7 @@ packages:
       name: collection
       url: "https://pub.dartlang.org"
     source: hosted
-    version: "1.14.11"
+    version: "1.14.12"
   convert:
     dependency: transitive
     description:
@@ -161,7 +161,7 @@ packages:
       name: crypto
       url: "https://pub.dartlang.org"
     source: hosted
-    version: "2.1.3"
+    version: "2.1.4"
   csslib:
     dependency: transitive
     description:
@@ -288,7 +288,7 @@ packages:
       name: image
       url: "https://pub.dartlang.org"
     source: hosted
-    version: "2.1.4"
+    version: "2.1.12"
   io:
     dependency: transitive
     description:
@@ -512,7 +512,7 @@ packages:
       name: quiver
       url: "https://pub.dartlang.org"
     source: hosted
-    version: "2.0.5"
+    version: "2.1.3"
   recase:
     dependency: transitive
     description:
@@ -559,7 +559,7 @@ packages:
       name: source_span
       url: "https://pub.dartlang.org"
     source: hosted
-    version: "1.5.5"
+    version: "1.7.0"
   sqlparser:
     dependency: transitive
     description:
@@ -615,7 +615,7 @@ packages:
       name: test_api
       url: "https://pub.dartlang.org"
     source: hosted
-    version: "0.2.11"
+    version: "0.2.15"
   timing:
     dependency: transitive
     description:
@@ -664,7 +664,7 @@ packages:
       name: xml
       url: "https://pub.dartlang.org"
     source: hosted
-    version: "3.5.0"
+    version: "3.6.1"
   yaml:
     dependency: transitive
     description: