MeteringScreenLayout = InheritedModelBase<MeteringScreenLayoutFeature, bool>

lib/providers/metering_screen_layout_provider.dart

@@ -1,8 +1,11 @@
 import 'package:flutter/material.dart';
 import 'package:lightmeter/data/models/metering_screen_layout_config.dart';
 import 'package:lightmeter/data/shared_prefs_service.dart';
+import 'package:lightmeter/utils/inherited_generics.dart';
 import 'package:provider/provider.dart';
 
+typedef MeteringScreenLayout = InheritedModelBase<MeteringScreenLayoutFeature, bool>;
+
 class MeteringScreenLayoutProvider extends StatefulWidget {
   final Widget child;
 
@@ -22,8 +25,8 @@ class MeteringScreenLayoutProviderState extends State<MeteringScreenLayoutProvid
 
   @override
   Widget build(BuildContext context) {
-    return MeteringScreenLayout(
-      config: MeteringScreenLayoutConfig.from(_config),
+    return InheritedModelBase<MeteringScreenLayoutFeature, bool>(
+      data: MeteringScreenLayoutConfig.from(_config),
       child: widget.child,
     );
   }
@@ -41,42 +44,3 @@ class MeteringScreenLayoutProviderState extends State<MeteringScreenLayoutProvid
     context.read<UserPreferencesService>().meteringScreenLayout = _config;
   }
 }
-
-class MeteringScreenLayout extends InheritedModel<MeteringScreenLayoutFeature> {
-  final MeteringScreenLayoutConfig config;
-
-  const MeteringScreenLayout({
-    required this.config,
-    required super.child,
-    super.key,
-  });
-
-  static MeteringScreenLayoutConfig of(BuildContext context, {bool listen = true}) {
-    if (listen) {
-      return context.dependOnInheritedWidgetOfExactType<MeteringScreenLayout>()!.config;
-    } else {
-      return context.findAncestorWidgetOfExactType<MeteringScreenLayout>()!.config;
-    }
-  }
-
-  static bool featureStatusOf(BuildContext context, MeteringScreenLayoutFeature feature) {
-    return InheritedModel.inheritFrom<MeteringScreenLayout>(context, aspect: feature)!
-        .config[feature]!;
-  }
-
-  @override
-  bool updateShouldNotify(MeteringScreenLayout oldWidget) => true;
-
-  @override
-  bool updateShouldNotifyDependent(
-    MeteringScreenLayout oldWidget,
-    Set<MeteringScreenLayoutFeature> dependencies,
-  ) {
-    for (final dependecy in dependencies) {
-      if (oldWidget.config[dependecy] != config[dependecy]) {
-        return true;
-      }
-    }
-    return false;
-  }
-}

lib/screens/metering/components/camera_container/widget_container_camera.dart

@@ -56,14 +56,14 @@ class CameraContainer extends StatelessWidget {
       topBarOverflow += Dimens.readingContainerSingleValueHeight;
       topBarOverflow += Dimens.paddingS;
     }
-    if (MeteringScreenLayout.featureStatusOf(
+    if (MeteringScreenLayout.featureOf(
       context,
       MeteringScreenLayoutFeature.extremeExposurePairs,
     )) {
       topBarOverflow += Dimens.readingContainerDoubleValueHeight;
       topBarOverflow += Dimens.paddingS;
     }
-    if (MeteringScreenLayout.featureStatusOf(
+    if (MeteringScreenLayout.featureOf(
       context,
       MeteringScreenLayoutFeature.filmPicker,
     )) {

lib/screens/metering/components/shared/readings_container/widget_container_readings.dart

@@ -42,7 +42,7 @@ class ReadingsContainer extends StatelessWidget {
           const _EquipmentProfilePicker(),
           const _InnerPadding(),
         ],
-        if (MeteringScreenLayout.featureStatusOf(
+        if (MeteringScreenLayout.featureOf(
           context,
           MeteringScreenLayoutFeature.extremeExposurePairs,
         )) ...[
@@ -60,7 +60,7 @@ class ReadingsContainer extends StatelessWidget {
           ),
           const _InnerPadding(),
         ],
-        if (MeteringScreenLayout.featureStatusOf(
+        if (MeteringScreenLayout.featureOf(
           context,
           MeteringScreenLayoutFeature.filmPicker,
         )) ...[

lib/screens/metering/screen_metering.dart

@@ -7,7 +7,6 @@ import 'package:lightmeter/data/models/metering_screen_layout_config.dart';
 import 'package:lightmeter/environment.dart';
 import 'package:lightmeter/providers/equipment_profile_provider.dart';
 import 'package:lightmeter/providers/ev_source_type_provider.dart';
-import 'package:lightmeter/providers/metering_screen_layout_provider.dart';
 import 'package:lightmeter/screens/metering/bloc_metering.dart';
 import 'package:lightmeter/screens/metering/components/bottom_controls/provider_bottom_controls.dart';
 import 'package:lightmeter/screens/metering/components/camera_container/provider_container_camera.dart';
@@ -31,17 +30,11 @@ class _MeteringScreenState extends State<MeteringScreen> {
   void didChangeDependencies() {
     super.didChangeDependencies();
     _bloc.add(EquipmentProfileChangedEvent(EquipmentProfile.of(context)));
-    if (!MeteringScreenLayout.featureStatusOf(context, MeteringScreenLayoutFeature.filmPicker)) {
-      _bloc.add(const FilmChangedEvent(Film.other()));
-    }
   }
 
   @override
   Widget build(BuildContext context) {
-    return InheritedWidgetListener<StopType>(
-      onDidChangeDependencies: (value) {
-        context.read<MeteringBloc>().add(StopTypeChangedEvent(value));
-      },
+    return _InheritedListeners(
       child: Scaffold(
         backgroundColor: Theme.of(context).colorScheme.background,
         body: Column(
@@ -64,8 +57,8 @@ class _MeteringScreenState extends State<MeteringScreen> {
             BlocBuilder<MeteringBloc, MeteringState>(
               builder: (context, state) => MeteringBottomControlsProvider(
                 ev: state is MeteringDataState ? state.ev : null,
-                isMetering:
-                    state is LoadingState || state is MeteringDataState && state.continuousMetering,
+                isMetering: state is LoadingState ||
+                    state is MeteringDataState && state.continuousMetering,
                 hasError: state is MeteringDataState && state.hasError,
                 onSwitchEvSourceType: context.read<Environment>().hasLightSensor
                     ? EvSourceTypeProvider.of(context).toggleType
@@ -81,6 +74,28 @@ class _MeteringScreenState extends State<MeteringScreen> {
   }
 }
 
+class _InheritedListeners extends StatelessWidget {
+  final Widget child;
+
+  const _InheritedListeners({required this.child});
+
+  @override
+  Widget build(BuildContext context) {
+    return InheritedWidgetListener<StopType>(
+      onDidChangeDependencies: (value) {
+        context.read<MeteringBloc>().add(StopTypeChangedEvent(value));
+      },
+      child: InheritedModelAspectListener<MeteringScreenLayoutFeature, bool>(
+        aspect: MeteringScreenLayoutFeature.filmPicker,
+        onDidChangeDependencies: (value) {
+          if (!value) context.read<MeteringBloc>().add(const FilmChangedEvent(Film.other()));
+        },
+        child: child,
+      ),
+    );
+  }
+}
+
 class _MeteringContainerBuidler extends StatelessWidget {
   final ExposurePair? fastest;
   final ExposurePair? slowest;

lib/utils/inherited_generics.dart

@@ -62,45 +62,6 @@ class InheritedWidgetBase<T> extends InheritedWidget {
   bool updateShouldNotify(InheritedWidgetBase<T> oldWidget) => true;
 }
 
-// class InheritedModelBase<A, R> extends InheritedModel<A> {
-//   final Map<A, R> data;
-
-//   const InheritedModelBase({
-//     required this.data,
-//     required super.child,
-//     super.key,
-//   });
-
-//   static Map<A, R> of<R, A>(BuildContext context, {bool listen = true}) {
-//     if (listen) {
-//       return context.dependOnInheritedWidgetOfExactType<InheritedModelBase<A, R>>()!.data;
-//     } else {
-//       return context.findAncestorWidgetOfExactType<InheritedModelBase<A, R>>()!.data;
-//     }
-//   }
-
-//   static R featureStatusOf<A, R>(BuildContext context, A aspect) {
-//     return InheritedModel.inheritFrom<InheritedModelBase<A, R>>(context, aspect: aspect)!
-//         .data[aspect]!;
-//   }
-
-//   @override
-//   bool updateShouldNotify(InheritedModelBase oldWidget) => true;
-
-//   @override
-//   bool updateShouldNotifyDependent(
-//     InheritedModelBase<A, R> oldWidget,
-//     Set<A> dependencies,
-//   ) {
-//     for (final dependecy in dependencies) {
-//       if (oldWidget.data[dependecy] != data[dependecy]) {
-//         return true;
-//       }
-//     }
-//     return false;
-//   }
-// }
-
 extension InheritedWidgetBaseContext on BuildContext {
   T get<T>() {
     return InheritedWidgetBase.of<T>(this, listen: false);
@@ -110,3 +71,101 @@ extension InheritedWidgetBaseContext on BuildContext {
     return InheritedWidgetBase.of<T>(this);
   }
 }
+
+/// Listening to multiple dependencies at the same time causes firing an event for all dependencies
+/// even though some of them didn't change:
+/// ```dart
+/// @override
+/// void didChangeDependencies() {
+///   super.didChangeDependencies();
+///   _bloc.add(EquipmentProfileChangedEvent(EquipmentProfile.of(context)));
+///   if (!MeteringScreenLayout.featureStatusOf(context, MeteringScreenLayoutFeature.filmPicker)) {
+///     _bloc.add(const FilmChangedEvent(Film.other()));
+///   }
+/// }
+/// ```
+/// To overcome this issue I've decided to create a generic listener,
+/// that will listen to each dependency separately.
+class InheritedModelAspectListener<A extends Object, T> extends StatefulWidget {
+  final A aspect;
+  final ValueChanged<T> onDidChangeDependencies;
+  final Widget child;
+
+  const InheritedModelAspectListener({
+    required this.aspect,
+    required this.onDidChangeDependencies,
+    required this.child,
+    super.key,
+  });
+
+  @override
+  State<InheritedModelAspectListener<A, T>> createState() =>
+      _InheritedModelAspectListenerState<A, T>();
+}
+
+class _InheritedModelAspectListenerState<A extends Object, T>
+    extends State<InheritedModelAspectListener<A, T>> {
+  @override
+  void didChangeDependencies() {
+    super.didChangeDependencies();
+    widget.onDidChangeDependencies(context.listenModelFeature<A, T>(widget.aspect));
+  }
+
+  @override
+  Widget build(BuildContext context) {
+    return widget.child;
+  }
+}
+
+class InheritedModelBase<A, T> extends InheritedModel<A> {
+  final Map<A, T> data;
+
+  const InheritedModelBase({
+    required this.data,
+    required super.child,
+    super.key,
+  });
+
+  static Map<A, T> of<A, T>(BuildContext context, {bool listen = true}) {
+    if (listen) {
+      return context.dependOnInheritedWidgetOfExactType<InheritedModelBase<A, T>>()!.data;
+    } else {
+      return context.findAncestorWidgetOfExactType<InheritedModelBase<A, T>>()!.data;
+    }
+  }
+
+  static T featureOf<A extends Object, T>(BuildContext context, A aspect) {
+    return InheritedModel.inheritFrom<InheritedModelBase<A, T>>(context, aspect: aspect)!
+        .data[aspect]!;
+  }
+
+  @override
+  bool updateShouldNotify(InheritedModelBase oldWidget) => true;
+
+  @override
+  bool updateShouldNotifyDependent(
+    InheritedModelBase<A, T> oldWidget,
+    Set<A> dependencies,
+  ) {
+    for (final dependecy in dependencies) {
+      if (oldWidget.data[dependecy] != data[dependecy]) {
+        return true;
+      }
+    }
+    return false;
+  }
+}
+
+extension InheritedModelBaseContext on BuildContext {
+  Map<A, T> getModel<A, T>() {
+    return InheritedModelBase.of<A, T>(this, listen: false);
+  }
+
+  Map<A, T> listenModel<A, T>() {
+    return InheritedModelBase.of<A, T>(this);
+  }
+
+  T listenModelFeature<A extends Object, T>(A aspect) {
+    return InheritedModelBase.featureOf<A, T>(this, aspect);
+  }
+}