implemented MeteringScreenLayoutProvider

lib/application.dart

@@ -18,6 +18,7 @@ import 'environment.dart';
 import 'generated/l10n.dart';
 import 'providers/equipment_profile_provider.dart';
 import 'providers/ev_source_type_provider.dart';
+import 'providers/features_provider.dart';
 import 'providers/theme_provider.dart';
 import 'screens/metering/flow_metering.dart';
 import 'screens/settings/flow_settings.dart';
@@ -47,6 +48,7 @@ class Application extends StatelessWidget {
               Provider(create: (_) => PermissionsService()),
               Provider(create: (_) => const LightSensorService()),
             ],
+            child: MeteringScreenLayoutProvider(
               child: StopTypeProvider(
                 child: EquipmentProfileProvider(
                   child: EvSourceTypeProvider(
@@ -79,6 +81,7 @@ class Application extends StatelessWidget {
                   ),
                 ),
               ),
+            ),
           );
         }
         return const SizedBox();

lib/providers/features_provider.dart

@@ -0,0 +1,75 @@
+import 'package:flutter/material.dart';
+
+enum MeteringScreenLayoutFeature { extremeExposurePairs, reciprocity }
+
+class MeteringScreenLayoutProvider extends StatefulWidget {
+  final Widget child;
+
+  const MeteringScreenLayoutProvider({required this.child, super.key});
+
+  static MeteringScreenLayoutProviderState of(BuildContext context) {
+    return context.findAncestorStateOfType<MeteringScreenLayoutProviderState>()!;
+  }
+
+  @override
+  State<MeteringScreenLayoutProvider> createState() => MeteringScreenLayoutProviderState();
+}
+
+class MeteringScreenLayoutProviderState extends State<MeteringScreenLayoutProvider> {
+  final Map<MeteringScreenLayoutFeature, bool> _features = {
+    MeteringScreenLayoutFeature.extremeExposurePairs: true,
+    MeteringScreenLayoutFeature.reciprocity: true,
+  };
+
+  @override
+  Widget build(BuildContext context) {
+    return MeteringScreenLayout(
+      features: _features,
+      child: widget.child,
+    );
+  }
+
+  void setFeature(MeteringScreenLayoutFeature feature, {required bool enabled}) {
+    setState(() {
+      _features.update(
+        feature,
+        (_) => enabled,
+        ifAbsent: () => enabled,
+      );
+    });
+  }
+}
+
+class MeteringScreenLayout extends InheritedModel<MeteringScreenLayoutFeature> {
+  final Map<MeteringScreenLayoutFeature, bool> features;
+
+  const MeteringScreenLayout({
+    required this.features,
+    required super.child,
+    super.key,
+  });
+
+  static bool of(BuildContext context, MeteringScreenLayoutFeature feature, {bool listen = true}) {
+    if (listen) {
+      return context.dependOnInheritedWidgetOfExactType<MeteringScreenLayout>()!.features[feature]!;
+    } else {
+      return context.findAncestorWidgetOfExactType<MeteringScreenLayout>()!.features[feature]!;
+    }
+  }
+
+  @override
+  bool updateShouldNotify(MeteringScreenLayout oldWidget) => true;
+
+  @override
+  bool updateShouldNotifyDependent(
+    MeteringScreenLayout oldWidget,
+    Set<MeteringScreenLayoutFeature> dependencies,
+  ) {
+    for (final dependecy in dependencies) {
+      if (oldWidget.features[dependecy] != features[dependecy]) {
+        return true;
+      }
+    }
+    return false;
+  }
+}