indicate EV value error

lib/data/haptics_service.dart

@@ -7,9 +7,11 @@ class HapticsService {
 
   Future<void> responseVibration() async => _tryVibrate(duration: 50, amplitude: 128);
 
+  Future<void> errorVibration() async => _tryVibrate(duration: 100, amplitude: 128);
+
   Future<void> _tryVibrate({required int duration, required int amplitude}) async {
     if (await _canVibrate()) {
-      Vibration.vibrate(
+      await Vibration.vibrate(
         duration: duration,
         amplitude: amplitude,
       );

lib/interactors/metering_interactor.dart

@@ -33,13 +33,18 @@ class MeteringInteractor {
   bool get isHapticsEnabled => _userPreferencesService.haptics;
 
   /// Executes vibration if haptics are enabled in settings
-  void quickVibration() {
+  Future<void> quickVibration() async {
-    if (_userPreferencesService.haptics) _hapticsService.quickVibration();
+    if (_userPreferencesService.haptics) await _hapticsService.quickVibration();
   }
 
   /// Executes vibration if haptics are enabled in settings
-  void responseVibration() {
+  Future<void> responseVibration() async {
-    if (_userPreferencesService.haptics) _hapticsService.responseVibration();
+    if (_userPreferencesService.haptics) await _hapticsService.responseVibration();
+  }
+
+  /// Executes vibration if haptics are enabled in settings
+  Future<void> errorVibration() async {
+    if (_userPreferencesService.haptics) await _hapticsService.errorVibration();
   }
 
   Future<bool> checkCameraPermission() async {

lib/screens/metering/bloc_metering.dart

@@ -32,7 +32,7 @@ class MeteringBloc extends Bloc<MeteringEvent, MeteringState> {
   late IsoValue _iso = _userPreferencesService.iso;
   late NdValue _nd = _userPreferencesService.ndFilter;
   late Film _film = _userPreferencesService.film;
-  double _ev100 = 0.0;
+  double? _ev100 = 0.0;
   bool _isMeteringInProgress = false;
 
   MeteringBloc(
@@ -42,12 +42,13 @@ class MeteringBloc extends Bloc<MeteringEvent, MeteringState> {
     this._equipmentProfileData,
     this.stopType,
   ) : super(
-          MeteringEndedState(
+          MeteringDataState(
             ev: 0.0,
             film: _userPreferencesService.film,
             iso: _userPreferencesService.iso,
             nd: _userPreferencesService.ndFilter,
             exposurePairs: const [],
+            continuousMetering: false,
           ),
         ) {
     _communicationSubscription = _communicationBloc.stream
@@ -62,6 +63,7 @@ class MeteringBloc extends Bloc<MeteringEvent, MeteringState> {
     on<NdChangedEvent>(_onNdChanged);
     on<MeasureEvent>(_onMeasure);
     on<MeasuredEvent>(_onMeasured);
+    on<MeasureErrorEvent>(_onMeasureError);
   }
 
   @override
@@ -73,13 +75,13 @@ class MeteringBloc extends Bloc<MeteringEvent, MeteringState> {
   void _onCommunicationState(communication_states.ScreenState communicationState) {
     if (communicationState is communication_states.MeasuredState) {
       _isMeteringInProgress = communicationState is communication_states.MeteringInProgressState;
-      add(MeasuredEvent(communicationState.ev100));
+      _handleEv100(communicationState.ev100);
     }
   }
 
   void _onStopTypeChanged(StopTypeChangedEvent event, Emitter emit) {
     stopType = event.stopType;
-    _emitMeasuredState(emit);
+    _updateMeasurements();
   }
 
   void _onEquipmentProfileChanged(EquipmentProfileChangedEvent event, Emitter emit) {
@@ -98,7 +100,7 @@ class MeteringBloc extends Bloc<MeteringEvent, MeteringState> {
       _nd = event.equipmentProfileData.ndValues.first;
     }
 
-    _emitMeasuredState(emit);
+    _updateMeasurements();
   }
 
   void _onFilmChanged(FilmChangedEvent event, Emitter emit) {
@@ -111,7 +113,7 @@ class MeteringBloc extends Bloc<MeteringEvent, MeteringState> {
     }
     _film = event.data;
     _userPreferencesService.film = event.data;
-    _emitMeasuredState(emit);
+    _updateMeasurements();
   }
 
   void _onIsoChanged(IsoChangedEvent event, Emitter emit) {
@@ -120,47 +122,57 @@ class MeteringBloc extends Bloc<MeteringEvent, MeteringState> {
     }
     _userPreferencesService.iso = event.isoValue;
     _iso = event.isoValue;
-    _emitMeasuredState(emit);
+    _updateMeasurements();
   }
 
   void _onNdChanged(NdChangedEvent event, Emitter emit) {
     _userPreferencesService.ndFilter = event.ndValue;
     _nd = event.ndValue;
-    _emitMeasuredState(emit);
+    _updateMeasurements();
   }
 
-  void _onMeasure(_, Emitter emit) {
+  void _onMeasure(MeasureEvent _, Emitter emit) {
     _meteringInteractor.quickVibration();
     _communicationBloc.add(const communication_events.MeasureEvent());
     _isMeteringInProgress = true;
     emit(const LoadingState());
   }
 
+  void _updateMeasurements() => _handleEv100(_ev100);
+
+  void _handleEv100(double? ev100) {
+    if (ev100 == null || ev100.isNaN || ev100.isInfinite) {
+      add(const MeasureErrorEvent());
+    } else {
+      add(MeasuredEvent(ev100));
+    }
+  }
+
   void _onMeasured(MeasuredEvent event, Emitter emit) {
     _meteringInteractor.responseVibration();
     _ev100 = event.ev100;
-    _emitMeasuredState(emit);
+    final ev = event.ev100 + log2(_iso.value / 100) - _nd.stopReduction;
+    emit(MeteringDataState(
+      ev: ev,
+      film: _film,
+      iso: _iso,
+      nd: _nd,
+      exposurePairs: _buildExposureValues(ev),
+      continuousMetering: _isMeteringInProgress,
+    ));
   }
 
-  void _emitMeasuredState(Emitter emit) {
+  void _onMeasureError(MeasureErrorEvent _, Emitter emit) {
-    final ev = _ev100 + log2(_iso.value / 100) - _nd.stopReduction;
+    _meteringInteractor.errorVibration();
-    emit(
+    _ev100 = null;
-      _isMeteringInProgress
+    emit(MeteringDataState(
-          ? MeteringInProgressState(
+      ev: null,
-              ev: ev,
+      film: _film,
-              film: _film,
+      iso: _iso,
-              iso: _iso,
+      nd: _nd,
-              nd: _nd,
+      exposurePairs: const [],
-              exposurePairs: _buildExposureValues(ev),
+      continuousMetering: _isMeteringInProgress,
-            )
+    ));
-          : MeteringEndedState(
-              ev: ev,
-              film: _film,
-              iso: _iso,
-              nd: _nd,
-              exposurePairs: _buildExposureValues(ev),
-            ),
-    );
   }
 
   List<ExposurePair> _buildExposureValues(double ev) {

lib/screens/metering/communication/event_communication_metering.dart

@@ -15,7 +15,7 @@ class MeasureEvent extends ScreenEvent {
 }
 
 abstract class MeasuredEvent extends SourceEvent {
-  final double ev100;
+  final double? ev100;
 
   const MeasuredEvent(this.ev100);
 }

lib/screens/metering/communication/state_communication_metering.dart

@@ -19,7 +19,7 @@ class MeasureState extends SourceState {
 }
 
 abstract class MeasuredState extends ScreenState {
-  final double ev100;
+  final double? ev100;
 
   const MeasuredState(this.ev100);
 }

lib/screens/metering/components/bottom_controls/components/measure_button/widget_button_measure.dart

@@ -6,11 +6,13 @@ import 'package:lightmeter/screens/shared/filled_circle/widget_circle_filled.dar
 class MeteringMeasureButton extends StatefulWidget {
   final double? ev;
   final bool isMetering;
+  final bool hasError;
   final VoidCallback onTap;
 
   const MeteringMeasureButton({
     required this.ev,
     required this.isMetering,
+    required this.hasError,
     required this.onTap,
     super.key,
   });
@@ -63,7 +65,12 @@ class _MeteringMeasureButtonState extends State<MeteringMeasureButton> {
                     color: Theme.of(context).colorScheme.onSurface,
                     size: Dimens.grid72 - Dimens.grid8,
                     child: Center(
-                      child: widget.ev != null ? _EvValueText(ev: widget.ev!) : null,
+                      child: widget.hasError
+                          ? Icon(
+                              Icons.error,
+                              color: Theme.of(context).colorScheme.surface,
+                            )
+                          : (widget.ev != null ? _EvValueText(ev: widget.ev!) : null),
                     ),
                   ),
                 ),

lib/screens/metering/components/bottom_controls/provider_bottom_controls.dart

@@ -6,6 +6,7 @@ import 'package:lightmeter/screens/metering/components/bottom_controls/widget_bo
 class MeteringBottomControlsProvider extends StatelessWidget {
   final double? ev;
   final bool isMetering;
+  final bool hasError;
   final VoidCallback? onSwitchEvSourceType;
   final VoidCallback onMeasure;
   final VoidCallback onSettings;
@@ -13,6 +14,7 @@ class MeteringBottomControlsProvider extends StatelessWidget {
   const MeteringBottomControlsProvider({
     required this.ev,
     required this.isMetering,
+    required this.hasError,
     required this.onSwitchEvSourceType,
     required this.onMeasure,
     required this.onSettings,
@@ -36,6 +38,7 @@ class MeteringBottomControlsProvider extends StatelessWidget {
       child: MeteringBottomControls(
         ev: ev,
         isMetering: isMetering,
+        hasError: hasError,
         onSwitchEvSourceType: onSwitchEvSourceType,
         onMeasure: onMeasure,
         onSettings: onSettings,

lib/screens/metering/components/bottom_controls/widget_bottom_controls.dart

@@ -7,6 +7,7 @@ import 'package:provider/provider.dart';
 class MeteringBottomControls extends StatelessWidget {
   final double? ev;
   final bool isMetering;
+  final bool hasError;
   final VoidCallback? onSwitchEvSourceType;
   final VoidCallback onMeasure;
   final VoidCallback onSettings;
@@ -14,6 +15,7 @@ class MeteringBottomControls extends StatelessWidget {
   const MeteringBottomControls({
     required this.ev,
     required this.isMetering,
+    required this.hasError,
     required this.onSwitchEvSourceType,
     required this.onMeasure,
     required this.onSettings,
@@ -54,6 +56,7 @@ class MeteringBottomControls extends StatelessWidget {
                 MeteringMeasureButton(
                   ev: ev,
                   isMetering: isMetering,
+                  hasError: hasError,
                   onTap: onMeasure,
                 ),
                 Expanded(

lib/screens/metering/event_metering.dart

@@ -44,3 +44,7 @@ class MeasuredEvent extends MeteringEvent {
 
   const MeasuredEvent(this.ev100);
 }
+
+class MeasureErrorEvent extends MeteringEvent {
+  const MeasureErrorEvent();
+}

lib/screens/metering/screen_metering.dart

@@ -63,7 +63,9 @@ 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 MeteringInProgressState,
+              isMetering:
+                  state is LoadingState || state is MeteringDataState && state.continuousMetering,
+              hasError: state is MeteringDataState && state.hasError,
               onSwitchEvSourceType: context.read<Environment>().hasLightSensor
                   ? EvSourceTypeProvider.of(context).toggleType
                   : null,

lib/screens/metering/state_metering.dart

@@ -12,12 +12,13 @@ class LoadingState extends MeteringState {
   const LoadingState();
 }
 
-abstract class MeteringDataState extends MeteringState {
+class MeteringDataState extends MeteringState {
-  final double ev;
+  final double? ev;
   final Film film;
   final IsoValue iso;
   final NdValue nd;
   final List<ExposurePair> exposurePairs;
+  final bool continuousMetering;
 
   const MeteringDataState({
     required this.ev,
@@ -25,28 +26,10 @@ abstract class MeteringDataState extends MeteringState {
     required this.iso,
     required this.nd,
     required this.exposurePairs,
+    required this.continuousMetering,
   });
 
   ExposurePair? get fastest => exposurePairs.isEmpty ? null : exposurePairs.first;
   ExposurePair? get slowest => exposurePairs.isEmpty ? null : exposurePairs.last;
-}
+  bool get hasError => ev == null;
-
-class MeteringInProgressState extends MeteringDataState {
-  const MeteringInProgressState({
-    required super.ev,
-    required super.film,
-    required super.iso,
-    required super.nd,
-    required super.exposurePairs,
-  });
-}
-
-class MeteringEndedState extends MeteringDataState {
-  const MeteringEndedState({
-    required super.ev,
-    required super.film,
-    required super.iso,
-    required super.nd,
-    required super.exposurePairs,
-  });
 }