m3_lightmeter/lib/screens/metering/bloc_metering.dart

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import 'dart:async';
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import 'dart:math';
import 'package:flutter_bloc/flutter_bloc.dart';
import 'package:lightmeter/data/models/photography_values/aperture_value.dart';
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import 'package:lightmeter/data/models/exposure_pair.dart';
import 'package:lightmeter/data/models/photography_values/photography_value.dart';
import 'package:lightmeter/data/models/photography_values/shutter_speed_value.dart';
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import 'package:lightmeter/data/shared_prefs_service.dart';
import 'package:lightmeter/screens/metering/communication/event_communication_metering.dart' as communication_events;
import 'package:lightmeter/screens/metering/communication/state_communication_metering.dart' as communication_states;
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import 'package:lightmeter/utils/log_2.dart';
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import 'communication/bloc_communication_metering.dart';
import 'event_metering.dart';
import 'state_metering.dart';
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class MeteringBloc extends Bloc<MeteringEvent, MeteringState> {
final MeteringCommunicationBloc _communicationBloc;
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final UserPreferencesService _userPreferencesService;
late final StreamSubscription<communication_states.ScreenState> _communicationSubscription;
List<ApertureValue> get _apertureValues => apertureValues.whereStopType(stopType);
List<ShutterSpeedValue> get _shutterSpeedValues => shutterSpeedValues.whereStopType(stopType);
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StopType stopType;
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MeteringBloc(
this._communicationBloc,
this._userPreferencesService,
this.stopType,
) : super(
MeteringState(
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iso: _userPreferencesService.iso,
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ev: 0.0,
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evCompensation: 0.0,
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nd: _userPreferencesService.ndFilter,
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exposurePairs: [],
),
) {
_communicationSubscription = _communicationBloc.stream
.where((state) => state is communication_states.ScreenState)
.map((state) => state as communication_states.ScreenState)
.listen(_onCommunicationState);
on<StopTypeChangedEvent>(_onStopTypeChanged);
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on<IsoChangedEvent>(_onIsoChanged);
on<NdChangedEvent>(_onNdChanged);
on<MeasureEvent>((_, __) => _communicationBloc.add(const communication_events.MeasureEvent()));
on<MeasuredEvent>(_onMeasured);
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add(const MeasureEvent());
}
@override
Future<void> close() async {
await _communicationSubscription.cancel();
return super.close();
}
void _onCommunicationState(communication_states.ScreenState communicationState) {
if (communicationState is communication_states.MeasuredState) {
add(MeasuredEvent(communicationState.ev100));
}
}
void _onStopTypeChanged(StopTypeChangedEvent event, Emitter emit) {
stopType = event.stopType;
emit(MeteringState(
iso: state.iso,
ev: state.ev,
evCompensation: state.evCompensation,
nd: state.nd,
exposurePairs: _buildExposureValues(state.ev),
));
}
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void _onIsoChanged(IsoChangedEvent event, Emitter emit) {
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_userPreferencesService.iso = event.isoValue;
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final ev = state.ev + log2(event.isoValue.value / state.iso.value);
emit(MeteringState(
iso: event.isoValue,
ev: ev,
evCompensation: state.evCompensation,
nd: state.nd,
exposurePairs: _buildExposureValues(ev),
));
}
void _onNdChanged(NdChangedEvent event, Emitter emit) {
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_userPreferencesService.ndFilter = event.ndValue;
final ev = state.ev - event.ndValue.stopReduction + state.nd.stopReduction;
emit(MeteringState(
iso: state.iso,
ev: ev,
evCompensation: state.evCompensation,
nd: event.ndValue,
exposurePairs: _buildExposureValues(ev),
));
}
void _onMeasured(MeasuredEvent event, Emitter emit) {
final ev = event.ev100 + log2(state.iso.value / 100);
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emit(MeteringState(
iso: state.iso,
ev: ev,
evCompensation: state.evCompensation,
nd: state.nd,
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exposurePairs: _buildExposureValues(ev),
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));
}
List<ExposurePair> _buildExposureValues(double ev) {
late final int evSteps;
switch (stopType) {
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case StopType.full:
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evSteps = ev.floor();
break;
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case StopType.half:
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evSteps = (ev / 0.5).floor();
break;
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case StopType.third:
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evSteps = (ev / 0.3).floor();
break;
}
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final evOffset = _shutterSpeedValues.indexOf(const ShutterSpeedValue(1, false, StopType.full)) - evSteps;
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late final int apertureOffset;
late final int shutterSpeedOffset;
if (evOffset >= 0) {
apertureOffset = 0;
shutterSpeedOffset = evOffset;
} else {
apertureOffset = -evOffset;
shutterSpeedOffset = 0;
}
int itemsCount = min(_apertureValues.length + shutterSpeedOffset, _shutterSpeedValues.length + apertureOffset) -
max(apertureOffset, shutterSpeedOffset);
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if (itemsCount < 0) {
return List.empty(growable: false);
}
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return List.generate(
itemsCount,
(index) => ExposurePair(
_apertureValues[index + apertureOffset],
_shutterSpeedValues[index + shutterSpeedOffset],
),
growable: false,
);
}
}