From 8b74c4e1a443881ab137b151d22dbed2117c55c8 Mon Sep 17 00:00:00 2001
From: Vadim <44135514+vodemn@users.noreply.github.com>
Date: Fri, 19 May 2023 11:12:10 +0200
Subject: [PATCH] ML-72 buildPreview() was called on a disposed
 CameraController (#73)

* added `DeinitializeEvent`

* typo
---
 .../bloc_container_camera.dart                | 41 ++++++++++---------
 .../event_container_camera.dart               |  4 +-
 2 files changed, 24 insertions(+), 21 deletions(-)

diff --git a/lib/screens/metering/components/camera_container/bloc_container_camera.dart b/lib/screens/metering/components/camera_container/bloc_container_camera.dart
index da1c5ce..d70e6a2 100644
--- a/lib/screens/metering/components/camera_container/bloc_container_camera.dart
+++ b/lib/screens/metering/components/camera_container/bloc_container_camera.dart
@@ -23,8 +23,7 @@ import 'package:lightmeter/utils/log_2.dart';
 class CameraContainerBloc extends EvSourceBlocBase<CameraContainerEvent, CameraContainerState> {
   final MeteringInteractor _meteringInteractor;
   late final _WidgetsBindingObserver _observer;
-  CameraController? _cameraController;
-  CameraController? get cameraController => _cameraController;
+  late CameraController _cameraController;
 
   static const _maxZoom = 7.0;
   RangeValues? _zoomRange;
@@ -50,6 +49,7 @@ class CameraContainerBloc extends EvSourceBlocBase<CameraContainerEvent, CameraC
     on<RequestPermissionEvent>(_onRequestPermission);
     on<OpenAppSettingsEvent>(_onOpenAppSettings);
     on<InitializeEvent>(_onInitialize);
+    on<DeinitializeEvent>(_onDeinitialize);
     on<ZoomChangedEvent>(_onZoomChanged);
     on<ExposureOffsetChangedEvent>(_onExposureOffsetChanged);
     on<ExposureOffsetResetEvent>(_onExposureOffsetResetEvent);
@@ -60,7 +60,7 @@ class CameraContainerBloc extends EvSourceBlocBase<CameraContainerEvent, CameraC
   @override
   Future<void> close() async {
     WidgetsBinding.instance.removeObserver(_observer);
-    unawaited(_cameraController?.dispose());
+    unawaited(_cameraController.dispose());
     communicationBloc.add(communication_event.MeteringEndedEvent(_ev100));
     return super.close();
   }
@@ -118,30 +118,30 @@ class CameraContainerBloc extends EvSourceBlocBase<CameraContainerEvent, CameraC
         enableAudio: false,
       );
 
-      await _cameraController!.initialize();
-      await _cameraController!.setFlashMode(FlashMode.off);
+      await _cameraController.initialize();
+      await _cameraController.setFlashMode(FlashMode.off);
 
       _zoomRange = await Future.wait<double>([
-        _cameraController!.getMinZoomLevel(),
-        _cameraController!.getMaxZoomLevel(),
+        _cameraController.getMinZoomLevel(),
+        _cameraController.getMaxZoomLevel(),
       ]).then((levels) => RangeValues(levels[0], math.min(_maxZoom, levels[1])));
       _currentZoom = _zoomRange!.start;
 
       _exposureOffsetRange = await Future.wait<double>([
-        _cameraController!.getMinExposureOffset(),
-        _cameraController!.getMaxExposureOffset(),
+        _cameraController.getMinExposureOffset(),
+        _cameraController.getMaxExposureOffset(),
       ]).then(
         (levels) => RangeValues(
           math.max(_exposureMaxRange.start, levels[0]),
           math.min(_exposureMaxRange.end, levels[1]),
         ),
       );
-      await _cameraController!.getExposureOffsetStepSize().then((value) {
+      await _cameraController.getExposureOffsetStepSize().then((value) {
         _exposureStep = value == 0 ? 0.1 : value;
       });
       _currentExposureOffset = 0.0;
 
-      emit(CameraInitializedState(_cameraController!));
+      emit(CameraInitializedState(_cameraController));
 
       _emitActiveState(emit);
     } catch (e) {
@@ -149,14 +149,19 @@ class CameraContainerBloc extends EvSourceBlocBase<CameraContainerEvent, CameraC
     }
   }
 
+  Future<void> _onDeinitialize(DeinitializeEvent _, Emitter emit) async {
+    emit(const CameraLoadingState());
+    unawaited(_cameraController.dispose());
+  }
+
   Future<void> _onZoomChanged(ZoomChangedEvent event, Emitter emit) async {
-    _cameraController!.setZoomLevel(event.value);
+    _cameraController.setZoomLevel(event.value);
     _currentZoom = event.value;
     _emitActiveState(emit);
   }
 
   Future<void> _onExposureOffsetChanged(ExposureOffsetChangedEvent event, Emitter emit) async {
-    _cameraController!.setExposureOffset(event.value);
+    _cameraController.setExposureOffset(event.value);
     _currentExposureOffset = event.value;
     _emitActiveState(emit);
   }
@@ -178,13 +183,12 @@ class CameraContainerBloc extends EvSourceBlocBase<CameraContainerEvent, CameraC
     );
   }
 
-  bool get _canTakePhoto => !(_cameraController == null ||
-      !_cameraController!.value.isInitialized ||
-      _cameraController!.value.isTakingPicture);
+  bool get _canTakePhoto =>
+      !(!_cameraController.value.isInitialized || _cameraController.value.isTakingPicture);
 
   Future<double?> _takePhoto() async {
     try {
-      final file = await _cameraController!.takePicture();
+      final file = await _cameraController.takePicture();
       final Uint8List bytes = await file.readAsBytes();
       Directory(file.path).deleteSync(recursive: true);
 
@@ -213,8 +217,7 @@ class CameraContainerBloc extends EvSourceBlocBase<CameraContainerEvent, CameraC
         add(const InitializeEvent());
       case AppLifecycleState.paused:
       case AppLifecycleState.detached:
-        _cameraController?.dispose();
-        _cameraController = null;
+        add(const DeinitializeEvent());
       default:
     }
   }
diff --git a/lib/screens/metering/components/camera_container/event_container_camera.dart b/lib/screens/metering/components/camera_container/event_container_camera.dart
index e90aa0a..7f358b7 100644
--- a/lib/screens/metering/components/camera_container/event_container_camera.dart
+++ b/lib/screens/metering/components/camera_container/event_container_camera.dart
@@ -14,8 +14,8 @@ class InitializeEvent extends CameraContainerEvent {
   const InitializeEvent();
 }
 
-class ReinitializeEvent extends CameraContainerEvent {
-  const ReinitializeEvent();
+class DeinitializeEvent extends CameraContainerEvent {
+  const DeinitializeEvent();
 }
 
 class ZoomChangedEvent extends CameraContainerEvent {