From 2e3335e3745eed478ec3f3583207fdd3ff68d6ca Mon Sep 17 00:00:00 2001
From: Vadim <44135514+vodemn@users.noreply.github.com>
Date: Wed, 2 Apr 2025 00:00:33 +0200
Subject: [PATCH] preserve camera controls values after controller dispose

---
 .../bloc_container_camera.dart                | 76 ++++++++++++-------
 1 file changed, 47 insertions(+), 29 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 ef6125e..4d9bd87 100644
--- a/lib/screens/metering/components/camera_container/bloc_container_camera.dart
+++ b/lib/screens/metering/components/camera_container/bloc_container_camera.dart
@@ -26,11 +26,12 @@ class CameraContainerBloc extends EvSourceBlocBase<CameraContainerEvent, CameraC
   final LightmeterAnalytics _analytics;
   late final _WidgetsBindingObserver _observer;
 
+  CameraDescription? _camera;
   CameraController? _cameraController;
 
   static const _maxZoom = 7.0;
   RangeValues? _zoomRange;
-  double _currentZoom = 0.0;
+  double _currentZoom = 1.0;
 
   static const _exposureMaxRange = RangeValues(-4, 4);
   RangeValues? _exposureOffsetRange;
@@ -116,46 +117,63 @@ class CameraContainerBloc extends EvSourceBlocBase<CameraContainerEvent, CameraC
     }
 
     try {
-      final cameras = await availableCameras();
-      if (cameras.isEmpty) {
-        emit(const CameraErrorState(CameraErrorType.noCamerasDetected));
-        return;
+      if (_camera == null) {
+        final cameras = await availableCameras();
+        if (cameras.isEmpty) {
+          emit(const CameraErrorState(CameraErrorType.noCamerasDetected));
+          return;
+        } else {
+          _camera = cameras.firstWhere(
+            (camera) => camera.lensDirection == CameraLensDirection.back,
+            orElse: () => cameras.last,
+          );
+        }
       }
+
       _cameraController = CameraController(
-        cameras.firstWhere(
-          (camera) => camera.lensDirection == CameraLensDirection.back,
-          orElse: () => cameras.last,
-        ),
+        _camera!,
         ResolutionPreset.low,
         enableAudio: false,
       );
-
       await _cameraController!.initialize();
       await _cameraController!.setFlashMode(FlashMode.off);
       await _cameraController!.lockCaptureOrientation(DeviceOrientation.portraitUp);
 
-      _zoomRange = await Future.wait<double>([
-        _cameraController!.getMinZoomLevel(),
-        _cameraController!.getMaxZoomLevel(),
-      ]).then((levels) => RangeValues(math.max(1.0, levels[0]), math.min(_maxZoom, levels[1])));
-      _currentZoom = _zoomRange!.start;
+      /// For app startup initialization this effectively isn't executed.
+      await Future.wait<void>([
+        if (_currentZoom != 1.0) _cameraController!.setZoomLevel(_currentZoom),
+        if (_currentExposureOffset != 0.0) _cameraController!.setExposureOffset(_currentExposureOffset),
+      ]);
 
-      _exposureOffsetRange = await Future.wait<double>([
-        _cameraController!.getMinExposureOffset(),
-        _cameraController!.getMaxExposureOffset(),
-      ]).then(
-        (levels) => RangeValues(
-          math.max(_exposureMaxRange.start, levels[0]),
-          math.min(_exposureMaxRange.end, levels[1]),
-        ),
-      );
-      await _cameraController!.getExposureOffsetStepSize().then((value) {
-        _exposureStep = value == 0 ? 0.1 : value;
-      });
-      _currentExposureOffset = 0.0;
+      if (_zoomRange == null) {
+        await Future.wait<double>([
+          _cameraController!.getMinZoomLevel(),
+          _cameraController!.getMaxZoomLevel(),
+        ]).then((value) {
+          _zoomRange = RangeValues(
+            math.max(1.0, value[0]),
+            math.min(_maxZoom, value[1]),
+          );
+          _currentZoom = _zoomRange!.start;
+        });
+      }
+
+      if (_exposureOffsetRange == null) {
+        await Future.wait<double>([
+          _cameraController!.getMinExposureOffset(),
+          _cameraController!.getMaxExposureOffset(),
+          _cameraController!.getExposureOffsetStepSize(),
+        ]).then((value) {
+          _exposureOffsetRange = RangeValues(
+            math.max(_exposureMaxRange.start, value[0]),
+            math.min(_exposureMaxRange.end, value[1]),
+          );
+          _currentExposureOffset = 0.0;
+          _exposureStep = value[2] == 0 ? 0.1 : value[2];
+        });
+      }
 
       emit(CameraInitializedState(_cameraController!));
-
       _emitActiveState(emit);
     } catch (e) {
       emit(const CameraErrorState(CameraErrorType.other));