feat: Autopause camera after 1 min of inactivity

packages/smooth_app/lib/l10n/app_en.arb

@@ -1315,5 +1315,14 @@
     "add_photo_button_label": "Add photo",
     "@add_photo_button_label": {
         "description": "Label for the add photo button"
-    }
-}
+    },
+    "camera_paused_dialog_title": "Camera paused",
+    "camera_paused_dialog_content": "To save energy, the scanner has been automatically turned off after {min} min of inactivity",
+    "@camera_paused_dialog_content": {
+        "placeholders": {
+            "min": {}
+        }
+    },
+    "camera_paused_dialog_positive_label": "Restart camera",
+    "camera_paused_dialog_negative_label": "Stay paused"
+}

packages/smooth_app/lib/pages/scan/camera_controller.dart

@@ -93,6 +93,7 @@ class SmoothCameraController extends CameraController {
       await _pauseFlash();
       await super.pausePreview();
       _isPaused = true;
+      notifyListeners();
     }
   }
 
@@ -114,6 +115,7 @@ class SmoothCameraController extends CameraController {
     await _resumeFlash();
     await refocus();
     _isPaused = false;
+    notifyListeners();
   }
 
   Future<void> _resumeFlash() async {

packages/smooth_app/lib/pages/scan/ml_kit_scan_page.dart

@@ -1,17 +1,20 @@
 import 'dart:async';
 import 'dart:math' as math;
+import 'dart:ui';
 
 import 'package:audioplayers/audioplayers.dart';
 import 'package:camera/camera.dart';
 import 'package:flutter/foundation.dart';
 import 'package:flutter/material.dart';
 import 'package:flutter/scheduler.dart';
 import 'package:flutter/services.dart';
+import 'package:flutter_gen/gen_l10n/app_localizations.dart';
 import 'package:matomo_tracker/matomo_tracker.dart';
 import 'package:provider/provider.dart';
 import 'package:rxdart/rxdart.dart';
 import 'package:smooth_app/data_models/continuous_scan_model.dart';
 import 'package:smooth_app/data_models/user_preferences.dart';
+import 'package:smooth_app/generic_lib/dialogs/smooth_alert_dialog.dart';
 import 'package:smooth_app/helpers/camera_helper.dart';
 import 'package:smooth_app/helpers/collections_helper.dart';
 import 'package:smooth_app/pages/page_manager.dart';
@@ -52,6 +55,9 @@ class MLKitScannerPageState extends LifecycleAwareState<MLKitScannerPage>
   /// Minimal processing windows between two decodings
   static const int _processingTimeWindows = 5;
 
+  /// Period after which the camera will be paused
+  static const Duration _inactivityPeriod = Duration(minutes: 1);
+
   /// A time window is the average time decodings took
   final AverageList<int> _averageProcessingTime = AverageList<int>();
   final AudioCache _musicPlayer = AudioCache(prefix: 'assets/audio/');
@@ -84,6 +90,8 @@ class MLKitScannerPageState extends LifecycleAwareState<MLKitScannerPage>
   /// The next time this tab is visible, we will force relaunching the camera.
   bool pendingResume = false;
 
+  Timer? _inactivityTimeout;
+
   @override
   void initState() {
     super.initState();
@@ -145,13 +153,17 @@ class MLKitScannerPageState extends LifecycleAwareState<MLKitScannerPage>
     return LayoutBuilder(
       builder: (BuildContext context, BoxConstraints constraints) {
         _computePreviewScale(constraints);
+        final double blur = (_controller?.isPaused == true) ? 5.0 : 0.0;
 
         return Transform.scale(
           scale: _previewScale,
           child: Center(
             key: ValueKey<bool>(stoppingCamera),
-            child: CameraPreview(
-              _controller!,
+            child: ImageFiltered(
+              imageFilter: ImageFilter.blur(sigmaY: blur, sigmaX: blur),
+              child: CameraPreview(
+                _controller!,
+              ),
             ),
           ),
         );
@@ -290,6 +302,8 @@ class MLKitScannerPageState extends LifecycleAwareState<MLKitScannerPage>
   }
 
   Future<void> _onNewBarcodeDetected(List<String> barcodes) async {
+    bool barcodeAdded = false;
+
     for (final String barcode in barcodes) {
       if (await _model.onScan(barcode)) {
         // Both are Future methods, but it doesn't matter to wait here
@@ -303,8 +317,13 @@ class MLKitScannerPageState extends LifecycleAwareState<MLKitScannerPage>
           );
         }
         _userPreferences.setFirstScanAchieved();
+        barcodeAdded = true;
       }
     }
+
+    if (barcodeAdded) {
+      _startTimerForInactivity();
+    }
   }
 
   void _cameraListener() {
@@ -319,6 +338,8 @@ class MLKitScannerPageState extends LifecycleAwareState<MLKitScannerPage>
         // TODO(M123): Handle errors better
         debugPrint(_controller!.value.errorDescription);
       }
+    } else if (_controller?.isPaused != true) {
+      _startTimerForInactivity();
     }
   }
 
@@ -331,6 +352,7 @@ class MLKitScannerPageState extends LifecycleAwareState<MLKitScannerPage>
         _controller!.isPauseResumePreviewSupported != true) {
       await _stopImageStream(autoRestart: false);
     } else {
+      _stopTimerForInactivity();
       _streamSubscription?.pause();
       await _controller?.pausePreview();
     }
@@ -369,6 +391,7 @@ class MLKitScannerPageState extends LifecycleAwareState<MLKitScannerPage>
 
     if (_controller?.isPauseResumePreviewSupported == true) {
       await _controller?.resumePreviewIfNecessary();
+      _startTimerForInactivity();
     }
     stoppingCamera = false;
   }
@@ -380,10 +403,13 @@ class MLKitScannerPageState extends LifecycleAwareState<MLKitScannerPage>
 
     stoppingCamera = true;
 
+    _stopTimerForInactivity();
     if (_controller?.isPauseResumePreviewSupported == true) {
       await _controller?.pausePreview();
     }
 
+    await _controller?.pausePreview();
+
     _redrawScreen();
 
     _controller?.removeListener(_cameraListener);
@@ -480,6 +506,43 @@ class MLKitScannerPageState extends LifecycleAwareState<MLKitScannerPage>
 
   SmoothCameraController? get _controller => CameraHelper.controller;
 
+  /// Starts (or restarts) the timer for inactivity
+  void _startTimerForInactivity() {
+    _stopTimerForInactivity();
+
+    _inactivityTimeout = Timer(_inactivityPeriod, () async {
+      await CameraHelper.controller?.pausePreview();
+      _stopTimerForInactivity();
+
+      showDialog<bool>(
+          context: context,
+          builder: (BuildContext context) {
+            final AppLocalizations localizations = AppLocalizations.of(context);
+
+            return SmoothAlertDialog(
+              title: localizations.camera_paused_dialog_title,
+              body: Text(localizations
+                  .camera_paused_dialog_content(_inactivityPeriod.inMinutes)),
+              positiveAction: SmoothActionButton(
+                  text: localizations.camera_paused_dialog_positive_label,
+                  onPressed: () async {
+                    Navigator.of(context).pop();
+                    CameraHelper.controller?.resumePreviewIfNecessary();
+                  }),
+              negativeAction: SmoothActionButton(
+                  text: localizations.camera_paused_dialog_negative_label,
+                  onPressed: () {
+                    Navigator.of(context).pop();
+                  }),
+            );
+          });
+    });
+  }
+
+  void _stopTimerForInactivity() {
+    _inactivityTimeout?.cancel();
+  }
+
   @override
   String get traceTitle => 'ml_kit_scan_page';
 }

packages/smooth_app/lib/pages/scan/scan_visor.dart

@@ -1,6 +1,7 @@
 import 'package:flutter/material.dart';
 import 'package:flutter_svg/flutter_svg.dart';
 import 'package:provider/provider.dart';
+import 'package:smooth_app/helpers/camera_helper.dart';
 import 'package:smooth_app/pages/scan/scan_flash_toggle.dart';
 
 /// This Widget is a [StatefulWidget], as it uses a [GlobalKey] to allow an
@@ -19,33 +20,67 @@ class ScannerVisorWidget extends StatefulWidget {
 }
 
 class ScannerVisorWidgetState extends State<ScannerVisorWidget> {
+  @override
+  void initState() {
+    super.initState();
+
+    if (mounted) {
+      CameraHelper.controller?.addListener(onCameraChanged);
+    }
+  }
+
   @override
   Widget build(BuildContext context) {
+    final bool isPaused = CameraHelper.controller?.isPaused ?? false;
+
     return Stack(
       key: Provider.of<GlobalKey<ScannerVisorWidgetState>>(context),
       children: <Widget>[
-        SizedBox.fromSize(
-          size: ScannerVisorWidget.getSize(context),
+        GestureDetector(
+          onTap: isPaused
+              ? () {
+                  CameraHelper.controller?.resumePreviewIfNecessary();
+                }
+              : null,
           child: CustomPaint(
             painter: ScanVisorPainter(),
             child: Center(
-              child: SvgPicture.asset(
-                'assets/icons/visor_icon.svg',
-                width: 35.0,
-                height: 32.0,
-              ),
+              child: isPaused
+                  ? const Icon(
+                      Icons.pause_circle_outline,
+                      color: Colors.white,
+                      size: 40.0,
+                    )
+                  : SvgPicture.asset(
+                      'assets/icons/visor_icon.svg',
+                      width: 35.0,
+                      height: 32.0,
+                    ),
             ),
           ),
         ),
         Positioned.directional(
           textDirection: Directionality.of(context),
           end: 0.0,
           bottom: 0.0,
-          child: const ScannerFlashToggleWidget(),
+          child: Offstage(
+            offstage: isPaused,
+            child: const ScannerFlashToggleWidget(),
+          ),
         )
       ],
     );
   }
+
+  void onCameraChanged() {
+    setState(() {});
+  }
+
+  @override
+  void dispose() {
+    CameraHelper.controller?.removeListener(onCameraChanged);
+    super.dispose();
+  }
 }
 
 class ScanVisorPainter extends CustomPainter {