Disable screenshots when encryption is enabled

Close #17

android/app/src/main/AndroidManifest.xml

@@ -38,6 +38,8 @@
         android:allowBackup="true"
         android:fullBackupOnly="true">
 
+        <property android:name="REQUIRE_SECURE_ENV" android:value="1" />
+
         <activity
             android:name="MainActivity"
             android:configChanges="orientation|keyboardHidden|keyboard|screenSize|smallestScreenSize|locale|layoutDirection|fontScale|screenLayout|density|uiMode"

lib/core/window_manager.dart

@@ -0,0 +1,40 @@
+// Copyright (C) 2024 Yaroslav Pronin <[email protected]>
+//
+// This file is part of Blink Comparison.
+//
+// Blink Comparison is free software: you can redistribute it and/or modify
+// it under the terms of the GNU General Public License as published by
+// the Free Software Foundation, either version 3 of the License, or
+// (at your option) any later version.
+//
+// Blink Comparison is distributed in the hope that it will be useful,
+// but WITHOUT ANY WARRANTY; without even the implied warranty of
+// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+// GNU General Public License for more details.
+//
+// You should have received a copy of the GNU General Public License
+// along with Blink Comparison.  If not, see <http://www.gnu.org/licenses/>.
+
+import 'package:flutter_windowmanager_plus/flutter_windowmanager_plus.dart';
+import 'package:injectable/injectable.dart';
+
+abstract class WindowManager {
+  /// Allow/disallow screenshots
+  Future<bool> setSecureFlag(bool enable);
+}
+
+@Singleton(as: WindowManager)
+class WindowManagerImpl implements WindowManager {
+  @override
+  Future<bool> setSecureFlag(bool enable) async {
+    if (enable) {
+      return FlutterWindowManagerPlus.addFlags(
+        FlutterWindowManagerPlus.FLAG_SECURE,
+      );
+    } else {
+      return FlutterWindowManagerPlus.clearFlags(
+        FlutterWindowManagerPlus.FLAG_SECURE,
+      );
+    }
+  }
+}

lib/main.dart

@@ -17,6 +17,7 @@
 
 import 'package:blink_comparison/core/crash_catcher/handler/notification_crash_handler.dart';
 import 'package:blink_comparison/core/settings/app_settings.dart';
+import 'package:blink_comparison/core/window_manager.dart';
 import 'package:blink_comparison/core/workmanager/thumbnails_migrator_worker.dart';
 import 'package:blink_comparison/core/workmanager/workmanager.dart';
 import 'package:blink_comparison/ui/model/app_cubit.dart';
@@ -50,7 +51,10 @@ Future<void> _main() async {
 
   runApp(
     BlocProvider(
-      create: (context) => AppCubit(getIt<AppSettings>()),
+      create: (context) => AppCubit(
+        getIt<AppSettings>(),
+        getIt<WindowManager>(),
+      ),
       child: App(
         enableDevicePreview: false,
         navigatorKey: _navigatorKey,

lib/ui/model/app_cubit.dart

@@ -18,14 +18,19 @@
 import 'dart:async';
 
 import 'package:blink_comparison/core/settings/app_settings.dart';
+import 'package:blink_comparison/core/window_manager.dart';
 import 'package:blink_comparison/ui/model/app_state.dart';
 import 'package:bloc/bloc.dart';
 
 class AppCubit extends Cubit<AppState> {
   final AppSettings _pref;
+  final WindowManager _windowManager;
   late final StreamSubscription subscription;
 
-  AppCubit(this._pref) : super(const AppState.initial());
+  AppCubit(
+    this._pref,
+    this._windowManager,
+  ) : super(const AppState.initial());
 
   Future<void> load() async {
     emit(AppState.loaded(
@@ -43,7 +48,7 @@ class AppCubit extends Cubit<AppState> {
         case AppSettingsKey.cameraFullscreenMode:
           setCameraFullscreenMode(await _pref.cameraFullscreenMode);
         case AppSettingsKey.encryptionPreference:
-          setEncryptPreference(_pref.encryptionPreferenceSync);
+          await setEncryptPreference(_pref.encryptionPreferenceSync);
       }
     });
   }
@@ -93,7 +98,7 @@ class AppCubit extends Cubit<AppState> {
     }
   }
 
-  void setEncryptPreference(EncryptionPreference? value) {
+  Future<void> setEncryptPreference(EncryptionPreference? value) async {
     if (state
         case AppState(
           :final theme?,
@@ -106,6 +111,16 @@ class AppCubit extends Cubit<AppState> {
         cameraFullscreenMode: cameraFullscreenMode,
         encrypt: value,
       ));
+      await _switchWindowSecureFlag(value);
+    }
+  }
+
+  Future<void> _switchWindowSecureFlag(EncryptionPreference? preference) async {
+    switch (preference) {
+      case null || EncryptionPreferenceNone():
+        await _windowManager.setSecureFlag(false);
+      case EncryptionPreferencePassword():
+        await _windowManager.setSecureFlag(true);
     }
   }
 }

pubspec.lock

@@ -602,6 +602,14 @@ packages:
     description: flutter
     source: sdk
     version: "0.0.0"
+  flutter_windowmanager_plus:
+    dependency: "direct main"
+    description:
+      name: flutter_windowmanager_plus
+      sha256: "4e2bf7c7f374699fd74d59785f1d74efd40052c24a5edde5a4d825cc72608d40"
+      url: "https://pub.dev"
+    source: hosted
+    version: "1.0.1"
   fluttertoast:
     dependency: "direct main"
     description:
@@ -1721,5 +1729,5 @@ packages:
     source: hosted
     version: "3.1.2"
 sdks:
-  dart: ">=3.5.0 <4.0.0"
+  dart: ">=3.5.1 <4.0.0"
   flutter: ">=3.24.0"

pubspec.yaml

@@ -91,6 +91,7 @@ dependencies:
   dynamic_color: ^1.7.0
   material_symbols_icons: ^4.2785.1
   shimmer_animation: ^2.2.1
+  flutter_windowmanager_plus: ^1.0.1
 
 dev_dependencies:
   analyzer: ^6.7.0

test/mock/mock_window_manager.dart

@@ -0,0 +1,21 @@
+// Copyright (C) 2024 Yaroslav Pronin <[email protected]>
+//
+// This file is part of Blink Comparison.
+//
+// Blink Comparison is free software: you can redistribute it and/or modify
+// it under the terms of the GNU General Public License as published by
+// the Free Software Foundation, either version 3 of the License, or
+// (at your option) any later version.
+//
+// Blink Comparison is distributed in the hope that it will be useful,
+// but WITHOUT ANY WARRANTY; without even the implied warranty of
+// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+// GNU General Public License for more details.
+//
+// You should have received a copy of the GNU General Public License
+// along with Blink Comparison.  If not, see <http://www.gnu.org/licenses/>.
+
+import 'package:blink_comparison/core/window_manager.dart';
+import 'package:mocktail/mocktail.dart';
+
+class MockWindowManager extends Mock implements WindowManager {}

test/ui/app_cubit_test.dart

@@ -19,19 +19,22 @@ import 'dart:async';
 import 'dart:ui';
 
 import 'package:blink_comparison/core/settings/app_settings.dart';
+import 'package:blink_comparison/core/window_manager.dart';
 import 'package:blink_comparison/ui/model/app_cubit.dart';
 import 'package:blink_comparison/ui/model/app_state.dart';
 import 'package:bloc_test/bloc_test.dart';
 import 'package:flutter_test/flutter_test.dart';
 import 'package:mocktail/mocktail.dart';
 
 import '../mock/mock.dart';
+import '../mock/mock_window_manager.dart';
 
 void main() {
   group('AppCubit |', () {
     late AppCubit cubit;
     late AppSettings mockPref;
     late StreamController<String> streamController;
+    late WindowManager mockWindowManager;
 
     setUpAll(() {
       streamController = StreamController.broadcast();
@@ -43,16 +46,19 @@ void main() {
 
     setUp(() async {
       mockPref = MockAppSettings();
+      mockWindowManager = MockWindowManager();
       when(() => mockPref.theme).thenAnswer(
         (_) async => const AppThemeType.system(),
       );
       when(() => mockPref.locale).thenAnswer(
         (_) async => const AppLocaleType.system(),
       );
       when(() => mockPref.cameraFullscreenMode).thenAnswer((_) async => true);
+      when(() => mockPref.encryptionPreferenceSync)
+          .thenReturn(EncryptionPreference.none());
       when(() => mockPref.changePrefStream())
           .thenAnswer((_) => streamController.stream);
-      cubit = AppCubit(mockPref);
+      cubit = AppCubit(mockPref, mockWindowManager);
       await cubit.load();
     });
 
@@ -194,5 +200,52 @@ void main() {
         ),
       ],
     );
+
+    blocTest(
+      'Change encryption preference',
+      build: () => cubit,
+      act: (AppCubit cubit) async {
+        when(() => mockWindowManager.setSecureFlag(any()))
+            .thenAnswer((_) async => true);
+        await cubit.setEncryptPreference(EncryptionPreference.password());
+        verify(() => mockWindowManager.setSecureFlag(true)).called(1);
+        await cubit.setEncryptPreference(EncryptionPreference.none());
+        verify(() => mockWindowManager.setSecureFlag(false)).called(1);
+      },
+      expect: () => [
+        const AppState.encryptPreferenceChanged(
+          theme: AppThemeType.system(),
+          locale: AppLocaleType.system(),
+          cameraFullscreenMode: true,
+          encrypt: EncryptionPreference.password(),
+        ),
+        const AppState.encryptPreferenceChanged(
+          theme: AppThemeType.system(),
+          locale: AppLocaleType.system(),
+          cameraFullscreenMode: true,
+          encrypt: EncryptionPreference.none(),
+        ),
+      ],
+    );
+
+    blocTest(
+      'Listen encryption preference change',
+      build: () => cubit,
+      act: (AppCubit cubit) {
+        when(() => mockPref.encryptionPreferenceSync)
+            .thenReturn(EncryptionPreference.none());
+        when(() => mockWindowManager.setSecureFlag(any()))
+            .thenAnswer((_) async => true);
+        streamController.add(AppSettingsKey.encryptionPreference);
+      },
+      expect: () => [
+        const AppState.encryptPreferenceChanged(
+          theme: AppThemeType.system(),
+          locale: AppLocaleType.system(),
+          cameraFullscreenMode: true,
+          encrypt: EncryptionPreference.none(),
+        ),
+      ],
+    );
   });
 }