add qr code scanning from gallery using zxing2

mobile/apps/auth/lib/l10n/arb/app_en.arb

@@ -519,5 +519,12 @@
   "algorithm": "Algorithm",
   "type": "Type",
   "period": "Period",
-  "digits": "Digits"
+  "digits": "Digits",
+  "importFromGallery": "Import from gallery",
+  "errorCouldNotReadImage": "Could not read the selected image file.",
+  "errorInvalidQRCode": "Invalid QR Code",
+  "errorInvalidQRCodeBody": "The scanned QR code is not a valid 2FA account.",
+  "errorNoQRCode": "No QR code found",
+  "errorGenericTitle": "An Error Occurred",
+  "errorGenericBody": "An unexpected error occurred while importing."
 }

mobile/apps/auth/lib/ui/home_page.dart

@@ -35,18 +35,22 @@ import 'package:ente_auth/ui/settings_page.dart';
 import 'package:ente_auth/ui/sort_option_menu.dart';
 import 'package:ente_auth/utils/dialog_util.dart';
 import 'package:ente_auth/utils/platform_util.dart';
+import 'package:ente_auth/utils/toast_util.dart';
 import 'package:ente_auth/utils/totp_util.dart';
 import 'package:ente_events/event_bus.dart';
 import 'package:ente_lock_screen/lock_screen_settings.dart';
 import 'package:ente_lock_screen/ui/app_lock.dart';
 import 'package:ente_ui/pages/base_home_page.dart';
+import 'package:file_picker/file_picker.dart';
 import 'package:flutter/foundation.dart';
 import 'package:flutter/material.dart';
 import 'package:flutter/services.dart';
 import 'package:flutter_speed_dial/flutter_speed_dial.dart';
 import 'package:flutter_staggered_grid_view/flutter_staggered_grid_view.dart';
+import 'package:image/image.dart' as img;
 import 'package:logging/logging.dart';
 import 'package:move_to_background/move_to_background.dart';
+import 'package:zxing2/qrcode.dart';
 
 class HomePage extends BaseHomePage  {
   const HomePage({super.key});
@@ -62,6 +66,7 @@ class _HomePageState extends State<HomePage> {
   );
   bool _hasLoaded = false;
   bool _isSettingsOpen = false;
+  bool _isImportingFromGallery = false;
   final Logger _logger = Logger("HomePage");
   final scaffoldKey = GlobalKey<ScaffoldState>();
 
@@ -288,6 +293,70 @@ class _HomePageState extends State<HomePage> {
     }
   }
 
+  Future<void> _importFromGallery() async {
+
+  final l10n = AppLocalizations.of(context);
+
+  if (_isImportingFromGallery) {
+    return;
+  }
+
+  setState(() {
+    _isImportingFromGallery = true;
+  });
+
+  try {
+    final FilePickerResult? result = await FilePicker.platform.pickFiles(
+      type: FileType.image,
+    );
+
+    if (result == null || result.files.single.path == null) {
+      return; 
+    }
+
+    final String imagePath = result.files.single.path!;
+    final rawImage = await File(imagePath).readAsBytes();
+    final image = img.decodeImage(rawImage);
+
+    if (image == null) {
+      await showErrorDialog(context, l10n.error, l10n.errorCouldNotReadImage);
+      return;
+    }
+
+    final source = RGBLuminanceSource(
+      image.width, image.height,
+      image.getBytes(order: img.ChannelOrder.rgba).buffer.asInt32List(),
+    );
+    final bitmap = BinaryBitmap(HybridBinarizer(source));
+    final reader = QRCodeReader();
+    final Result decodeResult = reader.decode(bitmap);
+    final String code = decodeResult.text;
+    try{
+        final newCode = Code.fromOTPAuthUrl(code);
+        await CodeStore.instance.addCode(newCode, shouldSync: false);
+    } 
+    catch (e){
+        await showErrorDialog(
+            context, l10n.errorInvalidQRCode, l10n.errorInvalidQRCodeBody,
+        );
+    }
+  }
+  on ReaderException {
+    showToast(context, l10n.errorNoQRCode);
+  }
+
+  catch (e) {
+    await showErrorDialog(
+        context, l10n.errorGenericTitle, l10n.errorGenericBody,
+    );
+  }
+  finally {
+    setState(() {
+        _isImportingFromGallery = false;
+    });
+  }
+}
+
   Future<void> _redirectToScannerPage() async {
     final Code? code = await Navigator.of(context).push(
       MaterialPageRoute(
@@ -745,6 +814,13 @@ class _HomePageState extends State<HomePage> {
           labelWidget: SpeedDialLabelWidget(context.l10n.enterDetailsManually),
           onTap: _redirectToManualEntryPage,
         ),
+        SpeedDialChild(
+          child: const Icon(Icons.image),
+          backgroundColor: Theme.of(context).colorScheme.fabBackgroundColor,
+          foregroundColor: Theme.of(context).colorScheme.fabForegroundColor,
+          labelWidget: SpeedDialLabelWidget(context.l10n.importFromGallery),
+          onTap: _importFromGallery,
+        ),
       ],
     );
   }

mobile/apps/auth/pubspec.lock

@@ -201,6 +201,14 @@ packages:
       url: "https://pub.dev"
     source: hosted
     version: "1.4.0"
+  charcode:
+    dependency: transitive
+    description:
+      name: charcode
+      sha256: fb0f1107cac15a5ea6ef0a6ef71a807b9e4267c713bb93e00e92d737cc8dbd8a
+      url: "https://pub.dev"
+    source: hosted
+    version: "1.4.0"
   checked_yaml:
     dependency: transitive
     description:
@@ -951,7 +959,7 @@ packages:
     source: hosted
     version: "0.1.0"
   image:
-    dependency: transitive
+    dependency: "direct main"
     description:
       name: image
       sha256: "4e973fcf4caae1a4be2fa0a13157aa38a8f9cb049db6529aa00b4d71abc4d928"
@@ -2021,6 +2029,14 @@ packages:
       url: "https://pub.dev"
     source: hosted
     version: "3.1.3"
+  zxing2:
+    dependency: "direct main"
+    description:
+      name: zxing2
+      sha256: "2677c49a3b9ca9457cb1d294fd4bd5041cac6aab8cdb07b216ba4e98945c684f"
+      url: "https://pub.dev"
+    source: hosted
+    version: "0.2.4"
 sdks:
   dart: ">=3.7.2 <4.0.0"
   flutter: ">=3.29.0"

mobile/apps/auth/pubspec.yaml

@@ -84,6 +84,7 @@ dependencies:
   google_nav_bar: ^5.0.5 #supported
   gradient_borders: ^1.0.0
   http: ^1.1.0
+  image: ^4.5.4
   intl: ^0.20.2
   io: ^1.0.4
   json_annotation: ^4.5.0
@@ -130,6 +131,7 @@ dependencies:
   win32: ^5.1.1
   window_manager: ^0.5.0
   xdg_directories: ^1.0.4
+  zxing2: ^0.2.4
 
 dev_dependencies:
   build_runner: ^2.1.11