chore: adopt MVVM and default `Package structure` at official

README.md

@@ -19,4 +19,6 @@ flutter run
 flutter test
 
 flutter build
+# create windows installer
+flutter pub run msix:create
 ```

docs/NFRs.md

@@ -0,0 +1,4 @@
+# Non-Functional Requirements
+
+* Package structure
+  * plz follow official [Package structure](https://docs.flutter.dev/app-architecture/case-study#package-structure) with a slight modification, put each `<FEATURE NAME>/`s in `features/` sub-directory under `ui/`.

lib/app.dart

@@ -1,6 +1,6 @@
 import 'package:flutter/material.dart';
 import 'package:flutter_riverpod/flutter_riverpod.dart';
-import 'package:pdf_signature/features/pdf/viewer.dart';
+import 'package:pdf_signature/ui/features/pdf/widgets/pdf_screen.dart';
 
 class MyApp extends StatelessWidget {
   const MyApp({super.key});

lib/data/model/model.dart

@@ -0,0 +1,91 @@
+import 'dart:typed_data';
+import 'package:flutter/widgets.dart';
+
+class PdfState {
+  final bool loaded;
+  final int pageCount;
+  final int currentPage;
+  final bool markedForSigning;
+  final String? pickedPdfPath;
+  final Uint8List? pickedPdfBytes;
+  final int? signedPage;
+  const PdfState({
+    required this.loaded,
+    required this.pageCount,
+    required this.currentPage,
+    required this.markedForSigning,
+    this.pickedPdfPath,
+    this.pickedPdfBytes,
+    this.signedPage,
+  });
+  factory PdfState.initial() => const PdfState(
+    loaded: false,
+    pageCount: 0,
+    currentPage: 1,
+    markedForSigning: false,
+    pickedPdfBytes: null,
+    signedPage: null,
+  );
+  PdfState copyWith({
+    bool? loaded,
+    int? pageCount,
+    int? currentPage,
+    bool? markedForSigning,
+    String? pickedPdfPath,
+    Uint8List? pickedPdfBytes,
+    int? signedPage,
+  }) => PdfState(
+    loaded: loaded ?? this.loaded,
+    pageCount: pageCount ?? this.pageCount,
+    currentPage: currentPage ?? this.currentPage,
+    markedForSigning: markedForSigning ?? this.markedForSigning,
+    pickedPdfPath: pickedPdfPath ?? this.pickedPdfPath,
+    pickedPdfBytes: pickedPdfBytes ?? this.pickedPdfBytes,
+    signedPage: signedPage ?? this.signedPage,
+  );
+}
+
+class SignatureState {
+  final Rect? rect;
+  final bool aspectLocked;
+  final bool bgRemoval;
+  final double contrast;
+  final double brightness;
+  final List<List<Offset>> strokes;
+  final Uint8List? imageBytes;
+  const SignatureState({
+    required this.rect,
+    required this.aspectLocked,
+    required this.bgRemoval,
+    required this.contrast,
+    required this.brightness,
+    required this.strokes,
+    this.imageBytes,
+  });
+  factory SignatureState.initial() => const SignatureState(
+    rect: null,
+    aspectLocked: false,
+    bgRemoval: false,
+    contrast: 1.0,
+    brightness: 0.0,
+    strokes: [],
+    imageBytes: null,
+  );
+  SignatureState copyWith({
+    Rect? rect,
+    bool? aspectLocked,
+    bool? bgRemoval,
+    double? contrast,
+    double? brightness,
+    List<List<Offset>>? strokes,
+    Uint8List? imageBytes,
+  }) => SignatureState(
+    rect: rect ?? this.rect,
+    aspectLocked: aspectLocked ?? this.aspectLocked,
+    bgRemoval: bgRemoval ?? this.bgRemoval,
+    contrast: contrast ?? this.contrast,
+    brightness: brightness ?? this.brightness,
+    strokes: strokes ?? this.strokes,
+    imageBytes: imageBytes ?? this.imageBytes,
+  );
+}

lib/data/services/providers.dart

@@ -0,0 +1,45 @@
+import 'package:flutter_riverpod/flutter_riverpod.dart';
+import 'package:path_provider/path_provider.dart' as pp;
+import 'package:file_selector/file_selector.dart' as fs;
+import 'package:pdf_signature/data/services/export_service.dart';
+
+// Feature-scoped DI and configuration providers
+
+// Toggle mock viewer (used by tests to show a gray placeholder instead of real PDF pages)
+final useMockViewerProvider = Provider<bool>((_) => false);
+
+// Export service injection for testability
+final exportServiceProvider = Provider<ExportService>((_) => ExportService());
+
+// Export DPI setting (points per inch mapping), default 144 DPI
+final exportDpiProvider = StateProvider<double>((_) => 144.0);
+
+// Controls whether signature overlay is visible (used to hide on non-stamped pages during export)
+final signatureVisibilityProvider = StateProvider<bool>((_) => true);
+
+// Save path picker (injected for tests)
+final savePathPickerProvider = Provider<Future<String?> Function()>((ref) {
+  return () async {
+    String? initialDir;
+    try {
+      final d = await pp.getDownloadsDirectory();
+      initialDir = d?.path;
+    } catch (_) {}
+    if (initialDir == null) {
+      try {
+        final d = await pp.getApplicationDocumentsDirectory();
+        initialDir = d.path;
+      } catch (_) {}
+    }
+    final location = await fs.getSaveLocation(
+      suggestedName: 'signed.pdf',
+      acceptedTypeGroups: [
+        const fs.XTypeGroup(label: 'PDF', extensions: ['pdf']),
+      ],
+      initialDirectory: initialDir,
+    );
+    if (location == null) return null;
+    final path = location.path;
+    return path.toLowerCase().endsWith('.pdf') ? path : '$path.pdf';
+  };
+});

lib/ui/features/pdf/view_model/view_model.dart

@@ -1,52 +1,14 @@
-part of 'viewer.dart';
+import 'dart:math' as math;
+import 'dart:typed_data';
+import 'package:flutter/material.dart';
+import 'package:flutter_riverpod/flutter_riverpod.dart';
 
-class PdfState {
-  final bool loaded;
-  final int pageCount;
-  final int currentPage;
-  final bool markedForSigning;
-  final String? pickedPdfPath;
-  final Uint8List? pickedPdfBytes;
-  final int? signedPage;
-  const PdfState({
-    required this.loaded,
-    required this.pageCount,
-    required this.currentPage,
-    required this.markedForSigning,
-    this.pickedPdfPath,
-    this.pickedPdfBytes,
-    this.signedPage,
-  });
-  factory PdfState.initial() => const PdfState(
-    loaded: false,
-    pageCount: 0,
-    currentPage: 1,
-    markedForSigning: false,
-    pickedPdfBytes: null,
-    signedPage: null,
-  );
-  PdfState copyWith({
-    bool? loaded,
-    int? pageCount,
-    int? currentPage,
-    bool? markedForSigning,
-    String? pickedPdfPath,
-    Uint8List? pickedPdfBytes,
-    int? signedPage,
-  }) => PdfState(
-    loaded: loaded ?? this.loaded,
-    pageCount: pageCount ?? this.pageCount,
-    currentPage: currentPage ?? this.currentPage,
-    markedForSigning: markedForSigning ?? this.markedForSigning,
-    pickedPdfPath: pickedPdfPath ?? this.pickedPdfPath,
-    pickedPdfBytes: pickedPdfBytes ?? this.pickedPdfBytes,
-    signedPage: signedPage ?? this.signedPage,
-  );
-}
+import '../../../../data/model/model.dart';
 
 class PdfController extends StateNotifier<PdfState> {
   PdfController() : super(PdfState.initial());
   static const int samplePageCount = 5;
+
   void openSample() {
     state = state.copyWith(
       loaded: true,
@@ -102,51 +64,6 @@ final pdfProvider = StateNotifierProvider<PdfController, PdfState>(
   (ref) => PdfController(),
 );
 
-class SignatureState {
-  final Rect? rect;
-  final bool aspectLocked;
-  final bool bgRemoval;
-  final double contrast;
-  final double brightness;
-  final List<List<Offset>> strokes;
-  final Uint8List? imageBytes;
-  const SignatureState({
-    required this.rect,
-    required this.aspectLocked,
-    required this.bgRemoval,
-    required this.contrast,
-    required this.brightness,
-    required this.strokes,
-    this.imageBytes,
-  });
-  factory SignatureState.initial() => const SignatureState(
-    rect: null,
-    aspectLocked: false,
-    bgRemoval: false,
-    contrast: 1.0,
-    brightness: 0.0,
-    strokes: [],
-    imageBytes: null,
-  );
-  SignatureState copyWith({
-    Rect? rect,
-    bool? aspectLocked,
-    bool? bgRemoval,
-    double? contrast,
-    double? brightness,
-    List<List<Offset>>? strokes,
-    Uint8List? imageBytes,
-  }) => SignatureState(
-    rect: rect ?? this.rect,
-    aspectLocked: aspectLocked ?? this.aspectLocked,
-    bgRemoval: bgRemoval ?? this.bgRemoval,
-    contrast: contrast ?? this.contrast,
-    brightness: brightness ?? this.brightness,
-    strokes: strokes ?? this.strokes,
-    imageBytes: imageBytes ?? this.imageBytes,
-  );
-}
-
 class SignatureController extends StateNotifier<SignatureState> {
   SignatureController() : super(SignatureState.initial());
   static const Size pageSize = Size(400, 560);

lib/ui/features/pdf/widgets/draw_canvas.dart

@@ -1,4 +1,7 @@
-part of 'viewer.dart';
+import 'dart:math' as math;
+import 'dart:typed_data';
+import 'package:flutter/material.dart';
+import 'package:hand_signature/signature.dart' as hand;
 
 class DrawCanvas extends StatefulWidget {
   const DrawCanvas({
@@ -52,11 +55,8 @@ class _DrawCanvasState extends State<DrawCanvas> {
                       height: 512,
                     );
                     final bytes = data?.buffer.asUint8List();
-                    // print("onPressed, Exported signature bytes: ${bytes?.length}");
-                    // Notify tests if provided
                     widget.debugBytesSink?.value = bytes;
                     if (widget.onConfirm != null) {
-                      // print("onConfirm callback called");
                       widget.onConfirm!(bytes);
                     } else {
                       if (context.mounted) {

lib/ui/features/pdf/widgets/pdf_screen.dart

@@ -1,51 +1,16 @@
 import 'dart:math' as math;
+import 'dart:typed_data';
 import 'package:file_selector/file_selector.dart' as fs;
-import 'package:flutter/material.dart';
 import 'package:flutter/foundation.dart' show kIsWeb;
+import 'package:flutter/material.dart';
 import 'package:flutter_riverpod/flutter_riverpod.dart';
 import 'package:pdfrx/pdfrx.dart';
-import 'package:path_provider/path_provider.dart' as pp;
-import 'dart:typed_data';
-import '../share/export_service.dart';
-import 'package:hand_signature/signature.dart' as hand;
 import 'package:printing/printing.dart' as printing;
 
-part 'viewer_state.dart';
-part 'viewer_widgets.dart';
-
-final useMockViewerProvider = Provider<bool>((_) => false);
-// Export service injection for testability
-final exportServiceProvider = Provider<ExportService>((_) => ExportService());
-// Export DPI setting (points per inch mapping), default 144 DPI
-final exportDpiProvider = StateProvider<double>((_) => 144.0);
-// Controls whether signature overlay is visible (used to hide on non-stamped pages during export)
-final signatureVisibilityProvider = StateProvider<bool>((_) => true);
-// Save path picker (injected for tests)
-final savePathPickerProvider = Provider<Future<String?> Function()>((ref) {
-  return () async {
-    String? initialDir;
-    try {
-      final d = await pp.getDownloadsDirectory();
-      initialDir = d?.path;
-    } catch (_) {}
-    if (initialDir == null) {
-      try {
-        final d = await pp.getApplicationDocumentsDirectory();
-        initialDir = d.path;
-      } catch (_) {}
-    }
-    final location = await fs.getSaveLocation(
-      suggestedName: 'signed.pdf',
-      acceptedTypeGroups: [
-        const fs.XTypeGroup(label: 'PDF', extensions: ['pdf']),
-      ],
-      initialDirectory: initialDir,
-    );
-    if (location == null) return null;
-    final path = location.path;
-    return path.toLowerCase().endsWith('.pdf') ? path : '$path.pdf';
-  };
-});
+import '../../../../data/model/model.dart';
+import '../../../../data/services/providers.dart';
+import '../view_model/view_model.dart';
+import 'draw_canvas.dart';
 
 class PdfSignatureHomePage extends ConsumerStatefulWidget {
   const PdfSignatureHomePage({super.key});
@@ -102,8 +67,6 @@ class _PdfSignatureHomePageState extends ConsumerState<PdfSignatureHomePage> {
     sig.setImageBytes(bytes);
   }
 
-  // removed invalid loader; not part of normal app
-
   void _onDragSignature(Offset delta) {
     ref.read(signatureProvider.notifier).drag(delta);
   }
@@ -239,8 +202,6 @@ class _PdfSignatureHomePageState extends ConsumerState<PdfSignatureHomePage> {
     }
   }
 
-  // Removed manual full-path dialog; using file_selector.getSaveLocation via provider
-
   String _ensurePdfExtension(String name) {
     if (!name.toLowerCase().endsWith('.pdf')) return '$name.pdf';
     return name;

pubspec.yaml

@@ -39,12 +39,13 @@ dependencies:
   flutter_dotenv: ^6.0.0
   file_selector: ^1.0.3
   path_provider: ^2.1.5
-  pdfrx: ^1.3.5
+  pdfrx: ^2.1.9
   pdf: ^3.10.8
   hand_signature: ^3.1.0+2
   image: ^4.2.0
   printing: ^5.14.2
   result_dart: ^2.1.1
+  go_router: ^16.2.0
 
 dev_dependencies:
   flutter_test:
@@ -57,7 +58,9 @@ dev_dependencies:
   # activated in the `analysis_options.yaml` file located at the root of your
   # package. See that file for information about deactivating specific lint
   # rules and activating additional ones.
-  flutter_lints: ^5.0.0
+  flutter_lints: ^6.0.0
+  msix: ^3.16.12
+  json_serializable: ^6.11.0
 
 # For information on the generic Dart part of this file, see the
 # following page: https://dart.dev/tools/pub/pubspec

test/export_signature_test.dart

@@ -7,7 +7,7 @@ import 'package:image/image.dart' as img;
 import 'package:pdf/pdf.dart' as pdf;
 import 'package:pdf/widgets.dart' as pw;
 
-import 'package:pdf_signature/features/share/export_service.dart';
+import 'package:pdf_signature/data/services/export_service.dart';
 
 void main() {
   test(

test/features/step/_helpers.dart

@@ -2,7 +2,7 @@ import 'dart:typed_data';
 import 'dart:ui' show Rect, Size;
 import 'dart:io';
 import 'package:flutter_riverpod/flutter_riverpod.dart';
-import 'package:pdf_signature/features/pdf/viewer.dart';
+import 'package:pdf_signature/ui/features/pdf/view_model/view_model.dart';
 import '_world.dart';
 
 // A lightweight fake exporter to avoid platform rasterization in tests.

test/features/step/a_default_signature_rect_is_placed.dart

@@ -1,5 +1,5 @@
 import 'package:flutter_test/flutter_test.dart';
-import 'package:pdf_signature/features/pdf/viewer.dart';
+import 'package:pdf_signature/ui/features/pdf/view_model/view_model.dart';
 import '_world.dart';
 
 /// Usage: a default signature rect is placed

test/features/step/a_drawn_signature_exists_in_the_canvas.dart

@@ -1,6 +1,6 @@
 import 'package:flutter_test/flutter_test.dart';
 import 'package:flutter_riverpod/flutter_riverpod.dart';
-import 'package:pdf_signature/features/pdf/viewer.dart';
+import 'package:pdf_signature/ui/features/pdf/view_model/view_model.dart';
 import '_world.dart';
 
 /// Usage: a drawn signature exists in the canvas

test/features/step/a_multipage_pdf_is_open.dart

@@ -1,6 +1,6 @@
 import 'package:flutter_test/flutter_test.dart';
 import 'package:flutter_riverpod/flutter_riverpod.dart';
-import 'package:pdf_signature/features/pdf/viewer.dart';
+import 'package:pdf_signature/ui/features/pdf/view_model/view_model.dart';
 import '_world.dart';
 
 /// Usage: a multi-page PDF is open

test/features/step/a_pdf_document_is_available.dart

@@ -1,6 +1,6 @@
 import 'package:flutter_test/flutter_test.dart';
 import 'package:flutter_riverpod/flutter_riverpod.dart';
-import 'package:pdf_signature/features/pdf/viewer.dart';
+import 'package:pdf_signature/ui/features/pdf/view_model/view_model.dart';
 import '_world.dart';
 
 /// Usage: a PDF document is available

test/features/step/a_pdf_is_open_and_contains_at_least_one_placed_signature.dart

@@ -1,7 +1,7 @@
 import 'dart:typed_data';
 import 'package:flutter_test/flutter_test.dart';
 import 'package:flutter_riverpod/flutter_riverpod.dart';
-import 'package:pdf_signature/features/pdf/viewer.dart';
+import 'package:pdf_signature/ui/features/pdf/view_model/view_model.dart';
 import '_world.dart';
 
 /// Usage: a PDF is open and contains at least one placed signature

test/features/step/a_pdf_is_open_with_no_signatures_placed.dart

@@ -1,6 +1,6 @@
 import 'package:flutter_test/flutter_test.dart';
 import 'package:flutter_riverpod/flutter_riverpod.dart';
-import 'package:pdf_signature/features/pdf/viewer.dart';
+import 'package:pdf_signature/ui/features/pdf/view_model/view_model.dart';
 import '_world.dart';
 
 /// Usage: a PDF is open with no signatures placed

test/features/step/a_pdf_is_open_with_path_and_pagecount.dart

@@ -1,5 +1,5 @@
 import 'package:flutter_test/flutter_test.dart';
-import 'package:pdf_signature/features/pdf/viewer.dart';
+import 'package:pdf_signature/ui/features/pdf/view_model/view_model.dart';
 import '_world.dart';
 
 /// Usage: a pdf is open with path {'test.pdf'} and pageCount {5}

test/features/step/a_pdf_page_is_selected_for_signing.dart

@@ -1,6 +1,6 @@
 import 'package:flutter_test/flutter_test.dart';
 import 'package:flutter_riverpod/flutter_riverpod.dart';
-import 'package:pdf_signature/features/pdf/viewer.dart';
+import 'package:pdf_signature/ui/features/pdf/view_model/view_model.dart';
 import '_world.dart';
 
 /// Usage: a PDF page is selected for signing

test/features/step/a_signature_image_is_created.dart

@@ -1,6 +1,6 @@
 import 'package:flutter_test/flutter_test.dart';
 import 'package:flutter_riverpod/flutter_riverpod.dart';
-import 'package:pdf_signature/features/pdf/viewer.dart';
+import 'package:pdf_signature/ui/features/pdf/view_model/view_model.dart';
 import '_world.dart';
 
 /// Usage: a signature image is created

test/features/step/a_signature_image_is_placed_on_the_page.dart

@@ -1,7 +1,7 @@
 import 'dart:typed_data';
 import 'package:flutter_test/flutter_test.dart';
 import 'package:flutter_riverpod/flutter_riverpod.dart';
-import 'package:pdf_signature/features/pdf/viewer.dart';
+import 'package:pdf_signature/ui/features/pdf/view_model/view_model.dart';
 import '_world.dart';
 
 /// Usage: a signature image is placed on the page

test/features/step/a_signature_image_is_selected.dart

@@ -1,7 +1,7 @@
 import 'dart:typed_data';
 import 'package:flutter_test/flutter_test.dart';
 import 'package:flutter_riverpod/flutter_riverpod.dart';
-import 'package:pdf_signature/features/pdf/viewer.dart';
+import 'package:pdf_signature/ui/features/pdf/view_model/view_model.dart';
 import '_world.dart';
 
 /// Usage: a signature image is selected

test/features/step/a_signature_is_placed_with_a_position_and_size_relative_to_the_page.dart

@@ -2,7 +2,7 @@ import 'dart:typed_data';
 import 'dart:ui';
 import 'package:flutter_test/flutter_test.dart';
 import 'package:flutter_riverpod/flutter_riverpod.dart';
-import 'package:pdf_signature/features/pdf/viewer.dart';
+import 'package:pdf_signature/ui/features/pdf/view_model/view_model.dart';
 import '_world.dart';
 
 /// Usage: a signature is placed with a position and size relative to the page

test/features/step/an_empty_signature_canvas.dart

@@ -1,6 +1,6 @@
 import 'package:flutter_test/flutter_test.dart';
 import 'package:flutter_riverpod/flutter_riverpod.dart';
-import 'package:pdf_signature/features/pdf/viewer.dart';
+import 'package:pdf_signature/ui/features/pdf/view_model/view_model.dart';
 import '_world.dart';
 
 /// Usage: an empty signature canvas

test/features/step/aspect_lock_is.dart

@@ -1,5 +1,5 @@
 import 'package:flutter_test/flutter_test.dart';
-import 'package:pdf_signature/features/pdf/viewer.dart';
+import 'package:pdf_signature/ui/features/pdf/view_model/view_model.dart';
 import '_world.dart';
 
 /// Usage: aspect lock is {true}

test/features/step/i_drag_signature_by.dart

@@ -1,6 +1,6 @@
 import 'package:flutter/material.dart';
 import 'package:flutter_test/flutter_test.dart';
-import 'package:pdf_signature/features/pdf/viewer.dart';
+import 'package:pdf_signature/ui/features/pdf/view_model/view_model.dart';
 import '_world.dart';
 
 /// Usage: I drag signature by {Offset(10000, -10000)}

test/features/step/i_jumpto.dart

@@ -1,5 +1,5 @@
 import 'package:flutter_test/flutter_test.dart';
-import 'package:pdf_signature/features/pdf/viewer.dart';
+import 'package:pdf_signature/ui/features/pdf/view_model/view_model.dart';
 import '_world.dart';
 
 /// Usage: I jumpTo {10}

test/features/step/i_openpicked_with_path_and_pagecount.dart

@@ -1,5 +1,5 @@
 import 'package:flutter_test/flutter_test.dart';
-import 'package:pdf_signature/features/pdf/viewer.dart';
+import 'package:pdf_signature/ui/features/pdf/view_model/view_model.dart';
 import '_world.dart';
 
 /// Usage: I openPicked with path {'test.pdf'} and pageCount {7}

test/features/step/i_place_default_signature_rect.dart

@@ -1,5 +1,5 @@
 import 'package:flutter_test/flutter_test.dart';
-import 'package:pdf_signature/features/pdf/viewer.dart';
+import 'package:pdf_signature/ui/features/pdf/view_model/view_model.dart';
 import '_world.dart';
 
 /// Usage: I place default signature rect

test/features/step/i_resize_signature_by.dart

@@ -1,6 +1,6 @@
 import 'package:flutter/material.dart';
 import 'package:flutter_test/flutter_test.dart';
-import 'package:pdf_signature/features/pdf/viewer.dart';
+import 'package:pdf_signature/ui/features/pdf/view_model/view_model.dart';
 import '_world.dart';
 
 /// Usage: I resize signature by {Offset(1000, 1000)}

test/features/step/i_set_page_count.dart

@@ -1,5 +1,5 @@
 import 'package:flutter_test/flutter_test.dart';
-import 'package:pdf_signature/features/pdf/viewer.dart';
+import 'package:pdf_signature/ui/features/pdf/view_model/view_model.dart';
 import '_world.dart';
 
 /// Usage: I set page count {9}

test/features/step/i_set_signature_image_bytes.dart

@@ -1,6 +1,6 @@
 import 'dart:typed_data';
 import 'package:flutter_test/flutter_test.dart';
-import 'package:pdf_signature/features/pdf/viewer.dart';
+import 'package:pdf_signature/ui/features/pdf/view_model/view_model.dart';
 import '_world.dart';
 
 /// Usage: I set signature image bytes {Uint8List.fromList([0, 1, 2])}

test/features/step/i_set_tiny_signature_image_bytes.dart

@@ -1,6 +1,6 @@
 import 'dart:typed_data';
 import 'package:flutter_test/flutter_test.dart';
-import 'package:pdf_signature/features/pdf/viewer.dart';
+import 'package:pdf_signature/ui/features/pdf/view_model/view_model.dart';
 import '_world.dart';
 
 /// Usage: I set tiny signature image bytes

test/features/step/i_toggle_mark.dart

@@ -1,5 +1,5 @@
 import 'package:flutter_test/flutter_test.dart';
-import 'package:pdf_signature/features/pdf/viewer.dart';
+import 'package:pdf_signature/ui/features/pdf/view_model/view_model.dart';
 import '_world.dart';
 
 /// Usage: I toggle mark

test/features/step/it_is_placed_on_the_selected_page.dart

@@ -1,6 +1,6 @@
 import 'package:flutter_test/flutter_test.dart';
 import 'package:flutter_riverpod/flutter_riverpod.dart';
-import 'package:pdf_signature/features/pdf/viewer.dart';
+import 'package:pdf_signature/ui/features/pdf/view_model/view_model.dart';
 import '_world.dart';
 
 /// Usage: it is placed on the selected page

test/features/step/multiple_strokes_were_drawn.dart

@@ -1,6 +1,6 @@
 import 'package:flutter_test/flutter_test.dart';
 import 'package:flutter_riverpod/flutter_riverpod.dart';
-import 'package:pdf_signature/features/pdf/viewer.dart';
+import 'package:pdf_signature/ui/features/pdf/view_model/view_model.dart';
 import '_world.dart';
 
 /// Usage: multiple strokes were drawn

test/features/step/nearwhite_background_becomes_transparent_in_the_preview.dart

@@ -1,6 +1,6 @@
 import 'package:flutter_test/flutter_test.dart';
 import 'package:flutter_riverpod/flutter_riverpod.dart';
-import 'package:pdf_signature/features/pdf/viewer.dart';
+import 'package:pdf_signature/ui/features/pdf/view_model/view_model.dart';
 import '_world.dart';
 
 /// Usage: near-white background becomes transparent in the preview

test/features/step/pdf_current_page_is.dart

@@ -1,5 +1,5 @@
 import 'package:flutter_test/flutter_test.dart';
-import 'package:pdf_signature/features/pdf/viewer.dart';
+import 'package:pdf_signature/ui/features/pdf/view_model/view_model.dart';
 import '_world.dart';
 
 /// Usage: pdf current page is {1}

test/features/step/pdf_marked_for_signing_is.dart

@@ -1,5 +1,5 @@
 import 'package:flutter_test/flutter_test.dart';
-import 'package:pdf_signature/features/pdf/viewer.dart';
+import 'package:pdf_signature/ui/features/pdf/view_model/view_model.dart';
 import '_world.dart';
 
 /// Usage: pdf marked for signing is {false}

test/features/step/pdf_page_count_is.dart

@@ -1,5 +1,5 @@
 import 'package:flutter_test/flutter_test.dart';
-import 'package:pdf_signature/features/pdf/viewer.dart';
+import 'package:pdf_signature/ui/features/pdf/view_model/view_model.dart';
 import '_world.dart';
 
 /// Usage: pdf page count is {7}

test/features/step/pdf_picked_path_is.dart

@@ -1,5 +1,5 @@
 import 'package:flutter_test/flutter_test.dart';
-import 'package:pdf_signature/features/pdf/viewer.dart';
+import 'package:pdf_signature/ui/features/pdf/view_model/view_model.dart';
 import '_world.dart';
 
 /// Usage: pdf picked path is {'test.pdf'}

test/features/step/pdf_state_is_loaded.dart

@@ -1,5 +1,5 @@
 import 'package:flutter_test/flutter_test.dart';
-import 'package:pdf_signature/features/pdf/viewer.dart';
+import 'package:pdf_signature/ui/features/pdf/view_model/view_model.dart';
 import '_world.dart';
 
 /// Usage: pdf state is loaded {true}

test/features/step/signature_aspect_ratio_is_preserved_within.dart

@@ -1,5 +1,5 @@
 import 'package:flutter_test/flutter_test.dart';
-import 'package:pdf_signature/features/pdf/viewer.dart';
+import 'package:pdf_signature/ui/features/pdf/view_model/view_model.dart';
 import '_world.dart';
 
 /// Usage: signature aspect ratio is preserved within {0.05}

test/features/step/signature_image_bytes_is_not_null.dart

@@ -1,5 +1,5 @@
 import 'package:flutter_test/flutter_test.dart';
-import 'package:pdf_signature/features/pdf/viewer.dart';
+import 'package:pdf_signature/ui/features/pdf/view_model/view_model.dart';
 import '_world.dart';
 
 /// Usage: signature image bytes is not null

test/features/step/signature_rect_bottom.dart

@@ -1,5 +1,5 @@
 import 'package:flutter_test/flutter_test.dart';
-import 'package:pdf_signature/features/pdf/viewer.dart';
+import 'package:pdf_signature/ui/features/pdf/view_model/view_model.dart';
 import '_world.dart';
 
 /// Usage: signature rect bottom <= {560}

test/features/step/signature_rect_height.dart

@@ -1,5 +1,5 @@
 import 'package:flutter_test/flutter_test.dart';
-import 'package:pdf_signature/features/pdf/viewer.dart';
+import 'package:pdf_signature/ui/features/pdf/view_model/view_model.dart';
 import '_world.dart';
 
 /// Usage: signature rect height > {20}

test/features/step/signature_rect_is_not_null.dart

@@ -1,5 +1,5 @@
 import 'package:flutter_test/flutter_test.dart';
-import 'package:pdf_signature/features/pdf/viewer.dart';
+import 'package:pdf_signature/ui/features/pdf/view_model/view_model.dart';
 import '_world.dart';
 
 /// Usage: signature rect is not null

test/features/step/signature_rect_is_null.dart

@@ -1,5 +1,5 @@
 import 'package:flutter_test/flutter_test.dart';
-import 'package:pdf_signature/features/pdf/viewer.dart';
+import 'package:pdf_signature/ui/features/pdf/view_model/view_model.dart';
 import '_world.dart';
 
 /// Usage: signature rect is null

test/features/step/signature_rect_left.dart

@@ -1,5 +1,5 @@
 import 'package:flutter_test/flutter_test.dart';
-import 'package:pdf_signature/features/pdf/viewer.dart';
+import 'package:pdf_signature/ui/features/pdf/view_model/view_model.dart';
 import '_world.dart';
 
 /// Usage: signature rect left >= {0}

test/features/step/signature_rect_moved_from_center.dart

@@ -1,5 +1,5 @@
 import 'package:flutter_test/flutter_test.dart';
-import 'package:pdf_signature/features/pdf/viewer.dart';
+import 'package:pdf_signature/ui/features/pdf/view_model/view_model.dart';
 import '_world.dart';
 
 /// Usage: signature rect moved from center

test/features/step/signature_rect_right.dart

@@ -1,5 +1,5 @@
 import 'package:flutter_test/flutter_test.dart';
-import 'package:pdf_signature/features/pdf/viewer.dart';
+import 'package:pdf_signature/ui/features/pdf/view_model/view_model.dart';
 import '_world.dart';
 
 /// Usage: signature rect right <= {400}

test/features/step/signature_rect_top.dart

@@ -1,5 +1,5 @@
 import 'package:flutter_test/flutter_test.dart';
-import 'package:pdf_signature/features/pdf/viewer.dart';
+import 'package:pdf_signature/ui/features/pdf/view_model/view_model.dart';
 import '_world.dart';
 
 /// Usage: signature rect top >= {0}

test/features/step/signature_rect_width.dart

@@ -1,5 +1,5 @@
 import 'package:flutter_test/flutter_test.dart';
-import 'package:pdf_signature/features/pdf/viewer.dart';
+import 'package:pdf_signature/ui/features/pdf/view_model/view_model.dart';
 import '_world.dart';
 
 /// Usage: signature rect width > {50}

test/features/step/that_page_is_displayed.dart

@@ -1,6 +1,6 @@
 import 'package:flutter_test/flutter_test.dart';
 import 'package:flutter_riverpod/flutter_riverpod.dart';
-import 'package:pdf_signature/features/pdf/viewer.dart';
+import 'package:pdf_signature/ui/features/pdf/view_model/view_model.dart';
 import '_world.dart';
 
 /// Usage: that page is displayed

test/features/step/the_canvas_becomes_blank.dart

@@ -1,6 +1,6 @@
 import 'package:flutter_test/flutter_test.dart';
 import 'package:flutter_riverpod/flutter_riverpod.dart';
-import 'package:pdf_signature/features/pdf/viewer.dart';
+import 'package:pdf_signature/ui/features/pdf/view_model/view_model.dart';
 import '_world.dart';
 
 /// Usage: the canvas becomes blank

test/features/step/the_first_page_is_displayed.dart

@@ -1,6 +1,6 @@
 import 'package:flutter_test/flutter_test.dart';
 import 'package:flutter_riverpod/flutter_riverpod.dart';
-import 'package:pdf_signature/features/pdf/viewer.dart';
+import 'package:pdf_signature/ui/features/pdf/view_model/view_model.dart';
 import '_world.dart';
 
 /// Usage: the first page is displayed

test/features/step/the_image_is_loaded_and_shown_as_a_signature_asset.dart

@@ -1,6 +1,6 @@
 import 'package:flutter_test/flutter_test.dart';
 import 'package:flutter_riverpod/flutter_riverpod.dart';
-import 'package:pdf_signature/features/pdf/viewer.dart';
+import 'package:pdf_signature/ui/features/pdf/view_model/view_model.dart';
 import '_world.dart';
 
 /// Usage: the image is loaded and shown as a signature asset

test/features/step/the_image_is_not_added_to_the_document.dart

@@ -1,6 +1,6 @@
 import 'package:flutter_test/flutter_test.dart';
 import 'package:flutter_riverpod/flutter_riverpod.dart';
-import 'package:pdf_signature/features/pdf/viewer.dart';
+import 'package:pdf_signature/ui/features/pdf/view_model/view_model.dart';
 import '_world.dart';
 
 /// Usage: the image is not added to the document

test/features/step/the_image_scales_proportionally.dart

@@ -1,6 +1,6 @@
 import 'package:flutter_test/flutter_test.dart';
 import 'package:flutter_riverpod/flutter_riverpod.dart';
-import 'package:pdf_signature/features/pdf/viewer.dart';
+import 'package:pdf_signature/ui/features/pdf/view_model/view_model.dart';
 import '_world.dart';
 
 /// Usage: the image scales proportionally

test/features/step/the_last_stroke_is_removed.dart

@@ -1,6 +1,6 @@
 import 'package:flutter_test/flutter_test.dart';
 import 'package:flutter_riverpod/flutter_riverpod.dart';
-import 'package:pdf_signature/features/pdf/viewer.dart';
+import 'package:pdf_signature/ui/features/pdf/view_model/view_model.dart';
 import '_world.dart';
 
 /// Usage: the last stroke is removed

test/features/step/the_preview_updates_immediately.dart

@@ -1,6 +1,6 @@
 import 'package:flutter_test/flutter_test.dart';
 import 'package:flutter_riverpod/flutter_riverpod.dart';
-import 'package:pdf_signature/features/pdf/viewer.dart';
+import 'package:pdf_signature/ui/features/pdf/view_model/view_model.dart';
 import '_world.dart';
 
 /// Usage: the preview updates immediately

test/features/step/the_signature_is_stamped_at_the_exact_pdf_page_coordinates_and_size.dart

@@ -1,6 +1,6 @@
 import 'package:flutter_test/flutter_test.dart';
 import 'package:flutter_riverpod/flutter_riverpod.dart';
-import 'package:pdf_signature/features/pdf/viewer.dart';
+import 'package:pdf_signature/ui/features/pdf/view_model/view_model.dart';
 import '_world.dart';
 
 /// Usage: the signature is stamped at the exact PDF page coordinates and size

test/features/step/the_signature_remains_within_the_page_area.dart

@@ -1,6 +1,6 @@
 import 'package:flutter_test/flutter_test.dart';
 import 'package:flutter_riverpod/flutter_riverpod.dart';
-import 'package:pdf_signature/features/pdf/viewer.dart';
+import 'package:pdf_signature/ui/features/pdf/view_model/view_model.dart';
 import '_world.dart';
 
 /// Usage: the signature remains within the page area

test/features/step/the_signatures_appear_on_the_corresponding_page_in_the_output.dart

@@ -1,6 +1,6 @@
 import 'package:flutter_test/flutter_test.dart';
 import 'package:flutter_riverpod/flutter_riverpod.dart';
-import 'package:pdf_signature/features/pdf/viewer.dart';
+import 'package:pdf_signature/ui/features/pdf/view_model/view_model.dart';
 import '_world.dart';
 
 /// Usage: the signatures appear on the corresponding page in the output

test/features/step/the_size_and_position_update_in_real_time.dart

@@ -1,6 +1,6 @@
 import 'package:flutter_test/flutter_test.dart';
 import 'package:flutter_riverpod/flutter_riverpod.dart';
-import 'package:pdf_signature/features/pdf/viewer.dart';
+import 'package:pdf_signature/ui/features/pdf/view_model/view_model.dart';
 import '_world.dart';
 
 /// Usage: the size and position update in real time

test/features/step/the_user_attempts_to_save.dart

@@ -1,6 +1,6 @@
 import 'package:flutter_test/flutter_test.dart';
 import 'package:flutter_riverpod/flutter_riverpod.dart';
-import 'package:pdf_signature/features/pdf/viewer.dart';
+import 'package:pdf_signature/ui/features/pdf/view_model/view_model.dart';
 import '_world.dart';
 
 /// Usage: the user attempts to save

test/features/step/the_user_can_apply_or_reset_adjustments.dart

@@ -1,6 +1,6 @@
 import 'package:flutter_test/flutter_test.dart';
 import 'package:flutter_riverpod/flutter_riverpod.dart';
-import 'package:pdf_signature/features/pdf/viewer.dart';
+import 'package:pdf_signature/ui/features/pdf/view_model/view_model.dart';
 import '_world.dart';
 
 /// Usage: the user can apply or reset adjustments

test/features/step/the_user_can_move_to_the_next_or_previous_page.dart

@@ -1,6 +1,6 @@
 import 'package:flutter_test/flutter_test.dart';
 import 'package:flutter_riverpod/flutter_riverpod.dart';
-import 'package:pdf_signature/features/pdf/viewer.dart';
+import 'package:pdf_signature/ui/features/pdf/view_model/view_model.dart';
 import '_world.dart';
 
 /// Usage: the user can move to the next or previous page

test/features/step/the_user_changes_contrast_and_brightness_controls.dart

@@ -1,6 +1,6 @@
 import 'package:flutter_test/flutter_test.dart';
 import 'package:flutter_riverpod/flutter_riverpod.dart';
-import 'package:pdf_signature/features/pdf/viewer.dart';
+import 'package:pdf_signature/ui/features/pdf/view_model/view_model.dart';
 import '_world.dart';
 
 /// Usage: the user changes contrast and brightness controls

test/features/step/the_user_chooses_a_signature_image_file.dart

@@ -1,7 +1,7 @@
 import 'dart:typed_data';
 import 'package:flutter_test/flutter_test.dart';
 import 'package:flutter_riverpod/flutter_riverpod.dart';
-import 'package:pdf_signature/features/pdf/viewer.dart';
+import 'package:pdf_signature/ui/features/pdf/view_model/view_model.dart';
 import '_world.dart';
 
 /// Usage: the user chooses a signature image file

test/features/step/the_user_chooses_undo.dart

@@ -1,6 +1,6 @@
 import 'package:flutter_test/flutter_test.dart';
 import 'package:flutter_riverpod/flutter_riverpod.dart';
-import 'package:pdf_signature/features/pdf/viewer.dart';
+import 'package:pdf_signature/ui/features/pdf/view_model/view_model.dart';
 import '_world.dart';
 
 /// Usage: the user chooses undo

test/features/step/the_user_clears_the_canvas.dart

@@ -1,6 +1,6 @@
 import 'package:flutter_test/flutter_test.dart';
 import 'package:flutter_riverpod/flutter_riverpod.dart';
-import 'package:pdf_signature/features/pdf/viewer.dart';
+import 'package:pdf_signature/ui/features/pdf/view_model/view_model.dart';
 import '_world.dart';
 
 /// Usage: the user clears the canvas

test/features/step/the_user_drags_handles_to_resize_and_drags_to_reposition.dart

@@ -1,6 +1,6 @@
 import 'package:flutter_test/flutter_test.dart';
 import 'package:flutter_riverpod/flutter_riverpod.dart';
-import 'package:pdf_signature/features/pdf/viewer.dart';
+import 'package:pdf_signature/ui/features/pdf/view_model/view_model.dart';
 import '_world.dart';
 
 /// Usage: the user drags handles to resize and drags to reposition

test/features/step/the_user_draws_strokes_and_confirms.dart

@@ -1,7 +1,7 @@
 import 'dart:typed_data';
 import 'package:flutter_test/flutter_test.dart';
 import 'package:flutter_riverpod/flutter_riverpod.dart';
-import 'package:pdf_signature/features/pdf/viewer.dart';
+import 'package:pdf_signature/ui/features/pdf/view_model/view_model.dart';
 import '_world.dart';
 
 /// Usage: the user draws strokes and confirms

test/features/step/the_user_enables_aspect_ratio_lock_and_resizes.dart

@@ -1,6 +1,6 @@
 import 'package:flutter_test/flutter_test.dart';
 import 'package:flutter_riverpod/flutter_riverpod.dart';
-import 'package:pdf_signature/features/pdf/viewer.dart';
+import 'package:pdf_signature/ui/features/pdf/view_model/view_model.dart';
 import '_world.dart';
 
 /// Usage: the user enables aspect ratio lock and resizes

test/features/step/the_user_enables_background_removal.dart

@@ -1,6 +1,6 @@
 import 'package:flutter_test/flutter_test.dart';
 import 'package:flutter_riverpod/flutter_riverpod.dart';
-import 'package:pdf_signature/features/pdf/viewer.dart';
+import 'package:pdf_signature/ui/features/pdf/view_model/view_model.dart';
 import '_world.dart';
 
 /// Usage: the user enables background removal

test/features/step/the_user_is_notified_of_the_issue.dart

@@ -1,6 +1,6 @@
 import 'package:flutter_test/flutter_test.dart';
 import 'package:flutter_riverpod/flutter_riverpod.dart';
-import 'package:pdf_signature/features/pdf/viewer.dart';
+import 'package:pdf_signature/ui/features/pdf/view_model/view_model.dart';
 import '_world.dart';
 
 /// Usage: the user is notified of the issue

test/features/step/the_user_savesexports_the_document.dart

@@ -1,7 +1,7 @@
 import 'dart:typed_data';
 import 'package:flutter_test/flutter_test.dart';
 import 'package:flutter_riverpod/flutter_riverpod.dart';
-import 'package:pdf_signature/features/pdf/viewer.dart';
+import 'package:pdf_signature/ui/features/pdf/view_model/view_model.dart';
 import '_world.dart';
 
 /// Usage: the user saves/exports the document

test/features/step/the_user_selects.dart

@@ -1,6 +1,6 @@
 import 'package:flutter_test/flutter_test.dart';
 import 'package:flutter_riverpod/flutter_riverpod.dart';
-import 'package:pdf_signature/features/pdf/viewer.dart';
+import 'package:pdf_signature/ui/features/pdf/view_model/view_model.dart';
 import '_world.dart';
 
 /// Usage: the user selects "<file>"

test/features/step/the_user_selects_a_specific_page_number.dart

@@ -1,6 +1,6 @@
 import 'package:flutter_test/flutter_test.dart';
 import 'package:flutter_riverpod/flutter_riverpod.dart';
-import 'package:pdf_signature/features/pdf/viewer.dart';
+import 'package:pdf_signature/ui/features/pdf/view_model/view_model.dart';
 import '_world.dart';
 
 /// Usage: the user selects a specific page number

test/pdf_state_test.dart

@@ -1,5 +1,5 @@
 import 'package:flutter_test/flutter_test.dart';
-import 'package:pdf_signature/features/pdf/viewer.dart';
+import 'package:pdf_signature/ui/features/pdf/view_model/view_model.dart';
 import 'package:flutter_riverpod/flutter_riverpod.dart';
 
 void main() {

test/signature_state_test.dart

@@ -2,7 +2,7 @@ import 'dart:typed_data';
 
 import 'package:flutter_riverpod/flutter_riverpod.dart';
 import 'package:flutter_test/flutter_test.dart';
-import 'package:pdf_signature/features/pdf/viewer.dart';
+import 'package:pdf_signature/ui/features/pdf/view_model/view_model.dart';
 
 void main() {
   test('placeDefaultRect centers a reasonable default rect', () {

test/widget/widget_test.dart

@@ -11,8 +11,12 @@ import 'package:flutter_riverpod/flutter_riverpod.dart';
 import 'dart:typed_data';
 import 'dart:ui' show PointerDeviceKind;
 
-import 'package:pdf_signature/features/pdf/viewer.dart';
-import 'package:pdf_signature/features/share/export_service.dart';
+import 'package:pdf_signature/ui/features/pdf/view_model/view_model.dart';
+import 'package:pdf_signature/data/services/providers.dart';
+import 'package:pdf_signature/ui/features/pdf/widgets/pdf_screen.dart';
+import 'package:pdf_signature/ui/features/pdf/widgets/draw_canvas.dart';
+
+import 'package:pdf_signature/data/services/export_service.dart';
 import 'package:hand_signature/signature.dart' as hand;
 
 // Fakes for export service (top-level; Dart does not allow local class declarations)