Restore web identity photo previews (#69)

frontend/app/lib/kyc/preview.dart

@@ -1,3 +1,5 @@
+import 'dart:typed_data';
+
 import 'package:flutter/material.dart';
 
 import 'package:sxchnge_kyc/sxchnge_kyc.dart';
@@ -15,8 +17,12 @@ class PhotoPreview extends StatefulWidget {
 
 class _PhotoPreviewState extends State<PhotoPreview> {
   late ImageProvider _image = _provider();
-  ImageProvider _provider() =>
-      ResizeImage.resizeIfNeeded(1000, null, MemoryImage(widget.photo.bytes));
+  ImageProvider _provider() => ResizeImage.resizeIfNeeded(
+    1000,
+    null,
+    // Web decoders require a native typed array, not the model's read-only view.
+    MemoryImage(Uint8List.fromList(widget.photo.bytes)),
+  );
   @override
   void didUpdateWidget(covariant PhotoPreview oldWidget) {
     super.didUpdateWidget(oldWidget);
@@ -38,7 +44,15 @@ class _PhotoPreviewState extends State<PhotoPreview> {
     height: 220,
     fit: BoxFit.contain,
     semanticLabel: widget.label,
-    errorBuilder: (_, _, _) =>
-        Text(AppLocalizations.of(context)!.kycErrorUnreadable),
+    errorBuilder: (_, _, _) => ConstrainedBox(
+      constraints: const BoxConstraints(minHeight: 220),
+      child: Center(
+        child: Semantics(
+          container: true,
+          liveRegion: true,
+          child: Text(AppLocalizations.of(context)!.kycErrorPreview),
+        ),
+      ),
+    ),
   );
 }

frontend/app/lib/l10n/en.arb

@@ -128,6 +128,7 @@
   "kycErrorFormat": "Choose a JPEG or PNG image. Other formats are not supported.",
   "kycErrorLarge": "This image is too large. Choose one under 10 MB and 40 megapixels.",
   "kycErrorUnreadable": "This image is damaged or cannot be read. Choose another photo.",
+  "kycErrorPreview": "The photo preview could not be displayed. Try choosing the photo again.",
   "kycErrorSmall": "The photo is too small. Use an image at least 600 pixels wide and high.",
   "kycErrorIncomplete": "Choose both photos and confirm they belong to you before submitting.",
   "kycErrorSession": "Your session has expired. Return to login, then check your verification status.",

frontend/app/lib/l10n/ru.arb

@@ -128,6 +128,7 @@
   "kycErrorFormat": "Выберите изображение JPEG или PNG. Другие форматы не поддерживаются.",
   "kycErrorLarge": "Изображение слишком большое. Выберите файл до 10 МБ и 40 мегапикселей.",
   "kycErrorUnreadable": "Изображение повреждено или не читается. Выберите другое фото.",
+  "kycErrorPreview": "Не удалось показать фото. Попробуйте выбрать его ещё раз.",
   "kycErrorSmall": "Фото слишком маленькое. Ширина и высота должны быть не менее 600 пикселей.",
   "kycErrorIncomplete": "Выберите оба фото и подтвердите, что на них вы и ваш документ.",
   "kycErrorSession": "Сессия истекла. Войдите снова и проверьте статус верификации.",

frontend/app/pubspec.lock

@@ -222,7 +222,7 @@ packages:
     source: hosted
     version: "4.1.2"
   image:
-    dependency: transitive
+    dependency: "direct dev"
     description:
       name: image
       sha256: "1976370a4df3091bb0f72409c187ad1f9132a818bc6b95ca59c0bae1c75c688e"

frontend/app/pubspec.yaml

@@ -29,6 +29,7 @@ dependencies:
   go_router: ^18.0.1
   country_picker: ^2.0.28
 dev_dependencies:
+  image: ^4.9.0
   flutter_test:
     sdk: flutter
   flutter_lints: ^6.0.0

frontend/app/test/preview_test.dart

@@ -0,0 +1,229 @@
+import 'dart:async';
+import 'dart:typed_data';
+
+import 'package:flutter/material.dart';
+
+import 'package:flutter_test/flutter_test.dart';
+
+import 'package:image/image.dart' as images;
+
+import 'package:sxchnge_kyc/sxchnge_kyc.dart';
+
+import 'package:sxchnge_app/kyc/photo.dart';
+import 'package:sxchnge_app/kyc/preview.dart';
+
+import 'package:sxchnge_app/generated/i18n/app_localizations.dart';
+
+Widget host(Widget child, {Locale locale = const Locale('en')}) => MaterialApp(
+  locale: locale,
+  localizationsDelegates: AppLocalizations.localizationsDelegates,
+  supportedLocales: AppLocalizations.supportedLocales,
+  home: Scaffold(body: SingleChildScrollView(child: child)),
+);
+
+// Start decoding outside FakeAsync as well as waiting outside it, including
+// browser codec callbacks that otherwise remain pending in the test zone.
+Future<void> show(WidgetTester tester, Widget widget) async {
+  await tester.runAsync(() => tester.pumpWidget(widget));
+}
+
+// pumpAndSettle alone does not wait for image codecs. Listen to the actual
+// preview streams so a hidden errorBuilder cannot make this regression pass.
+Future<void> decoded(WidgetTester tester, {bool succeeds = true}) async {
+  final providers = tester
+      .widgetList<Image>(find.byType(Image))
+      .map((image) => image.image)
+      .toList();
+  expect(providers, isNotEmpty);
+  for (final provider in providers) {
+    Object? renderError;
+    StackTrace? renderStack;
+    await tester.runAsync(() async {
+      final stream = provider.resolve(ImageConfiguration.empty);
+      final ready = Completer<void>();
+      final listener = ImageStreamListener(
+        (info, _) {
+          info.dispose();
+          if (!ready.isCompleted) ready.complete();
+        },
+        onError: (Object error, StackTrace? stack) {
+          renderError = error;
+          renderStack = stack;
+          if (!ready.isCompleted) ready.complete();
+        },
+      );
+      stream.addListener(listener);
+      try {
+        await ready.future.timeout(const Duration(seconds: 15));
+      } finally {
+        stream.removeListener(listener);
+      }
+    });
+    expect(
+      renderError,
+      succeeds ? isNull : isNotNull,
+      reason: succeeds ? '$renderError\n$renderStack' : null,
+    );
+  }
+  await tester.pumpAndSettle();
+  expect(tester.takeException(), isNull);
+}
+
+void main() {
+  late Uint8List png;
+  late Uint8List jpeg;
+  setUpAll(() {
+    // Synthetic, non-sensitive portrait and landscape photos in both formats.
+    png = images.encodePng(images.Image(width: 1200, height: 1600));
+    jpeg = images.encodeJpg(images.Image(width: 1600, height: 1200));
+  });
+
+  for (final format in ['PNG', 'JPEG']) {
+    testWidgets('accepted $format renders from an immutable photo model', (
+      tester,
+    ) async {
+      final source = Uint8List.fromList(format == 'PNG' ? png : jpeg);
+      final photo = (await tester.runAsync(
+        () => FilePhotoService.validate(source),
+      ))!;
+      final originalFirstByte = photo.bytes.first;
+      source[0] = 0;
+      expect(photo.bytes.first, originalFirstByte);
+      expect(() => photo.bytes[0] = 0, throwsUnsupportedError);
+      await show(
+        tester,
+        host(PhotoPreview(photo: photo, label: 'ID document photo')),
+      );
+      await decoded(tester);
+      final raw = tester.widget<RawImage>(find.byType(RawImage));
+      expect(raw.image, isNotNull);
+      expect(raw.image!.width, lessThanOrEqualTo(1000));
+      expect(
+        tester.widget<Image>(find.byType(Image)).semanticLabel,
+        'ID document photo',
+      );
+      expect(find.textContaining('damaged'), findsNothing);
+      expect(find.textContaining('could not be displayed'), findsNothing);
+    });
+  }
+
+  testWidgets('replacement and removal evict sensitive preview cache entries', (
+    tester,
+  ) async {
+    final first = Photo(png);
+    await show(tester, host(PhotoPreview(photo: first, label: 'ID')));
+    await decoded(tester);
+    final initialProvider = tester.widget<Image>(find.byType(Image)).image;
+    final initialKey = await initialProvider.obtainKey(
+      ImageConfiguration.empty,
+    );
+    final cache = PaintingBinding.instance.imageCache;
+    expect(cache.statusForKey(initialKey).keepAlive, isTrue);
+    await show(tester, host(PhotoPreview(photo: first, label: 'Document')));
+    await decoded(tester);
+    expect(
+      identical(
+        tester.widget<Image>(find.byType(Image)).image,
+        initialProvider,
+      ),
+      isTrue,
+    );
+    await show(tester, host(PhotoPreview(photo: Photo(jpeg), label: 'ID')));
+    await decoded(tester);
+    expect(cache.statusForKey(initialKey).untracked, isTrue);
+    final replacement = tester.widget<Image>(find.byType(Image)).image;
+    final replacementKey = await replacement.obtainKey(
+      ImageConfiguration.empty,
+    );
+    expect(cache.statusForKey(replacementKey).keepAlive, isTrue);
+    expect(tester.widget<RawImage>(find.byType(RawImage)).image!.width, 1000);
+    await show(tester, host(const SizedBox()));
+    await tester.pumpAndSettle();
+    expect(cache.statusForKey(replacementKey).untracked, isTrue);
+  });
+
+  testWidgets('ID and selfie both render on review and after returning', (
+    tester,
+  ) async {
+    final passport = Photo(png);
+    final selfie = Photo(jpeg);
+    for (var visit = 0; visit < 2; visit++) {
+      await show(
+        tester,
+        host(
+          Column(
+            children: [
+              PhotoPanel(
+                kind: PhotoKind.passport,
+                photo: passport,
+                review: true,
+              ),
+              PhotoPanel(kind: PhotoKind.selfie, photo: selfie, review: true),
+            ],
+          ),
+        ),
+      );
+      await decoded(tester);
+      final previews = tester.widgetList<RawImage>(find.byType(RawImage));
+      expect(previews.length, 2);
+      expect(previews.every((image) => image.image != null), isTrue);
+      expect(find.text('Choose a different photo'), findsNothing);
+      await show(tester, host(const SizedBox()));
+      await tester.pumpAndSettle();
+    }
+  });
+
+  for (final locale in ['en', 'ru']) {
+    testWidgets(
+      '$locale preview failure explains recovery and can be replaced',
+      (tester) async {
+        tester.view.physicalSize = const Size(320, 900);
+        tester.view.devicePixelRatio = 1;
+        tester.platformDispatcher.textScaleFactorTestValue = 1.6;
+        addTearDown(tester.view.resetPhysicalSize);
+        addTearDown(tester.view.resetDevicePixelRatio);
+        addTearDown(tester.platformDispatcher.clearTextScaleFactorTestValue);
+        var replacements = 0;
+        var removals = 0;
+        await show(
+          tester,
+          host(
+            PhotoPanel(
+              kind: PhotoKind.passport,
+              photo: Photo(Uint8List.fromList([1, 2, 3])),
+              onPick: () => replacements++,
+              onRemove: () => removals++,
+            ),
+            locale: Locale(locale),
+          ),
+        );
+        await decoded(tester, succeeds: false);
+        final l = AppLocalizations.of(tester.element(find.byType(PhotoPanel)))!;
+        expect(find.text(l.kycErrorPreview), findsOneWidget);
+        expect(find.text(l.kycErrorUnreadable), findsNothing);
+        expect(
+          tester.getSemantics(find.text(l.kycErrorPreview)),
+          matchesSemantics(isLiveRegion: true, label: l.kycErrorPreview),
+        );
+        final replace = find.byKey(const ValueKey('pick-passport'));
+        await tester.ensureVisible(replace);
+        await tester.tap(replace);
+        final remove = find.text(l.kycRemove);
+        await tester.ensureVisible(remove);
+        await tester.tap(remove);
+        expect(replacements, 1);
+        expect(removals, 1);
+        await show(
+          tester,
+          host(
+            PhotoPanel(kind: PhotoKind.passport, photo: Photo(jpeg)),
+            locale: Locale(locale),
+          ),
+        );
+        await decoded(tester);
+        expect(find.text(l.kycErrorPreview), findsNothing);
+        expect(tester.widget<RawImage>(find.byType(RawImage)).image, isNotNull);
+      },
+    );
+  }
+}