fix(mobile): fix squished long image previews on ios

mobile/ios/Runner/Images/LocalImagesImpl.swift

@@ -20,6 +20,7 @@ class LocalImageApiImpl: LocalImageApi {
     requestOptions.version = .current
     return requestOptions
   }()
+  private static let maxOriginalPixelSize: CGFloat = 16384
 
   private static let registry = RequestRegistry<ImageRequest>()
 
@@ -108,11 +109,18 @@ class LocalImageApiImpl: LocalImageApi {
         ]))
       }
 
+      // PHImageManagerMaximumSize returns a distorted aspect ratio for images too large to render
+      // (extreme panoramas / long screenshots). Bound the long edge to 16384 (the GPU max texture
+      // size) with aspectFit so the true ratio is kept and the buffer stays renderable. .fast resize
+      // is enough, we only need the long edge under the limit.
+      let isOriginal = !(width > 0 && height > 0)
       var image: UIImage?
       Self.imageManager.requestImage(
         for: asset,
-        targetSize: width > 0 && height > 0 ? CGSize(width: Double(width), height: Double(height)) : PHImageManagerMaximumSize,
-        contentMode: .aspectFill,
+        targetSize: isOriginal
+          ? CGSize(width: Self.maxOriginalPixelSize, height: Self.maxOriginalPixelSize)
+          : CGSize(width: Double(width), height: Double(height)),
+        contentMode: isOriginal ? .aspectFit : .aspectFill,
         options: Self.requestOptions,
         resultHandler: { (_image, info) -> Void in
           image = _image

mobile/lib/presentation/widgets/images/image_provider.dart

@@ -159,7 +159,14 @@ ImageProvider getFullImageProvider(
     provider = FileImage(File(localFilePath));
   } else if (_shouldUseLocalAsset(asset)) {
     final id = asset is LocalAsset ? asset.id : (asset as RemoteAsset).localId!;
-    provider = LocalFullImageProvider(id: id, size: size, assetType: asset.type, isAnimated: asset.isAnimatedImage);
+    provider = LocalFullImageProvider(
+      id: id,
+      size: size,
+      assetType: asset.type,
+      isAnimated: asset.isAnimatedImage,
+      width: asset.width,
+      height: asset.height,
+    );
   } else {
     final String assetId;
     final String thumbhash;

mobile/lib/presentation/widgets/images/local_image_provider.dart

@@ -1,3 +1,5 @@
+import 'dart:math' as math;
+
 import 'package:flutter/foundation.dart';
 import 'package:flutter/widgets.dart';
 import 'package:immich_mobile/domain/models/asset/base_asset.model.dart';
@@ -8,6 +10,9 @@ import 'package:immich_mobile/presentation/widgets/images/image_provider.dart';
 import 'package:immich_mobile/presentation/widgets/images/one_frame_multi_image_stream_completer.dart';
 import 'package:immich_mobile/presentation/widgets/timeline/constants.dart';
 
+// iphone's max gpu texture size. images longer than this squish in the preview.
+const _kMaxTextureSize = 16384;
+
 class LocalThumbProvider extends CancellableImageProvider<LocalThumbProvider>
     with CancellableImageProviderMixin<LocalThumbProvider> {
   final String id;
@@ -59,8 +64,36 @@ class LocalFullImageProvider extends CancellableImageProvider<LocalFullImageProv
   final Size size;
   final AssetType assetType;
   final bool isAnimated;
+  final int? width;
+  final int? height;
 
-  LocalFullImageProvider({required this.id, required this.assetType, required this.size, required this.isAnimated});
+  LocalFullImageProvider({
+    required this.id,
+    required this.assetType,
+    required this.size,
+    required this.isAnimated,
+    this.width,
+    this.height,
+  });
+
+  Size _previewTarget(double dpr, bool previewIsFinal) =>
+      previewTargetSize(size.width * dpr, size.height * dpr, width, height, previewIsFinal: previewIsFinal);
+
+  // long images squish on aspectFill; use an aspect-correct target (full detail if final, else light).
+  @visibleForTesting
+  static Size previewTargetSize(double boxW, double boxH, int? width, int? height, {required bool previewIsFinal}) {
+    if (width == null || height == null || width <= 0 || height <= 0) {
+      return Size(boxW, boxH);
+    }
+    final imgLong = math.max(width, height).toDouble();
+    final coverLong = imgLong * math.max(boxW / width, boxH / height);
+    if (coverLong <= _kMaxTextureSize) {
+      return Size(boxW, boxH);
+    }
+    final bound = previewIsFinal ? _kMaxTextureSize.toDouble() : math.max(boxW, boxH);
+    final scale = math.min(1.0, bound / imgLong);
+    return Size(width * scale, height * scale);
+  }
 
   @override
   Future<LocalFullImageProvider> obtainKey(ImageConfiguration configuration) {
@@ -108,7 +141,7 @@ class LocalFullImageProvider extends CancellableImageProvider<LocalFullImageProv
     final devicePixelRatio = PlatformDispatcher.instance.views.first.devicePixelRatio;
     var request = this.request = LocalImageRequest(
       localId: key.id,
-      size: Size(size.width * devicePixelRatio, size.height * devicePixelRatio),
+      size: _previewTarget(devicePixelRatio, !loadOriginal),
       assetType: key.assetType,
     );
     yield* loadRequest(request, decode, isFinal: !loadOriginal);
@@ -136,7 +169,7 @@ class LocalFullImageProvider extends CancellableImageProvider<LocalFullImageProv
     final devicePixelRatio = PlatformDispatcher.instance.views.first.devicePixelRatio;
     final previewRequest = request = LocalImageRequest(
       localId: key.id,
-      size: Size(size.width * devicePixelRatio, size.height * devicePixelRatio),
+      size: _previewTarget(devicePixelRatio, false),
       assetType: key.assetType,
     );
     yield* loadRequest(previewRequest, decode, isFinal: false);
@@ -163,11 +196,15 @@ class LocalFullImageProvider extends CancellableImageProvider<LocalFullImageProv
       return true;
     }
     if (other is LocalFullImageProvider) {
-      return id == other.id && size == other.size && isAnimated == other.isAnimated;
+      return id == other.id &&
+          size == other.size &&
+          isAnimated == other.isAnimated &&
+          width == other.width &&
+          height == other.height;
     }
     return false;
   }
 
   @override
-  int get hashCode => id.hashCode ^ size.hashCode ^ isAnimated.hashCode;
+  int get hashCode => id.hashCode ^ size.hashCode ^ isAnimated.hashCode ^ width.hashCode ^ height.hashCode;
 }

mobile/test/presentation/widgets/images/local_image_provider_test.dart

@@ -0,0 +1,92 @@
+import 'package:flutter/widgets.dart';
+import 'package:flutter_test/flutter_test.dart';
+import 'package:immich_mobile/domain/models/asset/base_asset.model.dart';
+import 'package:immich_mobile/presentation/widgets/images/local_image_provider.dart';
+
+void main() {
+  group('LocalFullImageProvider.previewTargetSize', () {
+    // a typical phone preview box (logical size * devicePixelRatio).
+    const boxW = 1179.0;
+    const boxH = 2556.0;
+    const oldBox = Size(boxW, boxH);
+
+    test('normal landscape keeps the exact old box (no preview regression)', () {
+      // 4:3, cover long edge ~3407 < 16384 -> not gated, regardless of previewIsFinal.
+      expect(LocalFullImageProvider.previewTargetSize(boxW, boxH, 4032, 3024, previewIsFinal: true), oldBox);
+      expect(LocalFullImageProvider.previewTargetSize(boxW, boxH, 4032, 3024, previewIsFinal: false), oldBox);
+    });
+
+    test('normal portrait keeps the exact old box', () {
+      expect(LocalFullImageProvider.previewTargetSize(boxW, boxH, 3024, 4032, previewIsFinal: true), oldBox);
+    });
+
+    test('null or zero dims fall back to the old box', () {
+      expect(LocalFullImageProvider.previewTargetSize(boxW, boxH, null, null, previewIsFinal: true), oldBox);
+      expect(LocalFullImageProvider.previewTargetSize(boxW, boxH, 0, 0, previewIsFinal: true), oldBox);
+      expect(LocalFullImageProvider.previewTargetSize(boxW, boxH, 1000, 0, previewIsFinal: true), oldBox);
+    });
+
+    test('extreme panorama, FINAL preview (load-original off): capped at the texture limit, ratio kept', () {
+      final t = LocalFullImageProvider.previewTargetSize(boxW, boxH, 1000, 30000, previewIsFinal: true);
+      expect(t, isNot(oldBox));
+      expect(t.longestSide, closeTo(16384, 1));
+      expect(t.width / t.height, closeTo(1000 / 30000, 1e-6));
+    });
+
+    test('extreme panorama, NON-final preview (load-original on): light, capped at screen long edge, ratio kept', () {
+      final t = LocalFullImageProvider.previewTargetSize(boxW, boxH, 1000, 30000, previewIsFinal: false);
+      expect(t, isNot(oldBox));
+      expect(t.longestSide, closeTo(boxH, 1)); // screen long edge = max(boxW, boxH), the original follows at 16384
+      expect(t.width / t.height, closeTo(1000 / 30000, 1e-6));
+    });
+
+    test('extreme but small source is never upscaled', () {
+      // ratio 40 -> gated, but the source long edge (2000) < texture limit so scale clamps to 1.0.
+      expect(
+        LocalFullImageProvider.previewTargetSize(boxW, boxH, 50, 2000, previewIsFinal: true),
+        const Size(50, 2000),
+      );
+    });
+
+    test('narrow image is gated in but not upscaled (long edge already under the texture limit)', () {
+      // ratio 100: cover overshoots 16384 so it's gated, but the source long edge (10000) < 16384 -> scale clamps to 1.0.
+      expect(
+        LocalFullImageProvider.previewTargetSize(boxW, boxH, 100, 10000, previewIsFinal: true),
+        const Size(100, 10000),
+      );
+    });
+
+    test('gate boundary: at the texture limit keeps the old box, just over switches to the fix', () {
+      // square source -> coverLong == the box long edge.
+      expect(
+        LocalFullImageProvider.previewTargetSize(16384, 100, 1000, 1000, previewIsFinal: true),
+        const Size(16384, 100),
+      );
+      final over = LocalFullImageProvider.previewTargetSize(16385, 100, 1000, 1000, previewIsFinal: true);
+      expect(over, isNot(const Size(16385, 100)));
+      expect(over, const Size(1000, 1000));
+    });
+  });
+
+  group('LocalFullImageProvider equality', () {
+    LocalFullImageProvider make({int? width, int? height}) => LocalFullImageProvider(
+      id: 'a',
+      assetType: AssetType.image,
+      size: const Size(100, 200),
+      isAnimated: false,
+      width: width,
+      height: height,
+    );
+
+    test('same id/size/isAnimated but different w/h are not equal (distinct cache entries)', () {
+      expect(make(width: 1000, height: 30000) == make(width: 4032, height: 3024), isFalse);
+    });
+
+    test('identical config is equal and shares a hashCode', () {
+      final a = make(width: 100, height: 200);
+      final b = make(width: 100, height: 200);
+      expect(a, b);
+      expect(a.hashCode, b.hashCode);
+    });
+  });
+}