fix(mobile): clamp preview targets to a minimum of one pixel

mobile/ios/Runner/Images/LocalImagesImpl.swift

@@ -20,6 +20,7 @@ class LocalImageApiImpl: LocalImageApi {
     requestOptions.version = .current
     return requestOptions
   }()
+  private static let maxPixelSize: CGFloat = 16384
 
   private static let registry = RequestRegistry<ImageRequest>()
 
@@ -108,11 +109,16 @@ class LocalImageApiImpl: LocalImageApi {
         ]))
       }
 
+      let isOriginal = !(width > 0 && height > 0)
+      let targetSize = isOriginal
+        ? CGSize(width: Self.maxPixelSize, height: Self.maxPixelSize)
+        : CGSize(width: Double(width), height: Double(height))
+      let contentMode: PHImageContentMode = isOriginal ? .aspectFit : .aspectFill
       var image: UIImage?
       Self.imageManager.requestImage(
         for: asset,
-        targetSize: width > 0 && height > 0 ? CGSize(width: Double(width), height: Double(height)) : PHImageManagerMaximumSize,
-        contentMode: .aspectFill,
+        targetSize: targetSize,
+        contentMode: contentMode,
         options: Self.requestOptions,
         resultHandler: { (_image, info) -> Void in
           image = _image
@@ -123,12 +129,38 @@ class LocalImageApiImpl: LocalImageApi {
         return request.completion(ImageProcessing.cancelledResult)
       }
 
-      guard let image = image,
-            let cgImage = image.cgImage else {
+      guard let fastImage = image,
+            var cgImage = fastImage.cgImage else {
         Self.registry.remove(requestId: requestId)
         return request.completion(.failure(PigeonError(code: "", message: "Could not get pixel data for \(assetId)", details: nil)))
       }
 
+      // .fast can return larger than the target, so retry with .exact to guarantee the bound.
+      if max(cgImage.width, cgImage.height) > Int(Self.maxPixelSize) {
+        let exactOptions = Self.requestOptions.copy() as! PHImageRequestOptions
+        exactOptions.resizeMode = .exact
+        image = nil
+        Self.imageManager.requestImage(
+          for: asset,
+          targetSize: targetSize,
+          contentMode: contentMode,
+          options: exactOptions,
+          resultHandler: { (_image, info) -> Void in
+            image = _image
+          }
+        )
+
+        if request.isCancelled {
+          return request.completion(ImageProcessing.cancelledResult)
+        }
+
+        guard let exactImage = image?.cgImage else {
+          Self.registry.remove(requestId: requestId)
+          return request.completion(.failure(PigeonError(code: "", message: "Could not resize image for \(assetId)", details: nil)))
+        }
+        cgImage = exactImage
+      }
+
       if request.isCancelled {
         return request.completion(ImageProcessing.cancelledResult)
       }

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';
 
+// iOS GPU textures max out at 16384px; larger images squish.
+const _kMaxPixelSize = 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);
+
+  // Use an aspect-correct target when aspectFill would exceed the texture limit.
+  @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 <= _kMaxPixelSize) {
+      return Size(boxW, boxH);
+    }
+    final bound = previewIsFinal ? _kMaxPixelSize.toDouble() : math.max(boxW, boxH);
+    final scale = math.min(1.0, bound / imgLong);
+    return Size(math.max(1.0, width * scale), math.max(1.0, 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 +1,54 @@
+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', () {
+    const box = Size(1179, 2556);
+    const cases = <(String, Size, int?, int?, bool, Size)>[
+      ('normal', box, 4032, 3024, true, box),
+      ('missing dimensions', box, null, null, true, box),
+      ('invalid dimensions', box, 1000, 0, true, box),
+      ('long final preview', box, 1000, 30000, true, Size(16384 / 30, 16384)),
+      ('long first preview', box, 30000, 1000, false, Size(2556, 2556 / 30)),
+      ('ultra-thin preview', box, 10, 50000, false, Size(1, 2556)),
+      ('small source', box, 50, 2000, true, Size(50, 2000)),
+      ('at limit', Size(16384, 100), 1000, 1000, true, Size(16384, 100)),
+      ('over limit', Size(16385, 100), 1000, 1000, true, Size(1000, 1000)),
+    ];
+
+    for (final (name, box, width, height, previewIsFinal, expected) in cases) {
+      test(name, () {
+        final actual = LocalFullImageProvider.previewTargetSize(
+          box.width,
+          box.height,
+          width,
+          height,
+          previewIsFinal: previewIsFinal,
+        );
+        expect(actual.width, closeTo(expected.width, 1e-6));
+        expect(actual.height, closeTo(expected.height, 1e-6));
+      });
+    }
+  });
+
+  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('uses dimensions in the cache key', () {
+      final a = make(width: 100, height: 200);
+      final b = make(width: 100, height: 200);
+      expect(a, b);
+      expect(a.hashCode, b.hashCode);
+      expect(a == make(width: 200, height: 100), isFalse);
+    });
+  });
+}