feat(mobile): image caching & viewer improvements (#4095)

mobile/lib/shared/cache/custom_image_cache.dart

@@ -0,0 +1,69 @@
+import 'package:flutter/painting.dart';
+
+import 'original_image_provider.dart';
+
+/// [ImageCache] that uses two caches for small and large images
+/// so that a single large image does not evict all small iamges
+final class CustomImageCache implements ImageCache {
+  final _small = ImageCache();
+  final _large = ImageCache();
+
+  @override
+  int get maximumSize => _small.maximumSize + _large.maximumSize;
+
+  @override
+  int get maximumSizeBytes => _small.maximumSizeBytes + _large.maximumSizeBytes;
+
+  @override
+  set maximumSize(int value) => _small.maximumSize = value;
+
+  @override
+  set maximumSizeBytes(int value) => _small.maximumSize = value;
+
+  @override
+  void clear() {
+    _small.clear();
+    _large.clear();
+  }
+
+  @override
+  void clearLiveImages() {
+    _small.clearLiveImages();
+    _large.clearLiveImages();
+  }
+
+  @override
+  bool containsKey(Object key) =>
+      (key is OriginalImageProvider ? _large : _small).containsKey(key);
+
+  @override
+  int get currentSize => _small.currentSize + _large.currentSize;
+
+  @override
+  int get currentSizeBytes => _small.currentSizeBytes + _large.currentSizeBytes;
+
+  @override
+  bool evict(Object key, {bool includeLive = true}) =>
+      (key is OriginalImageProvider ? _large : _small)
+          .evict(key, includeLive: includeLive);
+
+  @override
+  int get liveImageCount => _small.liveImageCount + _large.liveImageCount;
+
+  @override
+  int get pendingImageCount =>
+      _small.pendingImageCount + _large.pendingImageCount;
+
+  @override
+  ImageStreamCompleter? putIfAbsent(
+    Object key,
+    ImageStreamCompleter Function() loader, {
+    ImageErrorListener? onError,
+  }) =>
+      (key is OriginalImageProvider ? _large : _small)
+          .putIfAbsent(key, loader, onError: onError);
+
+  @override
+  ImageCacheStatus statusForKey(Object key) =>
+      (key is OriginalImageProvider ? _large : _small).statusForKey(key);
+}

mobile/lib/shared/cache/original_image_provider.dart

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+import 'dart:async';
+import 'dart:io';
+import 'dart:ui' as ui;
+
+import 'package:flutter/foundation.dart';
+import 'package:flutter/widgets.dart';
+import 'package:immich_mobile/shared/models/asset.dart';
+
+/// Loads the original image for local assets
+@immutable
+final class OriginalImageProvider extends ImageProvider<OriginalImageProvider> {
+  final Asset asset;
+
+  const OriginalImageProvider(this.asset);
+
+  @override
+  Future<OriginalImageProvider> obtainKey(ImageConfiguration configuration) =>
+      SynchronousFuture<OriginalImageProvider>(this);
+
+  @override
+  ImageStreamCompleter loadImage(
+    OriginalImageProvider key,
+    ImageDecoderCallback decode,
+  ) =>
+      MultiFrameImageStreamCompleter(
+        codec: _loadAsync(key, decode),
+        scale: 1.0,
+        informationCollector: () sync* {
+          yield ErrorDescription(asset.fileName);
+        },
+      );
+
+  Future<ui.Codec> _loadAsync(
+    OriginalImageProvider key,
+    ImageDecoderCallback decode,
+  ) async {
+    final ui.ImmutableBuffer buffer;
+    if (asset.isImage) {
+      final File? file = await asset.local?.originFile;
+      if (file == null) {
+        throw StateError("Opening file for asset ${asset.fileName} failed");
+      }
+      try {
+        buffer = await ui.ImmutableBuffer.fromFilePath(file.path);
+      } catch (error) {
+        throw StateError("Loading asset ${asset.fileName} failed");
+      }
+    } else {
+      final thumbBytes = await asset.local?.thumbnailData;
+      if (thumbBytes == null) {
+        throw StateError("Loading thumb for video ${asset.fileName} failed");
+      }
+      buffer = await ui.ImmutableBuffer.fromUint8List(thumbBytes);
+    }
+    try {
+      final codec = await decode(buffer);
+      debugPrint("Decoded image ${asset.fileName}");
+      return codec;
+    } catch (error) {
+      throw StateError("Decoding asset ${asset.fileName} failed");
+    }
+  }
+
+  @override
+  bool operator ==(Object other) {
+    if (other is! OriginalImageProvider) return false;
+    if (identical(this, other)) return true;
+    return asset == other.asset;
+  }
+
+  @override
+  int get hashCode => asset.hashCode;
+}

mobile/lib/shared/cache/widgets_binding.dart

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+import 'package:flutter/widgets.dart';
+
+import 'custom_image_cache.dart';
+
+final class ImmichWidgetsBinding extends WidgetsFlutterBinding {
+  @override
+  ImageCache createImageCache() => CustomImageCache();
+}