Source Code added

mobile/lib/providers/image/immich_local_thumbnail_provider.dart

@@ -0,0 +1,88 @@
+import 'dart:async';
+import 'dart:ui' as ui;
+
+import 'package:cached_network_image/cached_network_image.dart';
+import 'package:flutter_cache_manager/flutter_cache_manager.dart';
+import 'package:immich_mobile/providers/image/cache/thumbnail_image_cache_manager.dart';
+
+import 'package:flutter/foundation.dart';
+import 'package:flutter/painting.dart';
+import 'package:immich_mobile/entities/asset.entity.dart';
+import 'package:photo_manager/photo_manager.dart' show ThumbnailSize;
+import 'package:logging/logging.dart';
+
+/// The local image provider for an asset
+/// Only viable
+class ImmichLocalThumbnailProvider extends ImageProvider<ImmichLocalThumbnailProvider> {
+  final Asset asset;
+  final int height;
+  final int width;
+  final CacheManager? cacheManager;
+  final Logger log = Logger("ImmichLocalThumbnailProvider");
+  final String? userId;
+
+  ImmichLocalThumbnailProvider({
+    required this.asset,
+    this.height = 256,
+    this.width = 256,
+    this.cacheManager,
+    this.userId,
+  }) : assert(asset.local != null, 'Only usable when asset.local is set');
+
+  /// Converts an [ImageProvider]'s settings plus an [ImageConfiguration] to a key
+  /// that describes the precise image to load.
+  @override
+  Future<ImmichLocalThumbnailProvider> obtainKey(ImageConfiguration configuration) {
+    return SynchronousFuture(this);
+  }
+
+  @override
+  ImageStreamCompleter loadImage(ImmichLocalThumbnailProvider key, ImageDecoderCallback decode) {
+    final cache = cacheManager ?? ThumbnailImageCacheManager();
+    return MultiImageStreamCompleter(
+      codec: _codec(key.asset, cache, decode),
+      scale: 1.0,
+      informationCollector: () sync* {
+        yield ErrorDescription(key.asset.fileName);
+      },
+    );
+  }
+
+  // Streams in each stage of the image as we ask for it
+  Stream<ui.Codec> _codec(Asset assetData, CacheManager cache, ImageDecoderCallback decode) async* {
+    final cacheKey = '$userId${assetData.localId}${assetData.checksum}$width$height';
+    final fileFromCache = await cache.getFileFromCache(cacheKey);
+    if (fileFromCache != null) {
+      try {
+        final buffer = await ui.ImmutableBuffer.fromFilePath(fileFromCache.file.path);
+        final codec = await decode(buffer);
+        yield codec;
+        return;
+      } catch (error) {
+        log.severe('Found thumbnail in cache, but loading it failed', error);
+      }
+    }
+
+    final thumbnailBytes = await assetData.local?.thumbnailDataWithSize(ThumbnailSize(width, height), quality: 80);
+    if (thumbnailBytes == null) {
+      throw StateError("Loading thumb for local photo ${assetData.fileName} failed");
+    }
+
+    final buffer = await ui.ImmutableBuffer.fromUint8List(thumbnailBytes);
+    final codec = await decode(buffer);
+    yield codec;
+    await cache.putFile(cacheKey, thumbnailBytes);
+  }
+
+  @override
+  bool operator ==(Object other) {
+    if (identical(this, other)) return true;
+    if (other is ImmichLocalThumbnailProvider) {
+      return asset.id == other.asset.id && asset.localId == other.asset.localId;
+    }
+    return false;
+  }
+
+  @override
+  int get hashCode => Object.hash(asset.id, asset.localId);
+}