immich/mobile/lib/presentation/widgets/images/thumb_hash_provider.dart

import 'package:flutter/foundation.dart';
import 'package:flutter/rendering.dart';
import 'package:immich_mobile/infrastructure/repositories/asset_media.repository.dart';
import 'package:immich_mobile/presentation/widgets/images/image_provider.dart';
import 'package:immich_mobile/presentation/widgets/images/one_frame_multi_image_stream_completer.dart';

class ThumbHashProvider extends ImageProvider<ThumbHashProvider> with CancellableImageProviderMixin {
  final String thumbHash;

  ThumbHashProvider({required this.thumbHash});

  @override
  Future<ThumbHashProvider> obtainKey(ImageConfiguration configuration) {
    return SynchronousFuture(this);
  }

  @override
  ImageStreamCompleter loadImage(ThumbHashProvider key, ImageDecoderCallback decode) {
    final completer = OneFramePlaceholderImageStreamCompleter(_loadCodec(key, decode));
    completer.addOnLastListenerRemovedCallback(cancel);
    return completer;
  }

  Stream<ImageInfo> _loadCodec(ThumbHashProvider key, ImageDecoderCallback decode) async* {
    final request = this.request = ThumbhashImageRequest(thumbhash: thumbHash);
    try {
      final image = await request.load(decode);
      if (image != null) {
        yield image;
      }
    } finally {
      this.request = null;
    }
  }

  @override
  bool operator ==(Object other) {
    if (identical(this, other)) return true;
    if (other is ThumbHashProvider) {
      return thumbHash == other.thumbHash;
    }
    return false;
  }

  @override
  int get hashCode => thumbHash.hashCode;
}