CachedNetworkImageWidget/lib/src/CashedNetworkImageWidget.dart

import 'dart:ui' as ui;
import 'dart:ui';
import 'package:flutter/foundation.dart';
import 'package:flutter/material.dart';

import 'package:flutter_bloc/flutter_bloc.dart';
import 'package:flutter_cache_manager/flutter_cache_manager.dart';
import 'package:network_image_cached/src/http_request.dart';

import 'bloc/cashed_image_bloc.dart'
    show
        CashedImageBloc,
        CashedImageGetErrorState,
        CashedImageGetState,
        CashedImageState,
        GetStartImageEvent;

typedef ImageWidgetBuilder =
    Widget Function(BuildContext context, ImageProvider imageProvider);

class CachedNetworkImageWidget extends StatefulWidget {
  final String imageUrl;
  final int count;
  final double? width;
  final double? height;
  final Widget? placeholder;
  final Widget? errorWidget;
  final bool cached;
  final Map<String, String>? httpHeaders;
  final String? cacheKey;
  final Widget? loadwidget;
  final ImageWidgetBuilder imageBuilder;

  const CachedNetworkImageWidget({
    super.key,
    required this.imageUrl,
    required this.cacheKey,
    this.count = 10,
    this.height,
    this.width,
    this.errorWidget,
    this.placeholder,
    this.cached = true,
    this.loadwidget = const CircularProgressIndicator(),
    this.httpHeaders,
    required this.imageBuilder,
  });

  @override
  CachedNetworkImageWidgetState createState() =>
      CachedNetworkImageWidgetState();
}

class CachedNetworkImageWidgetState extends State<CachedNetworkImageWidget>
    with AutomaticKeepAliveClientMixin {
  late final CashedImageBloc bloc;

  @override
  void initState() {
    if (!mounted) {
      bloc = CashedImageBloc()
        ..add(
          GetStartImageEvent(
            httpHeaders: widget.httpHeaders,
            url: widget.imageUrl,
            cached: widget.cached,
            count: widget.count,
            cachkey: widget.cacheKey,
          ),
        );
    }
    super.initState();
  }

  @override
  void dispose() {
    bloc.close();
    super.dispose();
  }

  @override
  bool get wantKeepAlive => true;

  @override
  Widget build(BuildContext context) {
    super.build(context);

    return BlocProvider(
      create: (context) => bloc,
      child: BlocBuilder<CashedImageBloc, CashedImageState>(
        builder: (context, state) {
          if (state is CashedImageGetErrorState) {
            return SizedBox(
              width: widget.width,
              height: widget.height,
              child: widget.errorWidget ?? Center(child: Icon(Icons.error)),
            );
          }

          if (state is CashedImageGetState) {
            ImageProvider imageProvider = MemoryImage(state.bytes);
            return widget.imageBuilder(context, imageProvider!);
          }
          return SizedBox(
            width: widget.width,
            height: widget.height,
            child:
                widget.placeholder ??
                Center(child: widget.loadwidget ?? CircularProgressIndicator()),
          );
        },
      ),
    );
  }
}

class CachedNetworkImageProvider
    extends ImageProvider<CachedNetworkImageProvider> {
  final String imageUrl;
  final int count;
  final BoxFit fit;
  final double? width;
  final double? height;
  final Widget? placeholder;
  final Widget? errorWidget;
  final bool cached;
  final String? cacheKey;
  final Widget? loadwidget;
  final Map<String, String>? httpHeaders;
  const CachedNetworkImageProvider({
    required this.imageUrl,
    required this.cacheKey,
    required this.fit,
    this.count = 10,
    this.height,
    this.width,
    this.errorWidget,
    this.placeholder,
    this.cached = true,
    this.loadwidget = const CircularProgressIndicator(),
    this.httpHeaders,
  });

  @override
  ImageStreamCompleter loadImage(
    CachedNetworkImageProvider key,
    ImageDecoderCallback decode,
  ) {
    // 1. Создаём Future, который загрузит и декодирует изображение

    // 2. Возвращаем ImageStreamCompleter, который управляет потоком загрузки
    return MultiFrameImageStreamCompleter(
      codec: _loadAndDecodeImage(decode),
      scale: 1.0,
      informationCollector: () => <DiagnosticsNode>[
        DiagnosticsProperty<CachedNetworkImageProvider>(
          'Image provider',
          key,
          showName: false,
        ),
      ],
    );
  }

  // Вспомогательный метод: загружает байты и декодирует в ui.Image
  Future<ui.Codec> _loadAndDecodeImage(ImageDecoderCallback decode) async {
    try {
      // 1. Отправляем HTTP‑запрос
      HttpGetImage httpGetImage = HttpGetImage(
        url: imageUrl,
        count: count,
        httpHeaders: httpHeaders,
      );
      // 2. Декодируем байты в ui.Image
      DefaultCacheManager defaultCacheManager = DefaultCacheManager();
      if (cached) {
        FileInfo? fileInfo;
        if (cacheKey != null) {
          fileInfo = await defaultCacheManager.getFileFromCache(cacheKey!);
        } else {
          fileInfo = await defaultCacheManager.getFileFromCache(imageUrl);
        }

        if (fileInfo != null) {
          final decodedImage = await decode(
            await ImmutableBuffer.fromUint8List(
              await fileInfo.file.readAsBytes(),
            ),
          );

          return decodedImage;
        }
      }
      Uint8List img;
      try {
        img = await httpGetImage.getDataObjectIsolate();
        if (cached) {
          if (cacheKey != null) {
            defaultCacheManager.putFile(cacheKey!, img);
          } else {
            defaultCacheManager.putFile(imageUrl, img);
          }
        }
      } catch (e) {
        throw Exception('Failed to load image: $e');
      }

      final decodedImage = await decode(
        await ImmutableBuffer.fromUint8List(img),
      );

      return decodedImage;
    } catch (e) {
      // Если ошибка — бросаем исключение (будет обработано в Image widget)
      throw Exception('Failed to load image: $e');
    }
  }

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