CachedNetworkImageWidget/lib/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:network_image_cached/src/http_request.dart';

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

class CachedNetworkImageWidget extends StatelessWidget {
  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? cachkey;
  final Widget? loadwidget;

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

  @override
  Widget build(BuildContext context) {
    return BlocProvider(
      create: (context) => CashedImageBloc()
        ..add(
          GetStartImageEvent(
            url: imageUrl,
            cached: cached,
            count: count,
            cachkey: cachkey,
          ),
        ),
      child: Builder(
        builder: (context) {
          return BlocBuilder<CashedImageBloc, CashedImageState>(
            builder: (context, state) {
              if (state is CashedImageGetErrorState) {
                return SizedBox(
                  width: width,
                  height: height,
                  child: errorWidget ?? Center(child: Icon(Icons.error)),
                );
              }

              if (state is CashedImageGetState) {
                return Image.memory(
                  state.bytes,
                  fit: fit,
                  width: width,
                  height: height,
                );
              }
              return SizedBox(
                width: width,
                height: height,
                child:
                    placeholder ?? Center(child: 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? cachkey;
  final Widget? loadwidget;

  const CachedNetworkImageProvider({
    required this.imageUrl,
    required this.cachkey,
    required this.fit,
    this.count = 10,
    this.height,
    this.width,
    this.errorWidget,
    this.placeholder,
    this.cached = true,
    this.loadwidget = const CircularProgressIndicator(),
  });

  @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);
      // 2. Декодируем байты в ui.Image

      Uint8List img = await httpGetImage.getDataObjectIsolate();
      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);
  }
}