flutter - 'ImagePickerCubit' 不符合类型参数 'BlocBase' 的绑定(bind) 'B'

Question

我在尝试在我的应用程序中创建 BlocBuilder 时遇到错误:“'ImagePickerCubit' 不符合类型参数 'B' 的绑定(bind) 'BlocBase'。尝试使用属于或属于 'BlocBase' 的子类的类型。”

我是按照文档实现的，所以我不知道是什么原因导致了这个错误。

这里是 cubit、state 和 widgets 的代码:

ImagePickerCubit:

part 'image_picker_state.dart';

class ImagePickerCubit extends Cubit {
  final ImagePickerRepository _imagePickerRepository;

  ImagePickerCubit(this._imagePickerRepository)
      : super(ImagePickerInitialize());

  Future<void> takePhotoFromGallery() async {
    XFile? image;
    try {
      image = await _imagePickerRepository.takePhotoFromGallery();
      emit(ImagePickerSuccess(image));
    } catch (e) {
      emit(ImagePickerFailure('Error while picking image: ${e.toString()}'));
      log('Error while picking image from gallery: ${e.toString()}');
    }
  }

  Future<void> takePhotoFromCamera() async {
    XFile? image;
    try {
      image = await _imagePickerRepository.takePhotoFromCamera();
      emit(ImagePickerSuccess(image));
    } catch (e) {
      emit(ImagePickerFailure('Error while picking image: ${e.toString()}'));
      log('Error while picking image from camera: ${e.toString()}');
    }
  }
}

ImagePicker状态:

part of 'image_picker_cubit.dart';


class ImagePickerState extends Equatable {

  @override
  List<Object?> get props => [];
}

class ImagePickerInitialize extends ImagePickerState {}

class ImagePickerSuccess extends ImagePickerState {
  final XFile? image;
  ImagePickerSuccess(this.image);

  @override
  List<Object?> get props => [image];
}

class ImagePickerFailure extends ImagePickerState {
  final String errorMessage;
  ImagePickerFailure(this.errorMessage);

  @override
  List<Object?> get props => [errorMessage];
}

小部件:

class HomePageBuilder extends StatefulWidget {
  const HomePageBuilder({
    Key? key,
  }) : super(key: key);

  @override
  State<HomePageBuilder> createState() => _HomePageBuilderState();
}

class _HomePageBuilderState extends State<HomePageBuilder> {
  XFile? _image;

  @override
  Widget build(BuildContext context) {
    ImagePickerCubit cubit =
        ImagePickerCubit(RepositoryProvider.of<ImagePickerRepository>(context));

    return Column(
      children: <Widget>[
        Expanded(
          child: CircleAvatar(
            radius: 75,
              child: BlocBuilder<ImagePickerCubit, ImagePickerState>( //PROBLEM IS HERE
              bloc: cubit,
              builder:  (BuildContext context,ImagePickerState state) {
                if(state is ImagePickerInitialize){
                  return Container(
                    decoration: BoxDecoration(
                        color: Colors.grey[200],
                        borderRadius: BorderRadius.circular(70)),
                    width: 135,
                    height: 135,
                    child: Icon(
                      Icons.camera_alt,
                      color: Colors.grey[800],
                    ),
                  );
                }
                if(state is ImagePickerSuccess){
                    _image = state.image;
                  return ClipRRect(
                    borderRadius: BorderRadius.circular(70),
                    child: Image.file(
                      File(_image!.path),
                    ),
                  );
                }
                if(state is ImagePickerFailure){
                  return Text(state.errorMessage);
                }
                return const SizedBox();
              },
            ),
          ),
        ),
        Column(
          mainAxisAlignment: MainAxisAlignment.end,
          children: <Widget>[
            ListTile(
              leading: const Icon(Icons.photo_library),
              title: const Text('Pick photo from gallery'),
              onTap: () {
                Navigator.pop(context);
                cubit.takePhotoFromGallery();
              },
            ),
            ListTile(
              leading: const Icon(Icons.photo_camera),
              title: const Text('Take photo from camera'),
              onTap: () {
                Navigator.pop(context);
                cubit.takePhotoFromCamera();
              },
            ),
          ],
        ),
      ],
    );
  }
}

在此先感谢您的帮助!

Answer 1

只需将通用参数添加到您的 Cubit 中，例如:

class ImagePickerCubit extends Cubit<ImagePickerState> {
...