ImgCrop(...),  //  ImageProvider
  ImgCrop.file(...) // Image file
  ImgCrop.asset(...) // Image assets your local

final imgCropKey = GlobalKey<ImgCropState>();

Widget _buildCropImage() {
  return Container(
      color: Colors.black,
      child: ImgCrop(
        key: cropKey,
        chipRadius: 150,  // crop area radius
        chipShape: ChipShape.rect,
        chipRatio: 2 / 1,
        image: FileImage(imageFile), // you selected image file
      ),
  );
}

  final croppedFile = await crop.cropCompleted(
    croppedImage,
    {pictureQuality: 900}
  )

floatingActionButton: FloatingActionButton(
  onPressed: () async {
    final crop = cropKey.currentState;
    final croppedFile =
        await crop.cropCompleted(args['image'], pictureQuality: 900);

    // show you croppedFile ……
    showImage(context, croppedFile);
  },