slides.py

import base64
import json
import os
import cv2
import numpy
import re

import numpy as np
from PIL import Image
from abc import ABCMeta, abstractmethod


def numerical_sort(value):
    numbers = re.compile(r'(\d+)')
    parts = numbers.split(value)
    parts[1::2] = map(int, parts[1::2])
    return parts


class Slide(object):
    """
    Represents a slide
    """

    def __init__(self, time, img):
        """
        Default initializer for a slide representation
        :param time: the time when the slide appears
        :param img: the image representing the slide
        """
        self.time = time
        self.img = img
        self.marked = False
        self.times = []
        self.reference = None
        self.page_number = 0

    def add_time(self, time):
        """
        Add an additional instance in time, when the slide
        is displayed.
        :param time: the time when the slide is displayed
        """
        self.times.append(time)

    def to_dict(self):
        """
        Convert the Slide object to a dictionary, handling image serialization.
        """
        # Convert the image to a bytes object and then encode it to a base64 string
        _, buffer = cv2.imencode('.jpg', self.img)
        img_encoded = base64.b64encode(buffer).decode('utf-8')

        return {
            'time': self.time,
            'img': img_encoded,  # Use the encoded image string
            'marked': self.marked,
            'times': self.times,
            'reference': self.reference,
            'page_number': self.page_number
        }

    @classmethod
    def from_dict(cls, data):
        """
        Create a Slide object from a dictionary, handling image deserialization.
        """
        # Decode the image from a base64 string to a bytes object and then to a numpy array
        img_decoded = base64.b64decode(data['img'])
        img = cv2.imdecode(np.frombuffer(img_decoded, np.uint8), cv2.IMREAD_COLOR)

        slide = cls(data['time'], img)
        slide.marked = data.get('marked', False)
        slide.times = data.get('times', [])
        slide.reference = data.get('reference')
        slide.page_number = data.get('page_number', 0)
        return slide

    def to_json(self):
        """
        Convert the Slide object to a JSON string.
        """
        return json.dumps(self.to_dict())

    @classmethod
    def from_json(cls, json_str):
        """
        Create a Slide object from a JSON string.
        """
        data = json.loads(json_str)
        return cls.from_dict(data)


def slides_to_json(slides):
    """
    Convert a list of Slide objects to a JSON string.
    """
    return json.dumps([slide.to_dict() for slide in slides])


def slides_from_json(json_str):
    """
    Create a list of Slide objects from a JSON string.
    """
    slides_data = json.loads(json_str)
    return [Slide.from_dict(slide_data) for slide_data in slides_data]


class SlideDataHelper(object):
    """
    The helps to get slides from data.
    """

    def __init__(self, path, image_type="opencv"):
        """
        Default initializer
        :param path: the path, where the slide is stored on disk
        :image_type: the type representing the image. Either "opencv" or "pil" might be required for certain usage.
        """
        self.path = path
        if image_type == "pil":
            self.imgreader = PILReader()
        else:
            self.imgreader = OpenCVReader()

    def get_slides(self):
        """
        Gets the slide from disk and returns them as list of "Slide"
        objects.
        :return: The slides stored on disk as list of "Slide" objects.
        """
        slides = []
        for filename in sorted(os.listdir(self.path), key=numerical_sort):
            file_path = os.path.join(self.path, filename)
            _, ext = os.path.splitext(file_path)
            if not is_image(ext):
                continue
            time, _ = os.path.splitext(filename)
            slide = Slide(time, self.imgreader.get_img(file_path))
            slides.append(slide)

        return slides


class ImageReader(object):
    __metaclass__ = ABCMeta

    @abstractmethod
    def get_img(self, file_path):
        pass


class PILReader(ImageReader):
    def get_img(self, file_path):
        return Image.open(file_path)


class OpenCVReader(ImageReader):
    def get_img(self, file_path):
        return cv2.imread(file_path)


def convert_to_opencv(img):
    return cv2.cvtColor(numpy.array(img.convert('RGB')), cv2.COLOR_RGB2BGR)


def convert_to_PIL(img):
    return Image.fromarray(img)


def is_image(ext):
    """
    Checks if the file_format is a supported image to read.
    :param ext: the extension of a file.
    :return: whether or not the file is a image
    """
    return ext == '.jpeg' or ext == '.png' or ext == '.jpg' or ext == '.bmp'