NibasaViewer/viewer/utils.py

# Standard library imports.
from pathlib import Path

# External library imports.
from PIL import Image

# Django imports.
from django.conf import settings

###########################################################################################
# Constants.                                                                              #
###########################################################################################

THUMB_SIZE = (128, 128)

# Supported image extensions for fast file filtering (avoids costly MIME-type detection)
IMAGE_EXTENSIONS = {'.jpg', '.jpeg', '.png', '.gif', '.webp', '.bmp', '.tiff', '.tif', '.svg'}

###########################################################################################
# Helper functions.                                                                       #
###########################################################################################


def is_image_file(path):
    """
    Fast image detection using file extension instead of MIME-type checking.

    :param path: A pathlib.Path instance or string path to check.
    :return: True if the file extension matches a known image format.
    """
    if isinstance(path, str):
        path = Path(path)
    return path.suffix.lower() in IMAGE_EXTENSIONS


def make_thumbnail(image):
    """
    Creates a thumbnail in the corresponding THUMBNAILS_ROOT directory for the given image.

    :param image: A pathlib.Path instance pointing to a file inside the GALLERY_ROOT directory.
    """

    if image.exists():
        thumb_path = Path(str(image).replace(str(settings.GALLERY_ROOT), str(settings.THUMBNAILS_ROOT)))

        thumb_path.parent.mkdir(parents = True, exist_ok = True)

        if not thumb_path.exists():
            try:
                with Image.open(str(image)) as pilimg:
                    pilimg.thumbnail(THUMB_SIZE)
                    pilimg.save(str(thumb_path))
            except Exception:
                pass