Create CSS spritesheet with mogrify and glue-sprite

black_white_css_sprites.py

import os
import sys
import atexit
import shutil
import subprocess

def main(width, height):
    # get image paths in full
    dir_path = os.path.dirname(os.path.realpath(__file__))
    dir_images = os.path.join(dir_path, 'sprite-src/')
    image_filenames = os.listdir(dir_images)
    image_fullpaths = [os.path.join(dir_images, i) for i in image_filenames]
    build_destination = os.path.join(dir_path, 'src/assets/')

    # create and aggregate black and white versions
    bw_names = []
    bw_paths = []
    for name, path in zip(image_filenames, image_fullpaths):
        splits = name.split('.') 
        bw_name = ''.join([splits[0], '_bw', '.', splits[1]])
        bw_path = os.path.join(dir_images, bw_name)
        subprocess.call(['convert', path, '-colorspace', 'Gray', bw_path])
        bw_names.append(bw_name)
        bw_paths.append(bw_path)

    # register function to remove black and white images when script exists
    def remove_bw_images():
        for path in bw_paths:
            os.remove(path)

    atexit.register(remove_bw_images)

    # create a temp folder with centered images with same transparent padding
    # also delete it at end of execution
    tmp_mogrified = '/tmp/sprites-mogrified'

    def remove_mogrified_images():
        try:
            shutil.rmtree(tmp_mogrified)
        except Exception:
            pass

    remove_mogrified_images()
    os.mkdir(tmp_mogrified)
    # atexit.register(remove_mogrified_images)

    # mogrify images to same size and with transparency
    # https://stackoverflow.com/questions/32466048/imagemagick-convert-crop-and-resize
    size_string = ''.join([str(width), 'x', str(height)])
    subprocess.call(['mogrify', 
        '-resize', size_string, 
        '-extent', size_string, 
        '-background', 'transparent',
        '-gravity', 'center', 
        '-format', 'png', 
        '-path', tmp_mogrified,
        ''.join([dir_images, '/', '*.png'])
    ])

    # create sprite image and unedited css file
    subprocess.call(['glue-sprite', tmp_mogrified, build_destination])


if __name__ == "__main__":
    w = int(sys.argv[1])
    h = int(sys.argv[2])
    main(w, h)