pillow + argparse example

puzzle.py

#!/usr/bin/env python3
import random
from PIL import Image


def main(source, target, cols, rows):
    im = Image.open(source)
    print("Original image size: {}x{}".format(*im.size))

    w, h = im.size

    # If the image size does not divide by (COLS, ROWS), resize it a bit.
    # This leaves us with integers and not subpixels...
    if w % cols or h % rows:
        w, h = w // cols * cols, h // rows * rows
        print("Resizing to {}x{}".format(w, h))
        im.resize((w, h))

    # piece sizes
    dx, dy = w // cols, h // rows

    def pos(x, y):
        """Returns (x0, y0, x1, y1) of a piece (x, y)"""
        x0 = x * dx
        y0 = y * dy
        return x0, y0, x0 + dx, y0 + dy

    target_image = Image.new(im.mode, (w, h))

    pieces = [(x, y) for y in range(rows) for x in range(cols)]
    random.shuffle(pieces)

    for i, piece in enumerate(pieces):
        y, x = divmod(i, cols)  # same as y, x = i // COLS, i % COLS
        # print(pos(x, y), pos(*piece))
        target_image.paste(im.crop(pos(x, y)), pos(*piece))

    target_image.save(target)
    print("Saving to", target)


if __name__ == "__main__":
    import argparse

    parser = argparse.ArgumentParser(description='Create a puzzle.')
    parser.add_argument('source', type=str, help="source file")
    parser.add_argument('target', type=str, help="target file")
    parser.add_argument('--cols', type=int, default=10,
                        help="number of columns")
    parser.add_argument('--rows', type=int, default=8, help="number of rows")

    args = parser.parse_args()
    main(args.source, args.target, args.cols, args.rows)