Spritesheet image cutter

spritesheet_cutter.py

#!/usr/bin/env python
#-*- coding: utf-8 -*-
#-----------------------------------------------------------------------
# Author: delimitry
#-----------------------------------------------------------------------

import os
import sys
from PIL import Image
from argparse import ArgumentParser


def find_horizontal_borders(image, border_color):
    """
    Find horizontal border lines with defined color
    """
    w, h = image.size
    pixels = image.load()
    horizontals = []
    for j in xrange(h):
        for i in xrange(w):
            if pixels[i, j] != border_color:
                break
        else:
            horizontals.append(j)
    return horizontals


def find_vertial_borders(image, border_color):
    """
    Find vertical border lines with defined color
    """
    w, h = image.size
    pixels = image.load()
    verticals = []
    for i in xrange(w):
        for j in xrange(h):
            if pixels[i, j] != border_color:
                break
        else:
            verticals.append(i)
    return verticals


def find_areas(image, border_color):
    """
    Find sprite areas and return a list of rectangles (x, y, w, h).
    """
    w, h = image.size
    horizontals = find_horizontal_borders(image, border_color)
    areas = []
    prev_horizontal = 0
    for h in horizontals:
        if h - prev_horizontal > 1:
            verticals = find_vertial_borders(
                image.crop((0, prev_horizontal + 1, w, prev_horizontal + (h - prev_horizontal))), border_color)
            prev_vertical = 0
            for v in verticals:
                if v - prev_vertical > 1:
                    areas.append(
                        (prev_vertical + 1, prev_horizontal + 1, v - prev_vertical - 1, h - prev_horizontal - 1))
                prev_vertical = v
        prev_horizontal = h
    return areas


def str_to_color(value):
    """
    Convert str value to color (tuple of ints)
    """
    try:
        if ',' not in value or value.count(',') not in (2, 3):
            raise
        color = tuple([int(x) for x in value.split(',')])
        for c in color:
            if not 0 <= c <= 255:
                raise
        return color
    except:
        raise Exception('Invalid format of color. Must be (R,G,B) or (R,G,B,A), '
                        'where RGBA channels must be in [0..255]')


def cut_and_save_sprites(image, areas, output_folder):
    """
    Cut sprites from image using found areas and save to output folder, grouping them by size
    """
    if not os.path.exists(output_folder):
        os.makedirs(output_folder)
    if not areas:
        return
    group = 0
    index = 0
    # get [w, h] from first area (x, y, w, h)
    prev_size = areas[0][2:4]
    for area in areas:
        # assume that a new group starts when a new size is found
        if area[2:4] != prev_size:
            prev_size = area[2:4]
            group += 1
            index = 0
        image.crop((area[0], area[1], area[0] + area[2] - 0, area[1] + area[3] - 0)).save(
            os.path.join(output_folder, 'group_%02d_index_%03d.png' % (group, index)))
        index += 1


def main():
    # prepare arguments parser
    parser = ArgumentParser(usage='%(prog)s [options]', description='Spritesheet image cutter')
    parser.add_argument('-i', '--input', dest='input', help='spritesheet image')
    parser.add_argument('-c', '--color', dest='color',
        help='border RGB/RGBA color (e.g.: 255,0,128 or 0,0,0,255), by default color of top left pixel', default='')
    parser.add_argument('-o', '--output', dest='output',
        help='output sprites folder, by default current folder', default='./')
    parser.add_argument('-v', '--version', action='version', version='Spritesheet image cutter v0.1')

    args = parser.parse_args()
    if not args.input:
        parser.print_help()
        sys.exit()

    image = Image.open(args.input)
    left_top_color = image.getpixel((0, 0))
    if args.color:
        try:
            border_color = str_to_color(args.color)
        except Exception as ex:
            sys.exit(ex)
    else:
        # get top left pixel color if not color passed
        border_color = left_top_color

    # check color channels
    if len(border_color) != len(left_top_color):
        print 'Warning: Image color channels number is %d, but you have passed %d.' % (
            len(left_top_color), len(border_color))
        sys.exit()

    areas = find_areas(image, border_color)
    if not areas:
        print 'No sprites were found.'
        sys.exit()
    print 'Saving %s sprites to "%s"' % (len(areas), os.path.abspath(args.output))
    cut_and_save_sprites(image, areas, args.output)


if __name__ == '__main__':
    main()