demo.py

import logging
import argparse
import re
from PIL import Image, ImageDraw
import polyskel

if __name__ == "__main__":
    logging.basicConfig()

    argparser = argparse.ArgumentParser(description="Construct the straight skeleton of a polygon. The polygon is to be given as a counter-clockwise series of vertices specified by their coordinates: see the example files for the exact format.")
    argparser.add_argument('polygon_file', metavar="<polygon-file>", type=argparse.FileType('r'), help="text file describing the polygon ('-' for standard input)")
    argparser.add_argument('--verbose', '--v', action="store_true", default=False, help="Show construction of the skeleton")
    argparser.add_argument('--log', dest="loglevel", choices=['DEBUG', 'INFO', 'WARNING', 'ERROR'], default='WARNING', help="Set log level")
    args = argparser.parse_args()

    polyskel.log.setLevel(getattr(logging, args.loglevel))
    polygon_line_pat = re.compile(r"\s*(?P<coord_x>\d+(\.\d+)?)\s*,\s*(?P<coord_y>\d+(\.\d+)?)\s*(#.*)?")

    contours = []
    poly = []
    for line in args.polygon_file:
        line = line.strip()
        if not line or line.startswith('#'):
            continue

        if line.startswith('-'):
            contours.append(poly)
            poly = []
            continue

        match = polygon_line_pat.match(line)
        poly.append((float(match.group("coord_x")), float(match.group("coord_y"))))

    if not args.polygon_file.isatty():
        args.polygon_file.close()

    contours.append(poly)
    poly = contours[0]
    holes = contours[1:] if len(contours) > 0 else None
    bbox_end_x = int(max(poly, key=lambda x: x[0])[0]+20)
    bbox_end_y = int(max(poly, key=lambda x: x[1])[1]+20)

    im = Image.new("RGB", (bbox_end_x, bbox_end_y), "white");
    draw = ImageDraw.Draw(im);
    if args.verbose:
        polyskel.set_debug((im, draw))


    for contour in contours:
        for point, next in zip(contour, contour[1:]+contour[:1]):
            draw.line((point[0], point[1], next[0], next[1]), fill=0)
    print(poly)
    print(holes)
    skeleton = polyskel.skeletonize(poly, holes)

    for res in skeleton:
        print(res)

    for arc in skeleton:
        for sink in arc.sinks:
            draw.line((arc.source.x, arc.source.y, sink.x, sink.y), fill="red")
    im.show();