Gerber file pad shrinker

shrink_apertures.py

#!/usr/bin/python

import sys
import re

subtract = float(sys.argv[1]) / 1000
mode = 'IN'

with open(sys.argv[2], "r") as f:

	for line in f:

		mode_match = re.match(r'%MO(?P<mode>IN|MM)*%', line)
		match = re.match(r'^%ADD(?P<aperture_num>[0-9]{2,})(?P<shape>[CROP]),(?P<tail>.*)\*%', line)

		if mode_match:
			new_mode = mode_match.group('mode')

			if mode == 'IN':
				if new_mode == 'MM':
					subtract *= 25.4

			elif mode == 'MM':
				if new_mode == 'IN':
					subtract /= 25.4


			sys.stdout.write(line)

		elif match:

			shape = match.group('shape')
			tail = match.group('tail')
			aperture_num = match.group('aperture_num')

			dimensions = re.findall(r'[0-9]*\.?[0-9]+', tail)

			shrink = []
			grow = []
			keep = []

			if shape == 'C':
				shrink = dimensions[:1]

				grow = dimensions[1:]

			elif shape == 'R':
				shrink = dimensions[:2]

				grow = dimensions[2:]


			elif shape == 'O':
				shrink = dimensions[:2]

				grow = dimensions[2:]
				

			elif shape == 'P':
				shrink = dimensions[:1]

				keep = dimensions[1:3]

				if len(dimensions) > 3:
					grow = dimensions[3:]

			else:
				sys.stderr.write("Unknown aperture type: " + line)
				sys.stdout.write(line)

				continue

			out = []
			out.extend(map(lambda e: "{:.4f}".format(float(e) - subtract).rstrip('0').rstrip('.'), shrink))
			out.extend(keep)
			out.extend(map(lambda e: "{:.4f}".format(float(e) + subtract).rstrip('0').rstrip('.'), grow))


			sys.stdout.write("%ADD{}{},{}*%\n".format(aperture_num, shape, "X".join(out)))

		else:
			sys.stdout.write(line)