Creates grid from SVG. Note that full image can be recovered from any piece, because any piece contain the full image just with modified boundaries.

gridify-svg.py

#!/usr/bin/env python3

import argparse
import xml.etree.ElementTree
import re
import os
from collections import namedtuple
from decimal import Decimal
from fractions import Fraction

SIZE_REGEX = re.compile("^([0-9.]+)([a-z]*)$")
VIEWBOX_REGEX = re.compile("[ ,]+")

class Size(namedtuple('Size', ['number', 'unit'])):
	@staticmethod
	def parse(size):
		items = SIZE_REGEX.fullmatch(size)
		return Size(
			Fraction(Decimal(items.group(1))),
			items.group(2)
		)
	@staticmethod
	def parse_number(number):
		return Size(Fraction(Decimal(number)), "")
	
	def __truediv__(self, divisor):
		return Size(self.number / divisor, self.unit)

	def __rmul__(self, multiplicator):
		return self*multiplicator

	def __mul__(self, multiplicator):
		return Size(self.number * multiplicator, self.unit)
		
	def __add__(self, summand):
		if isinstance(summand, Size):
			if self.unit != summand.unit:
				raise Error("Cannot add apples to oranges!")
			return self + summand.number
		return Size(self.number+summand, self.unit)

	def __radd(self, summand):
		return self+summand
	
	def to_svg_string(self):
		return str(float(self.number))+self.unit

DEFAULT_OUTPUT_FILENAMES="{input_basename}-{y}-{x}.svg"

parser = argparse.ArgumentParser(description='Divides an SVG image to pieces of a grid. A bit dirty script focused primarily on SVGs from Inkscape.')
parser.add_argument('file', type=str, help='input file')
parser.add_argument('--vertical-parts', type=int, help='Number of vertical parts.', default=1)
parser.add_argument('--horizontal-parts', type=int, help='Number of horizontal parts.', default=1)
parser.add_argument('--output-filenames', type=str, help='Format string for output file names. By default, it is '+DEFAULT_OUTPUT_FILENAMES, default=DEFAULT_OUTPUT_FILENAMES)
args = parser.parse_args()

input_file=args.file
vertical_parts=args.vertical_parts
horizontal_parts=args.horizontal_parts
output_filenames=args.output_filenames
input_basename=os.path.splitext(input_file)[0]

tree = xml.etree.ElementTree.parse(input_file)
svg_root = tree.getroot()

# parse and calculate canvas size
canvas_base_height=Size.parse(svg_root.attrib["height"])
canvas_base_width=Size.parse(svg_root.attrib["width"])
canvas_part_height=canvas_base_height/vertical_parts
canvas_part_width=canvas_base_width/horizontal_parts

# parse and calculate viewBox
[base_offset_x, base_offset_y, base_width, base_height] = list(map(Size.parse_number, VIEWBOX_REGEX.split(svg_root.attrib["viewBox"])))
part_height=base_height/vertical_parts
part_width=base_width/horizontal_parts

# adjust canvas size
svg_root.set("width", canvas_part_width.to_svg_string())
svg_root.set("height", canvas_part_height.to_svg_string())

for x in range(horizontal_parts):
	x_offset=base_offset_x+x*part_width
	for y in range(vertical_parts):
		y_offset=part_height*y
		svg_root.set("viewBox", " ".join(map(lambda x: x.to_svg_string(), [x_offset, y_offset, part_width, part_height])))
		tree.write(output_filenames.format(x=x, y=y, input_file=input_file, input_basename=input_basename), "utf-8")