vector_layer_split.py

#!/usr/bin/env python3

"""
Application for splitting groups from one SVG file into separate files

Usage:
python3 vector_layer_split.py infile format outdir

Usage Example:
python3 vector_layer_split.py vector_source.svg tw ../src/art/vector/layers/
"""

import argparse
import copy
import os
import re

import lxml.etree as etree
import normalize_svg
import svg_split_utils

parser = argparse.ArgumentParser(
    description='Application for splitting groups from one SVG file into separate files.')
parser.add_argument('-o', '--output', dest='output_dir', required=True,
                    help='output directory')
parser.add_argument('-f', '--format', dest='output_format',
                    choices=['svg', 'tw'], default='svg', help='output format.')
parser.add_argument('-p', '--prefix', dest='prefix', default='',
                    help='Prepend this string to result file names')
parser.add_argument('input_file', metavar='FILENAME', nargs='+',
                    help='Input SVG file with layers')

args = parser.parse_args()
output_format = args.output_format
output_directory = args.output_dir


def split_file(input_file):
    tree = etree.parse(input_file)
    normalize_svg.fix(tree)

    ns = {
        'svg': 'http://www.w3.org/2000/svg',
        'inkscape': 'http://www.inkscape.org/namespaces/inkscape',
        'sodipodi': "http://sodipodi.sourceforge.net/DTD/sodipodi-0.dtd",
    }

    # strip undesired editor attributes from the tree
    etree.strip_attributes(tree, f"{{{ns['inkscape']}}}*", f"{{{ns['sodipodi']}}}*");

    # prepare output template
    template = copy.deepcopy(tree)
    root = template.getroot()

    # remove all svg root attributes except document size
    for a in root.attrib:
        if a != "viewBox":
            del root.attrib[a]

    # remove all content, including metadata
    # for twine output, style definitions are removed, too
    defs = None
    for e in root:
        if e.tag == etree.QName(ns['svg'], 'defs'):
            defs = e
        if (e.tag == etree.QName(ns['svg'], 'g') or
                e.tag == etree.QName(ns['svg'], 'metadata') or
                e.tag == etree.QName(ns['svg'], 'defs') or
                e.tag == etree.QName(ns['sodipodi'], 'namedview') or
                (output_format == 'tw' and e.tag == etree.QName(ns['svg'], 'style'))
        ):
            root.remove(e)
    # template preparation finished

    # prepare regex for later use
    regex_xmlns = re.compile(' xmlns[^ ]+')
    regex_space = re.compile(r'[>]\s+[<]')

    # find all groups
    layers = tree.xpath('//svg:g', namespaces=ns)
    for layer in layers:
        i = layer.get('id')
        if (  # disregard non-content groups
                i.endswith("_") or  # manually suppressed with underscore
                i.startswith("XMLID") or  # Illustrator generated group
                i.startswith("g")  # Inkscape generated group
        ):
            continue

        # create new canvas
        output = copy.deepcopy(template)
        # copy all shapes into template
        canvas = output.getroot()
        for e in layer:
            canvas.append(e)
        # represent template as SVG (binary string)
        svg = etree.tostring(output, pretty_print=False)
        # poor man's conditional defs insertion
        # TODO: extract only referenced defs (filters, gradients, ...)
        # TODO: detect necessity by traversing the elements. do not stupidly search in the string representation
        if "filter:" in svg.decode('utf-8'):
            # it seems there is a filter referenced in the generated SVG, re-insert defs from main document
            canvas.insert(0, defs)
            # re-generate output
            svg = etree.tostring(output, pretty_print=False)

        if output_format == 'tw':
            # remove unnecessary attributes
            # TODO: never generate unnecessary attributes in the first place
            svg = svg.decode('utf-8')
            svg = regex_xmlns.sub('', svg)
            svg = svg.replace('\n', '').replace('\r', '')  # print cannot be multi-line
            svg = regex_space.sub('><', svg)  # remove indentation
            svg = svg.replace('svg:', '')  # svg namespace was removed
            if "Boob" in i:  # internal groups are used for scaling
                svg = svg.replace('<g ', '<g data-transform="boob" ')  # boob art uses the boob scaling
            elif "Belly" in i:
                svg = svg.replace('<g ', '<g data-transform="belly" ')  # belly art uses the belly scaling
            elif "Balls" in i:
                svg = svg.replace('<g ', '<g data-transform="balls" ')  # balls art uses the balls scaling
            else:
                svg = svg.replace('<g ', '<g data-transform="art" ')  # otherwise use default scaling
        if not svg.endswith(os.linesep):
            svg += os.linesep
        svg = svg.encode('utf-8')

        # save SVG string to file
        svg_split_utils.save(layer, args.prefix, output_directory, output_format, svg)


if not os.path.exists(output_directory):
    os.makedirs(output_directory)

for f in args.input_file:
    split_file(f)