svgutil.py

#!/usr/bin/python3
# -*- coding: utf-8 -*-
#
# Copyright 2016 Unicode Inc. All rights reserved.
#
# Licensed under the Apache License, Version 2.0 (the "License");
# you may not use this file except in compliance with the License.
# You may obtain a copy of the License at
#
#      http://www.apache.org/licenses/LICENSE-2.0
#
# Unless required by applicable law or agreed to in writing, software
# distributed under the License is distributed on an "AS IS" BASIS,
# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
# See the License for the specific language governing permissions and
# limitations under the License.
#
import itertools


def is_similar(a, b, maxDelta):
    if (a is not b) and (a is None or b is None):
        return False
    if a.tag != b.tag:
        return False
    for name, valueA in a.attrib.items():
        valueB = b.attrib.get(name)
        if name in ("d", "viewBox", "x", "y"):
            if not is_similar_path(valueA, valueB, maxDelta):
                return False
        else:
            if valueA != valueB:
                return False
    for childA, childB in itertools.zip_longest(a, b):
        if not is_similar(childA, childB, maxDelta):
            return False
    return True


def is_similar_path(a, b, maxDelta):
    for itemA, itemB in itertools.zip_longest(simplified_path(a), simplified_path(b)):
        if itemA is None or itemB is None:
            return False
        try:
            if abs(float(itemA) - float(itemB)) > maxDelta:
                return False
        except ValueError:
            if itemA != itemB:
                return False
    return True


# http://codereview.stackexchange.com/a/88051
def parse_path(path_data):
    digit_exp = "0123456789eE"
    comma_wsp = ", \t\n\r\f\v"
    drawto_command = "MmZzLlHhVvCcSsQqTtAa"
    sign = "+-"
    exponent = "eE"
    float = False
    entity = ""
    for char in path_data:
        if char in digit_exp:
            entity += char
        elif char in comma_wsp and entity:
            yield entity
            float = False
            entity = ""
        elif char in drawto_command:
            if entity:
                yield entity
                float = False
                entity = ""
            yield char
        elif char == ".":
            if float:
                yield entity
                entity = "."
            else:
                entity += "."
                float = True
        elif char in sign:
            if entity and entity[-1] not in exponent:
                yield entity
                float = False
                entity = char
            else:
                entity += char
    if entity:
        yield entity


# Iterate path entities, removing subpaths consisting of only "moveto" commands.
class simplified_path:
    def __init__(self, path_data):
        self.path = parse_path(path_data)
        self.subpath = []

    def __iter__(self):
        return self

    def __next__(self):
        # Exhaust the current subpath before proceeding.
        if len(self.subpath):
            return self.subpath.pop(0)

        # Buffer the current subpath.
        for entity in self.path:
            self.subpath.append(entity)
            if entity in "Zz":
                only_moves = True
                for subentity in iter(self.subpath):
                    if subentity in "MmZz":
                        pass
                    elif subentity in "LlHhVvCcSsQqTtAa":
                        only_moves = False
                        break
                if only_moves:
                    self.subpath = []
                else:
                    break

        if len(self.subpath):
            return self.subpath.pop(0)
        else:
            raise StopIteration