解析svg：路径d属性

Question

我需要解密SVG文档中的路径元素以驱动沿该路径的CNC机器。我不知道是否有解析SVG并给予某种Python的列表为d属性的任何Python库，如：

<path d="M 20 30 L 20 20 20 40 40 40"/> 

解析成

[["M", 20, 30], 
["L", 20, 20], 
["L", 20, 40], 
["L", 40, 40]] 

Answer 1

这里是一个开始它是由我和书面python 2.7.2。只要删除测试和打印报表，如果你想。

Copyright 2012 Christopher L. Ramsey 

    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. 

from collections import OrderedDict 
from re import match 
from re import split 
from re import sub 

class PathIterator(object): 
    EOI = 'End of Iteration' 
    PATH_IDENTIFIERS = r'[MLHVCSQTAmlhvcsqa]' 
    NUMBERS = r'[0-9.-^A-z]' 
    SEPERATORS = r'\s|\,' 
    PATH_END = r'[Zz]' 

    def __init__(self, path): 
     self.parseable = path.translate(None, '\t\f') 
     self.parseable = self.parseable.replace('\n', ' ') 
     print 'strip_newlines: {}'.format(self.parseable) 
     self.parseable = sub(r'([A-Za-z])([0-9]|\-)', self.insert, self.parseable) 
     print 'add_space: {}'.format(self.parseable) 
     self.parseable = self.parseable.replace(',', ' ') 
     print 'replace_commas: {}'.format(self.parseable) 
     self.parseable = sub(r'\s+', ' ', self.parseable) # replace any double space with a single space 
     print 'strip_extra_space: {}'.format(self.parseable) 
     self.tokens = split(' ', self.parseable) 
     self.map = self.produce_map(self.tokens) 
     print self.map 
     self.elements = self.process(self.map) 

    def produce_map(self, tkns): 
     self.m = OrderedDict() 
     self.i = 0 
     while self.i < len(tkns): 
      if match(self.PATH_IDENTIFIERS, tkns[self.i]): 
       self.m[self.i] = tkns[self.i] 
      elif match(self.PATH_END, tkns[self.i]): 
       self.m[self.i] = tkns[self.i] 
      else: 
       pass 
      self.i += 1 
     return self.m.items() 

    def process(self, map): 
     self.mm = [] 
     self.l = len(map) 
     for e in range(self.l): 
      try: 
       self.element = map[e] 
       self.future = map[e + 1] 
       self.ident = self.element[1] 
       self.start = self.element[0] + 1 
       self.end = self.future[0] 
       self.nbrs = self.tokens[self.start:self.end] 
      except: 
       self.element = map[e] 
       self.ident = self.element[1] 
       self.start = self.element[0] + 1 
       self.end = len(self.tokens) 
       self.nbrs = self.tokens[self.start:self.end] 
       print 'start: {} end {}'.format(self.start, self.end) 
      finally: 
       self.numbers = [] 
       for number in self.nbrs: 
        self.numbers.append(float(number)) 
       self.mm.append((self.ident, self.numbers)) 
     return iter(self.mm) 

    def next(self): 
     try: 
      return self.elements.next() 
     except: 
      return self.EOI 

    def insert(self, match_obj): 
     self.group = match_obj.group() 
     return '{} {}'.format(self.group[0], self.group[1]) 

if __name__ == '__main__': 
    inkscape_path = "M 12,90 C 8.676,90 6,87.324 6,84 L 6,82 6,14 6,12 c 0,-0.334721 0.04135,-0.6507 0.09375,-0.96875 0.0487,-0.295596 0.09704,-0.596915 0.1875,-0.875 C 6.29113,10.12587 6.302142,10.09265 6.3125,10.0625 6.411365,9.774729 6.5473802,9.515048 6.6875,9.25 6.8320918,8.976493 7.0031161,8.714385 7.1875,8.46875 7.3718839,8.223115 7.5612765,7.995278 7.78125,7.78125 8.221197,7.353194 8.72416,6.966724 9.28125,6.6875 9.559795,6.547888 9.8547231,6.440553 10.15625,6.34375 9.9000482,6.443972 9.6695391,6.580022 9.4375,6.71875 c -0.00741,0.0044 -0.023866,-0.0045 -0.03125,0 -0.031933,0.0193 -0.062293,0.04251 -0.09375,0.0625 -0.120395,0.0767 -0.2310226,0.163513 -0.34375,0.25 -0.1061728,0.0808 -0.2132809,0.161112 -0.3125,0.25 C 8.4783201,7.442683 8.3087904,7.626638 8.15625,7.8125 8.0486711,7.942755 7.9378561,8.077785 7.84375,8.21875 7.818661,8.25713 7.805304,8.30462 7.78125,8.34375 7.716487,8.446782 7.6510225,8.548267 7.59375,8.65625 7.4927417,8.850956 7.3880752,9.071951 7.3125,9.28125 7.30454,9.30306 7.288911,9.3218 7.28125,9.34375 7.2494249,9.4357 7.2454455,9.530581 7.21875,9.625 7.1884177,9.731618 7.1483606,9.828031 7.125,9.9375 7.0521214,10.279012 7,10.635705 7,11 l 0,2 0,68 0,2 c 0,2.781848 2.2181517,5 5,5 l 2,0 68,0 2,0 c 2.781848,0 5,-2.218152 5,-5 l 0,-2 0,-68 0,-2 C 89,10.635705 88.94788,10.279012 88.875,9.9375 88.83085,9.730607 88.78662,9.539842 88.71875,9.34375 88.71105,9.3218 88.69545,9.30306 88.6875,9.28125 88.62476,9.107511 88.549117,8.913801 88.46875,8.75 88.42717,8.6672 88.38971,8.580046 88.34375,8.5 88.28915,8.40279 88.216976,8.31165 88.15625,8.21875 88.06214,8.077785 87.951329,7.942755 87.84375,7.8125 87.700576,7.63805 87.540609,7.465502 87.375,7.3125 87.36383,7.3023 87.35502,7.29135 87.34375,7.28125 87.205364,7.155694 87.058659,7.046814 86.90625,6.9375 86.803679,6.86435 86.701932,6.784136 86.59375,6.71875 c -0.0074,-0.0045 -0.02384,0.0044 -0.03125,0 -0.232039,-0.138728 -0.462548,-0.274778 -0.71875,-0.375 0.301527,0.0968 0.596455,0.204138 0.875,0.34375 0.55709,0.279224 1.060053,0.665694 1.5,1.09375 0.219973,0.214028 0.409366,0.441865 0.59375,0.6875 0.184384,0.245635 0.355408,0.507743 0.5,0.78125 0.14012,0.265048 0.276135,0.524729 0.375,0.8125 0.01041,0.03078 0.02133,0.06274 0.03125,0.09375 0.09046,0.278085 0.1388,0.579404 0.1875,0.875 C 89.95865,11.3493 90,11.665279 90,12 l 0,2 0,68 0,2 c 0,3.324 -2.676,6 -6,6 l -72,0 z" 
    mdn_path = "M10 80 Q 52.5 10, 95 80 T 180 80" 
    w3c_path = "M100,200 C100,100 250,100 250,200 S400,300 400,200" 
    w3c_path_neg = "M-100,200 C100,100 250,100 250,200 S-400,300 400,200" 
    w3c_path_nl = ''' 
      M600,350 l 50,-25 
      a25,25 -30 0,1 50,-25 l 50,-25 
      a25,50 -30 0,1 50,-25 l 50,-25 
      a25,75 -30 0,1 50,-25 l 50,-25 
      a25,100 -30 0,1 50,-25 l 50,-25 
      ''' 
    paths = [inkscape_path, mdn_path, w3c_path, str.strip(w3c_path_nl), w3c_path_neg] 
    for path in paths: 
     p = PathIterator(path) 
     char = '' 
     while char != PathIterator.EOI: 
      char = p.next() 
      print char 

Answer 2

获取d-string可以是倒在使用svgpathtools几行，其余的可以使用正则表达式来完成。

from svgpathtools import svg2paths 
paths, attributes = svg2paths('some_svg_file.svg') 

路径是svgpathtools路径对象（只包含曲线信息，没有颜色，款式等）的列表。 属性是属性的字典对象列表。

假设您有兴趣的路径是第一（第0）在你的SVG上市，那么只提取d串您可以使用：

d = attributes[0]['d'] # d-string from first path in SVG 

# Now for some regular expressions magic 
import re 
split_by_letters = re.findall('[A-Z|a-z][^A-Z|a-z]*', d) 
split_as_you_want = [] 
for x in split_by_letters: 
    nums = x[1:].replace(',',' ').split() # list of numbers after letter 
    for k in range(len(nums) // 2): 
     split_as_you_want.append([x[0]] + [nums[k]] + [nums[k+1]]) 
print split_as_you_want 

我没有转换数字转换为字符串，因为你想怎么做取决于它们是否总是整数，以及你是否在乎它们保持那种方式。对于大多数目的来说，这可以通过类似于下面的“nums = ...”行来完成。

for k, n in enumerate(nums): 
    try: 
     nums[k] = int(n) 
    except ValueError: 
     nums[k] = float(n)