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1def _prefer_non_zero(*args):
2    for arg in args:
3        if arg != 0:
4            return arg
5    return 0.
6
7
8def _ntos(n):
9    # %f likes to add unnecessary 0's, %g isn't consistent about # decimals
10    return ('%.3f' % n).rstrip('0').rstrip('.')
11
12
13def _strip_xml_ns(tag):
14    # ElementTree API doesn't provide a way to ignore XML namespaces in tags
15    # so we here strip them ourselves: cf. https://bugs.python.org/issue18304
16    return tag.split('}', 1)[1] if '}' in tag else tag
17
18
19class PathBuilder(object):
20    def __init__(self):
21        self.paths = []
22
23    def _start_path(self, initial_path=''):
24        self.paths.append(initial_path)
25
26    def _end_path(self):
27        self._add('z')
28
29    def _add(self, path_snippet):
30        path = self.paths[-1]
31        if path:
32            path += ' ' + path_snippet
33        else:
34            path = path_snippet
35        self.paths[-1] = path
36
37    def _move(self, c, x, y):
38        self._add('%s%s,%s' % (c, _ntos(x), _ntos(y)))
39
40    def M(self, x, y):
41        self._move('M', x, y)
42
43    def m(self, x, y):
44        self._move('m', x, y)
45
46    def _arc(self, c, rx, ry, x, y, large_arc):
47        self._add('%s%s,%s 0 %d 1 %s,%s' % (c, _ntos(rx), _ntos(ry), large_arc,
48                                            _ntos(x), _ntos(y)))
49
50    def A(self, rx, ry, x, y, large_arc=0):
51        self._arc('A', rx, ry, x, y, large_arc)
52
53    def a(self, rx, ry, x, y, large_arc=0):
54        self._arc('a', rx, ry, x, y, large_arc)
55
56    def _vhline(self, c, x):
57        self._add('%s%s' % (c, _ntos(x)))
58
59    def H(self, x):
60        self._vhline('H', x)
61
62    def h(self, x):
63        self._vhline('h', x)
64
65    def V(self, y):
66        self._vhline('V', y)
67
68    def v(self, y):
69        self._vhline('v', y)
70
71    def _parse_rect(self, rect):
72        x = float(rect.attrib.get('x', 0))
73        y = float(rect.attrib.get('y', 0))
74        w = float(rect.attrib.get('width'))
75        h = float(rect.attrib.get('height'))
76        rx = float(rect.attrib.get('rx', 0))
77        ry = float(rect.attrib.get('ry', 0))
78
79        rx = _prefer_non_zero(rx, ry)
80        ry = _prefer_non_zero(ry, rx)
81        # TODO there are more rules for adjusting rx, ry
82
83        self._start_path()
84        self.M(x + rx, y)
85        self.H(x + w - rx)
86        if rx > 0:
87            self.A(rx, ry, x + w, y + ry)
88        self.V(y + h - ry)
89        if rx > 0:
90            self.A(rx, ry, x + w - rx, y + h)
91        self.H(x + rx)
92        if rx > 0:
93            self.A(rx, ry, x, y + h - ry)
94        self.V(y + ry)
95        if rx > 0:
96            self.A(rx, ry, x + rx, y)
97        self._end_path()
98
99    def _parse_path(self, path):
100        if 'd' in path.attrib:
101            self._start_path(initial_path=path.attrib['d'])
102
103    def _parse_polygon(self, poly):
104        if 'points' in poly.attrib:
105            self._start_path('M' + poly.attrib['points'])
106            self._end_path()
107
108    def _parse_circle(self, circle):
109        cx = float(circle.attrib.get('cx', 0))
110        cy = float(circle.attrib.get('cy', 0))
111        r = float(circle.attrib.get('r'))
112
113        # arc doesn't seem to like being a complete shape, draw two halves
114        self._start_path()
115        self.M(cx - r, cy)
116        self.A(r, r, cx + r, cy, large_arc=1)
117        self.A(r, r, cx - r, cy, large_arc=1)
118
119    def add_path_from_element(self, el):
120        tag = _strip_xml_ns(el.tag)
121        parse_fn = getattr(self, '_parse_%s' % tag.lower(), None)
122        if not callable(parse_fn):
123            return False
124        parse_fn(el)
125        return True
126