197 lines
7.0 KiB
Python
197 lines
7.0 KiB
Python
"""This submodule contains the path_parse() function used to convert SVG path
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element d-strings into svgpathtools Path objects.
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Note: This file was taken (nearly) as is from the svg.path module
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(v 2.0)."""
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# External dependencies
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from __future__ import division, absolute_import, print_function
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import re
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# Internal dependencies
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from .path import Path, Line, QuadraticBezier, CubicBezier, Arc
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COMMANDS = set('MmZzLlHhVvCcSsQqTtAa')
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UPPERCASE = set('MZLHVCSQTA')
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COMMAND_RE = re.compile("([MmZzLlHhVvCcSsQqTtAa])")
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FLOAT_RE = re.compile("[-+]?[0-9]*\.?[0-9]+(?:[eE][-+]?[0-9]+)?")
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def _tokenize_path(pathdef):
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for x in COMMAND_RE.split(pathdef):
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if x in COMMANDS:
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yield x
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for token in FLOAT_RE.findall(x):
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yield token
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def parse_path(pathdef, current_pos=0j):
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# In the SVG specs, initial movetos are absolute, even if
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# specified as 'm'. This is the default behavior here as well.
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# But if you pass in a current_pos variable, the initial moveto
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# will be relative to that current_pos. This is useful.
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elements = list(_tokenize_path(pathdef))
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# Reverse for easy use of .pop()
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elements.reverse()
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segments = Path()
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start_pos = None
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command = None
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while elements:
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if elements[-1] in COMMANDS:
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# New command.
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last_command = command # Used by S and T
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command = elements.pop()
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absolute = command in UPPERCASE
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command = command.upper()
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else:
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# If this element starts with numbers, it is an implicit command
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# and we don't change the command. Check that it's allowed:
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if command is None:
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raise ValueError("Unallowed implicit command in %s, position %s" % (
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pathdef, len(pathdef.split()) - len(elements)))
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if command == 'M':
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# Moveto command.
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x = elements.pop()
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y = elements.pop()
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pos = float(x) + float(y) * 1j
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if absolute:
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current_pos = pos
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else:
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current_pos += pos
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# when M is called, reset start_pos
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# This behavior of Z is defined in svg spec:
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# http://www.w3.org/TR/SVG/paths.html#PathDataClosePathCommand
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start_pos = current_pos
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# Implicit moveto commands are treated as lineto commands.
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# So we set command to lineto here, in case there are
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# further implicit commands after this moveto.
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command = 'L'
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elif command == 'Z':
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# Close path
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if not (current_pos == start_pos):
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segments.append(Line(current_pos, start_pos))
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segments.closed = True
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current_pos = start_pos
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start_pos = None
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command = None # You can't have implicit commands after closing.
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elif command == 'L':
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x = elements.pop()
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y = elements.pop()
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pos = float(x) + float(y) * 1j
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if not absolute:
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pos += current_pos
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segments.append(Line(current_pos, pos))
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current_pos = pos
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elif command == 'H':
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x = elements.pop()
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pos = float(x) + current_pos.imag * 1j
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if not absolute:
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pos += current_pos.real
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segments.append(Line(current_pos, pos))
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current_pos = pos
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elif command == 'V':
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y = elements.pop()
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pos = current_pos.real + float(y) * 1j
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if not absolute:
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pos += current_pos.imag * 1j
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segments.append(Line(current_pos, pos))
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current_pos = pos
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elif command == 'C':
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control1 = float(elements.pop()) + float(elements.pop()) * 1j
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control2 = float(elements.pop()) + float(elements.pop()) * 1j
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end = float(elements.pop()) + float(elements.pop()) * 1j
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if not absolute:
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control1 += current_pos
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control2 += current_pos
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end += current_pos
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segments.append(CubicBezier(current_pos, control1, control2, end))
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current_pos = end
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elif command == 'S':
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# Smooth curve. First control point is the "reflection" of
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# the second control point in the previous path.
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if last_command not in 'CS':
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# If there is no previous command or if the previous command
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# was not an C, c, S or s, assume the first control point is
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# coincident with the current point.
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control1 = current_pos
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else:
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# The first control point is assumed to be the reflection of
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# the second control point on the previous command relative
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# to the current point.
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control1 = current_pos + current_pos - segments[-1].control2
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control2 = float(elements.pop()) + float(elements.pop()) * 1j
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end = float(elements.pop()) + float(elements.pop()) * 1j
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if not absolute:
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control2 += current_pos
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end += current_pos
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segments.append(CubicBezier(current_pos, control1, control2, end))
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current_pos = end
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elif command == 'Q':
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control = float(elements.pop()) + float(elements.pop()) * 1j
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end = float(elements.pop()) + float(elements.pop()) * 1j
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if not absolute:
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control += current_pos
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end += current_pos
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segments.append(QuadraticBezier(current_pos, control, end))
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current_pos = end
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elif command == 'T':
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# Smooth curve. Control point is the "reflection" of
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# the second control point in the previous path.
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if last_command not in 'QT':
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# If there is no previous command or if the previous command
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# was not an Q, q, T or t, assume the first control point is
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# coincident with the current point.
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control = current_pos
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else:
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# The control point is assumed to be the reflection of
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# the control point on the previous command relative
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# to the current point.
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control = current_pos + current_pos - segments[-1].control
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end = float(elements.pop()) + float(elements.pop()) * 1j
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if not absolute:
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end += current_pos
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segments.append(QuadraticBezier(current_pos, control, end))
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current_pos = end
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elif command == 'A':
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radius = float(elements.pop()) + float(elements.pop()) * 1j
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rotation = float(elements.pop())
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arc = float(elements.pop())
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sweep = float(elements.pop())
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end = float(elements.pop()) + float(elements.pop()) * 1j
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if not absolute:
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end += current_pos
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segments.append(Arc(current_pos, radius, rotation, arc, sweep, end))
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current_pos = end
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return segments
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