I am done

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from fontTools.pens.transformPen import TransformPen
from fontTools.misc import etree
from fontTools.misc.textTools import tostr
from .parser import parse_path
from .shapes import PathBuilder
__all__ = [tostr(s) for s in ("SVGPath", "parse_path")]
class SVGPath(object):
"""Parse SVG ``path`` elements from a file or string, and draw them
onto a glyph object that supports the FontTools Pen protocol.
For example, reading from an SVG file and drawing to a Defcon Glyph:
.. code-block::
import defcon
glyph = defcon.Glyph()
pen = glyph.getPen()
svg = SVGPath("path/to/a.svg")
svg.draw(pen)
Or reading from a string containing SVG data, using the alternative
'fromstring' (a class method):
.. code-block::
data = '<?xml version="1.0" ...'
svg = SVGPath.fromstring(data)
svg.draw(pen)
Both constructors can optionally take a 'transform' matrix (6-float
tuple, or a FontTools Transform object) to modify the draw output.
"""
def __init__(self, filename=None, transform=None):
if filename is None:
self.root = etree.ElementTree()
else:
tree = etree.parse(filename)
self.root = tree.getroot()
self.transform = transform
@classmethod
def fromstring(cls, data, transform=None):
self = cls(transform=transform)
self.root = etree.fromstring(data)
return self
def draw(self, pen):
if self.transform:
pen = TransformPen(pen, self.transform)
pb = PathBuilder()
# xpath | doesn't seem to reliable work so just walk it
for el in self.root.iter():
pb.add_path_from_element(el)
original_pen = pen
for path, transform in zip(pb.paths, pb.transforms):
if transform:
pen = TransformPen(original_pen, transform)
else:
pen = original_pen
parse_path(path, pen)

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"""Convert SVG Path's elliptical arcs to Bezier curves.
The code is mostly adapted from Blink's SVGPathNormalizer::DecomposeArcToCubic
https://github.com/chromium/chromium/blob/93831f2/third_party/
blink/renderer/core/svg/svg_path_parser.cc#L169-L278
"""
from fontTools.misc.transform import Identity, Scale
from math import atan2, ceil, cos, fabs, isfinite, pi, radians, sin, sqrt, tan
TWO_PI = 2 * pi
PI_OVER_TWO = 0.5 * pi
def _map_point(matrix, pt):
# apply Transform matrix to a point represented as a complex number
r = matrix.transformPoint((pt.real, pt.imag))
return r[0] + r[1] * 1j
class EllipticalArc(object):
def __init__(self, current_point, rx, ry, rotation, large, sweep, target_point):
self.current_point = current_point
self.rx = rx
self.ry = ry
self.rotation = rotation
self.large = large
self.sweep = sweep
self.target_point = target_point
# SVG arc's rotation angle is expressed in degrees, whereas Transform.rotate
# uses radians
self.angle = radians(rotation)
# these derived attributes are computed by the _parametrize method
self.center_point = self.theta1 = self.theta2 = self.theta_arc = None
def _parametrize(self):
# convert from endopoint to center parametrization:
# https://www.w3.org/TR/SVG/implnote.html#ArcConversionEndpointToCenter
# If rx = 0 or ry = 0 then this arc is treated as a straight line segment (a
# "lineto") joining the endpoints.
# http://www.w3.org/TR/SVG/implnote.html#ArcOutOfRangeParameters
rx = fabs(self.rx)
ry = fabs(self.ry)
if not (rx and ry):
return False
# If the current point and target point for the arc are identical, it should
# be treated as a zero length path. This ensures continuity in animations.
if self.target_point == self.current_point:
return False
mid_point_distance = (self.current_point - self.target_point) * 0.5
point_transform = Identity.rotate(-self.angle)
transformed_mid_point = _map_point(point_transform, mid_point_distance)
square_rx = rx * rx
square_ry = ry * ry
square_x = transformed_mid_point.real * transformed_mid_point.real
square_y = transformed_mid_point.imag * transformed_mid_point.imag
# Check if the radii are big enough to draw the arc, scale radii if not.
# http://www.w3.org/TR/SVG/implnote.html#ArcCorrectionOutOfRangeRadii
radii_scale = square_x / square_rx + square_y / square_ry
if radii_scale > 1:
rx *= sqrt(radii_scale)
ry *= sqrt(radii_scale)
self.rx, self.ry = rx, ry
point_transform = Scale(1 / rx, 1 / ry).rotate(-self.angle)
point1 = _map_point(point_transform, self.current_point)
point2 = _map_point(point_transform, self.target_point)
delta = point2 - point1
d = delta.real * delta.real + delta.imag * delta.imag
scale_factor_squared = max(1 / d - 0.25, 0.0)
scale_factor = sqrt(scale_factor_squared)
if self.sweep == self.large:
scale_factor = -scale_factor
delta *= scale_factor
center_point = (point1 + point2) * 0.5
center_point += complex(-delta.imag, delta.real)
point1 -= center_point
point2 -= center_point
theta1 = atan2(point1.imag, point1.real)
theta2 = atan2(point2.imag, point2.real)
theta_arc = theta2 - theta1
if theta_arc < 0 and self.sweep:
theta_arc += TWO_PI
elif theta_arc > 0 and not self.sweep:
theta_arc -= TWO_PI
self.theta1 = theta1
self.theta2 = theta1 + theta_arc
self.theta_arc = theta_arc
self.center_point = center_point
return True
def _decompose_to_cubic_curves(self):
if self.center_point is None and not self._parametrize():
return
point_transform = Identity.rotate(self.angle).scale(self.rx, self.ry)
# Some results of atan2 on some platform implementations are not exact
# enough. So that we get more cubic curves than expected here. Adding 0.001f
# reduces the count of sgements to the correct count.
num_segments = int(ceil(fabs(self.theta_arc / (PI_OVER_TWO + 0.001))))
for i in range(num_segments):
start_theta = self.theta1 + i * self.theta_arc / num_segments
end_theta = self.theta1 + (i + 1) * self.theta_arc / num_segments
t = (4 / 3) * tan(0.25 * (end_theta - start_theta))
if not isfinite(t):
return
sin_start_theta = sin(start_theta)
cos_start_theta = cos(start_theta)
sin_end_theta = sin(end_theta)
cos_end_theta = cos(end_theta)
point1 = complex(
cos_start_theta - t * sin_start_theta,
sin_start_theta + t * cos_start_theta,
)
point1 += self.center_point
target_point = complex(cos_end_theta, sin_end_theta)
target_point += self.center_point
point2 = target_point
point2 += complex(t * sin_end_theta, -t * cos_end_theta)
point1 = _map_point(point_transform, point1)
point2 = _map_point(point_transform, point2)
target_point = _map_point(point_transform, target_point)
yield point1, point2, target_point
def draw(self, pen):
for point1, point2, target_point in self._decompose_to_cubic_curves():
pen.curveTo(
(point1.real, point1.imag),
(point2.real, point2.imag),
(target_point.real, target_point.imag),
)

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# SVG Path specification parser.
# This is an adaptation from 'svg.path' by Lennart Regebro (@regebro),
# modified so that the parser takes a FontTools Pen object instead of
# returning a list of svg.path Path objects.
# The original code can be found at:
# https://github.com/regebro/svg.path/blob/4f9b6e3/src/svg/path/parser.py
# Copyright (c) 2013-2014 Lennart Regebro
# License: MIT
from .arc import EllipticalArc
import re
COMMANDS = set("MmZzLlHhVvCcSsQqTtAa")
ARC_COMMANDS = set("Aa")
UPPERCASE = set("MZLHVCSQTA")
COMMAND_RE = re.compile("([MmZzLlHhVvCcSsQqTtAa])")
# https://www.w3.org/TR/css-syntax-3/#number-token-diagram
# but -6.e-5 will be tokenized as "-6" then "-5" and confuse parsing
FLOAT_RE = re.compile(
r"[-+]?" # optional sign
r"(?:"
r"(?:0|[1-9][0-9]*)(?:\.[0-9]+)?(?:[eE][-+]?[0-9]+)?" # int/float
r"|"
r"(?:\.[0-9]+(?:[eE][-+]?[0-9]+)?)" # float with leading dot (e.g. '.42')
r")"
)
BOOL_RE = re.compile("^[01]")
SEPARATOR_RE = re.compile(f"[, \t]")
def _tokenize_path(pathdef):
arc_cmd = None
for x in COMMAND_RE.split(pathdef):
if x in COMMANDS:
arc_cmd = x if x in ARC_COMMANDS else None
yield x
continue
if arc_cmd:
try:
yield from _tokenize_arc_arguments(x)
except ValueError as e:
raise ValueError(f"Invalid arc command: '{arc_cmd}{x}'") from e
else:
for token in FLOAT_RE.findall(x):
yield token
ARC_ARGUMENT_TYPES = (
("rx", FLOAT_RE),
("ry", FLOAT_RE),
("x-axis-rotation", FLOAT_RE),
("large-arc-flag", BOOL_RE),
("sweep-flag", BOOL_RE),
("x", FLOAT_RE),
("y", FLOAT_RE),
)
def _tokenize_arc_arguments(arcdef):
raw_args = [s for s in SEPARATOR_RE.split(arcdef) if s]
if not raw_args:
raise ValueError(f"Not enough arguments: '{arcdef}'")
raw_args.reverse()
i = 0
while raw_args:
arg = raw_args.pop()
name, pattern = ARC_ARGUMENT_TYPES[i]
match = pattern.search(arg)
if not match:
raise ValueError(f"Invalid argument for '{name}' parameter: {arg!r}")
j, k = match.span()
yield arg[j:k]
arg = arg[k:]
if arg:
raw_args.append(arg)
# wrap around every 7 consecutive arguments
if i == 6:
i = 0
else:
i += 1
if i != 0:
raise ValueError(f"Not enough arguments: '{arcdef}'")
def parse_path(pathdef, pen, current_pos=(0, 0), arc_class=EllipticalArc):
"""Parse SVG path definition (i.e. "d" attribute of <path> elements)
and call a 'pen' object's moveTo, lineTo, curveTo, qCurveTo and closePath
methods.
If 'current_pos' (2-float tuple) is provided, the initial moveTo will
be relative to that instead being absolute.
If the pen has an "arcTo" method, it is called with the original values
of the elliptical arc curve commands:
.. code-block::
pen.arcTo(rx, ry, rotation, arc_large, arc_sweep, (x, y))
Otherwise, the arcs are approximated by series of cubic Bezier segments
("curveTo"), one every 90 degrees.
"""
# In the SVG specs, initial movetos are absolute, even if
# specified as 'm'. This is the default behavior here as well.
# But if you pass in a current_pos variable, the initial moveto
# will be relative to that current_pos. This is useful.
current_pos = complex(*current_pos)
elements = list(_tokenize_path(pathdef))
# Reverse for easy use of .pop()
elements.reverse()
start_pos = None
command = None
last_control = None
have_arcTo = hasattr(pen, "arcTo")
while elements:
if elements[-1] in COMMANDS:
# New command.
last_command = command # Used by S and T
command = elements.pop()
absolute = command in UPPERCASE
command = command.upper()
else:
# If this element starts with numbers, it is an implicit command
# and we don't change the command. Check that it's allowed:
if command is None:
raise ValueError(
"Unallowed implicit command in %s, position %s"
% (pathdef, len(pathdef.split()) - len(elements))
)
last_command = command # Used by S and T
if command == "M":
# Moveto command.
x = elements.pop()
y = elements.pop()
pos = float(x) + float(y) * 1j
if absolute:
current_pos = pos
else:
current_pos += pos
# M is not preceded by Z; it's an open subpath
if start_pos is not None:
pen.endPath()
pen.moveTo((current_pos.real, current_pos.imag))
# when M is called, reset start_pos
# This behavior of Z is defined in svg spec:
# http://www.w3.org/TR/SVG/paths.html#PathDataClosePathCommand
start_pos = current_pos
# Implicit moveto commands are treated as lineto commands.
# So we set command to lineto here, in case there are
# further implicit commands after this moveto.
command = "L"
elif command == "Z":
# Close path
if current_pos != start_pos:
pen.lineTo((start_pos.real, start_pos.imag))
pen.closePath()
current_pos = start_pos
start_pos = None
command = None # You can't have implicit commands after closing.
elif command == "L":
x = elements.pop()
y = elements.pop()
pos = float(x) + float(y) * 1j
if not absolute:
pos += current_pos
pen.lineTo((pos.real, pos.imag))
current_pos = pos
elif command == "H":
x = elements.pop()
pos = float(x) + current_pos.imag * 1j
if not absolute:
pos += current_pos.real
pen.lineTo((pos.real, pos.imag))
current_pos = pos
elif command == "V":
y = elements.pop()
pos = current_pos.real + float(y) * 1j
if not absolute:
pos += current_pos.imag * 1j
pen.lineTo((pos.real, pos.imag))
current_pos = pos
elif command == "C":
control1 = float(elements.pop()) + float(elements.pop()) * 1j
control2 = float(elements.pop()) + float(elements.pop()) * 1j
end = float(elements.pop()) + float(elements.pop()) * 1j
if not absolute:
control1 += current_pos
control2 += current_pos
end += current_pos
pen.curveTo(
(control1.real, control1.imag),
(control2.real, control2.imag),
(end.real, end.imag),
)
current_pos = end
last_control = control2
elif command == "S":
# Smooth curve. First control point is the "reflection" of
# the second control point in the previous path.
if last_command not in "CS":
# If there is no previous command or if the previous command
# was not an C, c, S or s, assume the first control point is
# coincident with the current point.
control1 = current_pos
else:
# The first control point is assumed to be the reflection of
# the second control point on the previous command relative
# to the current point.
control1 = current_pos + current_pos - last_control
control2 = float(elements.pop()) + float(elements.pop()) * 1j
end = float(elements.pop()) + float(elements.pop()) * 1j
if not absolute:
control2 += current_pos
end += current_pos
pen.curveTo(
(control1.real, control1.imag),
(control2.real, control2.imag),
(end.real, end.imag),
)
current_pos = end
last_control = control2
elif command == "Q":
control = float(elements.pop()) + float(elements.pop()) * 1j
end = float(elements.pop()) + float(elements.pop()) * 1j
if not absolute:
control += current_pos
end += current_pos
pen.qCurveTo((control.real, control.imag), (end.real, end.imag))
current_pos = end
last_control = control
elif command == "T":
# Smooth curve. Control point is the "reflection" of
# the second control point in the previous path.
if last_command not in "QT":
# If there is no previous command or if the previous command
# was not an Q, q, T or t, assume the first control point is
# coincident with the current point.
control = current_pos
else:
# The control point is assumed to be the reflection of
# the control point on the previous command relative
# to the current point.
control = current_pos + current_pos - last_control
end = float(elements.pop()) + float(elements.pop()) * 1j
if not absolute:
end += current_pos
pen.qCurveTo((control.real, control.imag), (end.real, end.imag))
current_pos = end
last_control = control
elif command == "A":
rx = abs(float(elements.pop()))
ry = abs(float(elements.pop()))
rotation = float(elements.pop())
arc_large = bool(int(elements.pop()))
arc_sweep = bool(int(elements.pop()))
end = float(elements.pop()) + float(elements.pop()) * 1j
if not absolute:
end += current_pos
# if the pen supports arcs, pass the values unchanged, otherwise
# approximate the arc with a series of cubic bezier curves
if have_arcTo:
pen.arcTo(
rx,
ry,
rotation,
arc_large,
arc_sweep,
(end.real, end.imag),
)
else:
arc = arc_class(
current_pos, rx, ry, rotation, arc_large, arc_sweep, end
)
arc.draw(pen)
current_pos = end
# no final Z command, it's an open path
if start_pos is not None:
pen.endPath()

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import re
def _prefer_non_zero(*args):
for arg in args:
if arg != 0:
return arg
return 0.0
def _ntos(n):
# %f likes to add unnecessary 0's, %g isn't consistent about # decimals
return ("%.3f" % n).rstrip("0").rstrip(".")
def _strip_xml_ns(tag):
# ElementTree API doesn't provide a way to ignore XML namespaces in tags
# so we here strip them ourselves: cf. https://bugs.python.org/issue18304
return tag.split("}", 1)[1] if "}" in tag else tag
def _transform(raw_value):
# TODO assumes a 'matrix' transform.
# No other transform functions are supported at the moment.
# https://developer.mozilla.org/en-US/docs/Web/SVG/Attribute/transform
# start simple: if you aren't exactly matrix(...) then no love
match = re.match(r"matrix\((.*)\)", raw_value)
if not match:
raise NotImplementedError
matrix = tuple(float(p) for p in re.split(r"\s+|,", match.group(1)))
if len(matrix) != 6:
raise ValueError("wrong # of terms in %s" % raw_value)
return matrix
class PathBuilder(object):
def __init__(self):
self.paths = []
self.transforms = []
def _start_path(self, initial_path=""):
self.paths.append(initial_path)
self.transforms.append(None)
def _end_path(self):
self._add("z")
def _add(self, path_snippet):
path = self.paths[-1]
if path:
path += " " + path_snippet
else:
path = path_snippet
self.paths[-1] = path
def _move(self, c, x, y):
self._add("%s%s,%s" % (c, _ntos(x), _ntos(y)))
def M(self, x, y):
self._move("M", x, y)
def m(self, x, y):
self._move("m", x, y)
def _arc(self, c, rx, ry, x, y, large_arc):
self._add(
"%s%s,%s 0 %d 1 %s,%s"
% (c, _ntos(rx), _ntos(ry), large_arc, _ntos(x), _ntos(y))
)
def A(self, rx, ry, x, y, large_arc=0):
self._arc("A", rx, ry, x, y, large_arc)
def a(self, rx, ry, x, y, large_arc=0):
self._arc("a", rx, ry, x, y, large_arc)
def _vhline(self, c, x):
self._add("%s%s" % (c, _ntos(x)))
def H(self, x):
self._vhline("H", x)
def h(self, x):
self._vhline("h", x)
def V(self, y):
self._vhline("V", y)
def v(self, y):
self._vhline("v", y)
def _line(self, c, x, y):
self._add("%s%s,%s" % (c, _ntos(x), _ntos(y)))
def L(self, x, y):
self._line("L", x, y)
def l(self, x, y):
self._line("l", x, y)
def _parse_line(self, line):
x1 = float(line.attrib.get("x1", 0))
y1 = float(line.attrib.get("y1", 0))
x2 = float(line.attrib.get("x2", 0))
y2 = float(line.attrib.get("y2", 0))
self._start_path()
self.M(x1, y1)
self.L(x2, y2)
def _parse_rect(self, rect):
x = float(rect.attrib.get("x", 0))
y = float(rect.attrib.get("y", 0))
w = float(rect.attrib.get("width"))
h = float(rect.attrib.get("height"))
rx = float(rect.attrib.get("rx", 0))
ry = float(rect.attrib.get("ry", 0))
rx = _prefer_non_zero(rx, ry)
ry = _prefer_non_zero(ry, rx)
# TODO there are more rules for adjusting rx, ry
self._start_path()
self.M(x + rx, y)
self.H(x + w - rx)
if rx > 0:
self.A(rx, ry, x + w, y + ry)
self.V(y + h - ry)
if rx > 0:
self.A(rx, ry, x + w - rx, y + h)
self.H(x + rx)
if rx > 0:
self.A(rx, ry, x, y + h - ry)
self.V(y + ry)
if rx > 0:
self.A(rx, ry, x + rx, y)
self._end_path()
def _parse_path(self, path):
if "d" in path.attrib:
self._start_path(initial_path=path.attrib["d"])
def _parse_polygon(self, poly):
if "points" in poly.attrib:
self._start_path("M" + poly.attrib["points"])
self._end_path()
def _parse_polyline(self, poly):
if "points" in poly.attrib:
self._start_path("M" + poly.attrib["points"])
def _parse_circle(self, circle):
cx = float(circle.attrib.get("cx", 0))
cy = float(circle.attrib.get("cy", 0))
r = float(circle.attrib.get("r"))
# arc doesn't seem to like being a complete shape, draw two halves
self._start_path()
self.M(cx - r, cy)
self.A(r, r, cx + r, cy, large_arc=1)
self.A(r, r, cx - r, cy, large_arc=1)
def _parse_ellipse(self, ellipse):
cx = float(ellipse.attrib.get("cx", 0))
cy = float(ellipse.attrib.get("cy", 0))
rx = float(ellipse.attrib.get("rx"))
ry = float(ellipse.attrib.get("ry"))
# arc doesn't seem to like being a complete shape, draw two halves
self._start_path()
self.M(cx - rx, cy)
self.A(rx, ry, cx + rx, cy, large_arc=1)
self.A(rx, ry, cx - rx, cy, large_arc=1)
def add_path_from_element(self, el):
tag = _strip_xml_ns(el.tag)
parse_fn = getattr(self, "_parse_%s" % tag.lower(), None)
if not callable(parse_fn):
return False
parse_fn(el)
if "transform" in el.attrib:
self.transforms[-1] = _transform(el.attrib["transform"])
return True