106 lines
3.9 KiB
Python
106 lines
3.9 KiB
Python
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# Copyright 2016 Google Inc. All Rights Reserved.
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# Copyright 2023 Behdad Esfahbod. All Rights Reserved.
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#
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# Licensed under the Apache License, Version 2.0 (the "License");
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# you may not use this file except in compliance with the License.
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# You may obtain a copy of the License at
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#
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# http://www.apache.org/licenses/LICENSE-2.0
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#
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# Unless required by applicable law or agreed to in writing, software
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# distributed under the License is distributed on an "AS IS" BASIS,
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# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
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# See the License for the specific language governing permissions and
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# limitations under the License.
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from fontTools.qu2cu import quadratic_to_curves
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from fontTools.pens.filterPen import ContourFilterPen
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from fontTools.pens.reverseContourPen import ReverseContourPen
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import math
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class Qu2CuPen(ContourFilterPen):
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"""A filter pen to convert quadratic bezier splines to cubic curves
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using the FontTools SegmentPen protocol.
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Args:
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other_pen: another SegmentPen used to draw the transformed outline.
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max_err: maximum approximation error in font units. For optimal results,
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if you know the UPEM of the font, we recommend setting this to a
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value equal, or close to UPEM / 1000.
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reverse_direction: flip the contours' direction but keep starting point.
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stats: a dictionary counting the point numbers of cubic segments.
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"""
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def __init__(
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self,
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other_pen,
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max_err,
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all_cubic=False,
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reverse_direction=False,
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stats=None,
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):
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if reverse_direction:
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other_pen = ReverseContourPen(other_pen)
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super().__init__(other_pen)
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self.all_cubic = all_cubic
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self.max_err = max_err
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self.stats = stats
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def _quadratics_to_curve(self, q):
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curves = quadratic_to_curves(q, self.max_err, all_cubic=self.all_cubic)
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if self.stats is not None:
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for curve in curves:
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n = str(len(curve) - 2)
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self.stats[n] = self.stats.get(n, 0) + 1
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for curve in curves:
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if len(curve) == 4:
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yield ("curveTo", curve[1:])
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else:
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yield ("qCurveTo", curve[1:])
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def filterContour(self, contour):
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quadratics = []
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currentPt = None
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newContour = []
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for op, args in contour:
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if op == "qCurveTo" and (
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self.all_cubic or (len(args) > 2 and args[-1] is not None)
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):
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if args[-1] is None:
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raise NotImplementedError(
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"oncurve-less contours with all_cubic not implemented"
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)
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quadratics.append((currentPt,) + args)
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else:
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if quadratics:
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newContour.extend(self._quadratics_to_curve(quadratics))
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quadratics = []
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newContour.append((op, args))
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currentPt = args[-1] if args else None
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if quadratics:
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newContour.extend(self._quadratics_to_curve(quadratics))
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if not self.all_cubic:
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# Add back implicit oncurve points
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contour = newContour
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newContour = []
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for op, args in contour:
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if op == "qCurveTo" and newContour and newContour[-1][0] == "qCurveTo":
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pt0 = newContour[-1][1][-2]
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pt1 = newContour[-1][1][-1]
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pt2 = args[0]
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if (
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pt1 is not None
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and math.isclose(pt2[0] - pt1[0], pt1[0] - pt0[0])
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and math.isclose(pt2[1] - pt1[1], pt1[1] - pt0[1])
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):
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newArgs = newContour[-1][1][:-1] + args
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newContour[-1] = (op, newArgs)
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continue
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newContour.append((op, args))
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return newContour
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