66 lines
2.3 KiB
Python
66 lines
2.3 KiB
Python
# 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 FilterPen
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from fontTools.pens.reverseContourPen import ReverseContourPen
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class Qu2CuPen(FilterPen):
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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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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.max_err = max_err
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self.stats = stats
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def _quadratic_to_curve(self, points):
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quadratics = (self.current_pt,) + points
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curves = quadratic_to_curves(quadratics, self.max_err)
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if self.stats is not None:
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n = str(len(curves))
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self.stats[n] = self.stats.get(n, 0) + 1
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if len(quadratics) <= len(curves) * 3:
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super().qCurveTo(*quadratics)
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else:
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for curve in curves:
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self.curveTo(*curve[1:])
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def qCurveTo(self, *points):
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n = len(points)
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if n <= 3:
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super().qCurveTo(*points)
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else:
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self._quadratic_to_curve(points)
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