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Diffstat (limited to 'Lib/fontTools/pens/qu2cuPen.py')
-rw-r--r-- | Lib/fontTools/pens/qu2cuPen.py | 105 |
1 files changed, 105 insertions, 0 deletions
diff --git a/Lib/fontTools/pens/qu2cuPen.py b/Lib/fontTools/pens/qu2cuPen.py new file mode 100644 index 00000000..7e400f98 --- /dev/null +++ b/Lib/fontTools/pens/qu2cuPen.py @@ -0,0 +1,105 @@ +# Copyright 2016 Google Inc. All Rights Reserved. +# Copyright 2023 Behdad Esfahbod. All Rights Reserved. +# +# Licensed under the Apache License, Version 2.0 (the "License"); +# you may not use this file except in compliance with the License. +# You may obtain a copy of the License at +# +# http://www.apache.org/licenses/LICENSE-2.0 +# +# Unless required by applicable law or agreed to in writing, software +# distributed under the License is distributed on an "AS IS" BASIS, +# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. +# See the License for the specific language governing permissions and +# limitations under the License. + +from fontTools.qu2cu import quadratic_to_curves +from fontTools.pens.filterPen import ContourFilterPen +from fontTools.pens.reverseContourPen import ReverseContourPen +import math + + +class Qu2CuPen(ContourFilterPen): + """A filter pen to convert quadratic bezier splines to cubic curves + using the FontTools SegmentPen protocol. + + Args: + + other_pen: another SegmentPen used to draw the transformed outline. + max_err: maximum approximation error in font units. For optimal results, + if you know the UPEM of the font, we recommend setting this to a + value equal, or close to UPEM / 1000. + reverse_direction: flip the contours' direction but keep starting point. + stats: a dictionary counting the point numbers of cubic segments. + """ + + def __init__( + self, + other_pen, + max_err, + all_cubic=False, + reverse_direction=False, + stats=None, + ): + if reverse_direction: + other_pen = ReverseContourPen(other_pen) + super().__init__(other_pen) + self.all_cubic = all_cubic + self.max_err = max_err + self.stats = stats + + def _quadratics_to_curve(self, q): + curves = quadratic_to_curves(q, self.max_err, all_cubic=self.all_cubic) + if self.stats is not None: + for curve in curves: + n = str(len(curve) - 2) + self.stats[n] = self.stats.get(n, 0) + 1 + for curve in curves: + if len(curve) == 4: + yield ("curveTo", curve[1:]) + else: + yield ("qCurveTo", curve[1:]) + + def filterContour(self, contour): + quadratics = [] + currentPt = None + newContour = [] + for op, args in contour: + if op == "qCurveTo" and ( + self.all_cubic or (len(args) > 2 and args[-1] is not None) + ): + if args[-1] is None: + raise NotImplementedError( + "oncurve-less contours with all_cubic not implemented" + ) + quadratics.append((currentPt,) + args) + else: + if quadratics: + newContour.extend(self._quadratics_to_curve(quadratics)) + quadratics = [] + newContour.append((op, args)) + currentPt = args[-1] if args else None + if quadratics: + newContour.extend(self._quadratics_to_curve(quadratics)) + + if not self.all_cubic: + # Add back implicit oncurve points + contour = newContour + newContour = [] + for op, args in contour: + if op == "qCurveTo" and newContour and newContour[-1][0] == "qCurveTo": + pt0 = newContour[-1][1][-2] + pt1 = newContour[-1][1][-1] + pt2 = args[0] + if ( + pt1 is not None + and math.isclose(pt2[0] - pt1[0], pt1[0] - pt0[0]) + and math.isclose(pt2[1] - pt1[1], pt1[1] - pt0[1]) + ): + newArgs = newContour[-1][1][:-1] + args + newContour[-1] = (op, newArgs) + continue + + newContour.append((op, args)) + + return newContour |