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| # 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 | |