| # Copyright 2016 Google Inc. 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. |
| |
| import operator |
| from fontTools.cu2qu import curve_to_quadratic, curves_to_quadratic |
| from fontTools.pens.basePen import decomposeSuperBezierSegment |
| from fontTools.pens.filterPen import FilterPen |
| from fontTools.pens.reverseContourPen import ReverseContourPen |
| from fontTools.pens.pointPen import BasePointToSegmentPen |
| from fontTools.pens.pointPen import ReverseContourPointPen |
| |
| |
| class Cu2QuPen(FilterPen): |
| """A filter pen to convert cubic bezier curves to quadratic b-splines |
| 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 quadratic segments. |
| all_quadratic: if True (default), only quadratic b-splines are generated. |
| if False, quadratic curves or cubic curves are generated depending |
| on which one is more economical. |
| """ |
| |
| def __init__( |
| self, |
| other_pen, |
| max_err, |
| reverse_direction=False, |
| stats=None, |
| all_quadratic=True, |
| ): |
| if reverse_direction: |
| other_pen = ReverseContourPen(other_pen) |
| super().__init__(other_pen) |
| self.max_err = max_err |
| self.stats = stats |
| self.all_quadratic = all_quadratic |
| |
| def _convert_curve(self, pt1, pt2, pt3): |
| curve = (self.current_pt, pt1, pt2, pt3) |
| result = curve_to_quadratic(curve, self.max_err, self.all_quadratic) |
| if self.stats is not None: |
| n = str(len(result) - 2) |
| self.stats[n] = self.stats.get(n, 0) + 1 |
| if self.all_quadratic: |
| self.qCurveTo(*result[1:]) |
| else: |
| if len(result) == 3: |
| self.qCurveTo(*result[1:]) |
| else: |
| assert len(result) == 4 |
| super().curveTo(*result[1:]) |
| |
| def curveTo(self, *points): |
| n = len(points) |
| if n == 3: |
| # this is the most common case, so we special-case it |
| self._convert_curve(*points) |
| elif n > 3: |
| for segment in decomposeSuperBezierSegment(points): |
| self._convert_curve(*segment) |
| else: |
| self.qCurveTo(*points) |
| |
| |
| class Cu2QuPointPen(BasePointToSegmentPen): |
| """A filter pen to convert cubic bezier curves to quadratic b-splines |
| using the FontTools PointPen protocol. |
| |
| Args: |
| other_point_pen: another PointPen 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: reverse the winding direction of all contours. |
| stats: a dictionary counting the point numbers of quadratic segments. |
| all_quadratic: if True (default), only quadratic b-splines are generated. |
| if False, quadratic curves or cubic curves are generated depending |
| on which one is more economical. |
| """ |
| |
| __points_required = { |
| "move": (1, operator.eq), |
| "line": (1, operator.eq), |
| "qcurve": (2, operator.ge), |
| "curve": (3, operator.eq), |
| } |
| |
| def __init__( |
| self, |
| other_point_pen, |
| max_err, |
| reverse_direction=False, |
| stats=None, |
| all_quadratic=True, |
| ): |
| BasePointToSegmentPen.__init__(self) |
| if reverse_direction: |
| self.pen = ReverseContourPointPen(other_point_pen) |
| else: |
| self.pen = other_point_pen |
| self.max_err = max_err |
| self.stats = stats |
| self.all_quadratic = all_quadratic |
| |
| def _flushContour(self, segments): |
| assert len(segments) >= 1 |
| closed = segments[0][0] != "move" |
| new_segments = [] |
| prev_points = segments[-1][1] |
| prev_on_curve = prev_points[-1][0] |
| for segment_type, points in segments: |
| if segment_type == "curve": |
| for sub_points in self._split_super_bezier_segments(points): |
| on_curve, smooth, name, kwargs = sub_points[-1] |
| bcp1, bcp2 = sub_points[0][0], sub_points[1][0] |
| cubic = [prev_on_curve, bcp1, bcp2, on_curve] |
| quad = curve_to_quadratic(cubic, self.max_err, self.all_quadratic) |
| if self.stats is not None: |
| n = str(len(quad) - 2) |
| self.stats[n] = self.stats.get(n, 0) + 1 |
| new_points = [(pt, False, None, {}) for pt in quad[1:-1]] |
| new_points.append((on_curve, smooth, name, kwargs)) |
| if self.all_quadratic or len(new_points) == 2: |
| new_segments.append(["qcurve", new_points]) |
| else: |
| new_segments.append(["curve", new_points]) |
| prev_on_curve = sub_points[-1][0] |
| else: |
| new_segments.append([segment_type, points]) |
| prev_on_curve = points[-1][0] |
| if closed: |
| # the BasePointToSegmentPen.endPath method that calls _flushContour |
| # rotates the point list of closed contours so that they end with |
| # the first on-curve point. We restore the original starting point. |
| new_segments = new_segments[-1:] + new_segments[:-1] |
| self._drawPoints(new_segments) |
| |
| def _split_super_bezier_segments(self, points): |
| sub_segments = [] |
| # n is the number of control points |
| n = len(points) - 1 |
| if n == 2: |
| # a simple bezier curve segment |
| sub_segments.append(points) |
| elif n > 2: |
| # a "super" bezier; decompose it |
| on_curve, smooth, name, kwargs = points[-1] |
| num_sub_segments = n - 1 |
| for i, sub_points in enumerate( |
| decomposeSuperBezierSegment([pt for pt, _, _, _ in points]) |
| ): |
| new_segment = [] |
| for point in sub_points[:-1]: |
| new_segment.append((point, False, None, {})) |
| if i == (num_sub_segments - 1): |
| # the last on-curve keeps its original attributes |
| new_segment.append((on_curve, smooth, name, kwargs)) |
| else: |
| # on-curves of sub-segments are always "smooth" |
| new_segment.append((sub_points[-1], True, None, {})) |
| sub_segments.append(new_segment) |
| else: |
| raise AssertionError("expected 2 control points, found: %d" % n) |
| return sub_segments |
| |
| def _drawPoints(self, segments): |
| pen = self.pen |
| pen.beginPath() |
| last_offcurves = [] |
| points_required = self.__points_required |
| for i, (segment_type, points) in enumerate(segments): |
| if segment_type in points_required: |
| n, op = points_required[segment_type] |
| assert op(len(points), n), ( |
| f"illegal {segment_type!r} segment point count: " |
| f"expected {n}, got {len(points)}" |
| ) |
| offcurves = points[:-1] |
| if i == 0: |
| # any off-curve points preceding the first on-curve |
| # will be appended at the end of the contour |
| last_offcurves = offcurves |
| else: |
| for pt, smooth, name, kwargs in offcurves: |
| pen.addPoint(pt, None, smooth, name, **kwargs) |
| pt, smooth, name, kwargs = points[-1] |
| if pt is None: |
| assert segment_type == "qcurve" |
| # special quadratic contour with no on-curve points: |
| # we need to skip the "None" point. See also the Pen |
| # protocol's qCurveTo() method and fontTools.pens.basePen |
| pass |
| else: |
| pen.addPoint(pt, segment_type, smooth, name, **kwargs) |
| else: |
| raise AssertionError("unexpected segment type: %r" % segment_type) |
| for pt, smooth, name, kwargs in last_offcurves: |
| pen.addPoint(pt, None, smooth, name, **kwargs) |
| pen.endPath() |
| |
| def addComponent(self, baseGlyphName, transformation): |
| assert self.currentPath is None |
| self.pen.addComponent(baseGlyphName, transformation) |
| |
| |
| class Cu2QuMultiPen: |
| """A filter multi-pen to convert cubic bezier curves to quadratic b-splines |
| in a interpolation-compatible manner, using the FontTools SegmentPen protocol. |
| |
| Args: |
| |
| other_pens: list of SegmentPens used to draw the transformed outlines. |
| 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. |
| |
| This pen does not follow the normal SegmentPen protocol. Instead, its |
| moveTo/lineTo/qCurveTo/curveTo methods take a list of tuples that are |
| arguments that would normally be passed to a SegmentPen, one item for |
| each of the pens in other_pens. |
| """ |
| |
| # TODO Simplify like 3e8ebcdce592fe8a59ca4c3a294cc9724351e1ce |
| # Remove start_pts and _add_moveTO |
| |
| def __init__(self, other_pens, max_err, reverse_direction=False): |
| if reverse_direction: |
| other_pens = [ |
| ReverseContourPen(pen, outputImpliedClosingLine=True) |
| for pen in other_pens |
| ] |
| self.pens = other_pens |
| self.max_err = max_err |
| self.start_pts = None |
| self.current_pts = None |
| |
| def _check_contour_is_open(self): |
| if self.current_pts is None: |
| raise AssertionError("moveTo is required") |
| |
| def _check_contour_is_closed(self): |
| if self.current_pts is not None: |
| raise AssertionError("closePath or endPath is required") |
| |
| def _add_moveTo(self): |
| if self.start_pts is not None: |
| for pt, pen in zip(self.start_pts, self.pens): |
| pen.moveTo(*pt) |
| self.start_pts = None |
| |
| def moveTo(self, pts): |
| self._check_contour_is_closed() |
| self.start_pts = self.current_pts = pts |
| self._add_moveTo() |
| |
| def lineTo(self, pts): |
| self._check_contour_is_open() |
| self._add_moveTo() |
| for pt, pen in zip(pts, self.pens): |
| pen.lineTo(*pt) |
| self.current_pts = pts |
| |
| def qCurveTo(self, pointsList): |
| self._check_contour_is_open() |
| if len(pointsList[0]) == 1: |
| self.lineTo([(points[0],) for points in pointsList]) |
| return |
| self._add_moveTo() |
| current_pts = [] |
| for points, pen in zip(pointsList, self.pens): |
| pen.qCurveTo(*points) |
| current_pts.append((points[-1],)) |
| self.current_pts = current_pts |
| |
| def _curves_to_quadratic(self, pointsList): |
| curves = [] |
| for current_pt, points in zip(self.current_pts, pointsList): |
| curves.append(current_pt + points) |
| quadratics = curves_to_quadratic(curves, [self.max_err] * len(curves)) |
| pointsList = [] |
| for quadratic in quadratics: |
| pointsList.append(quadratic[1:]) |
| self.qCurveTo(pointsList) |
| |
| def curveTo(self, pointsList): |
| self._check_contour_is_open() |
| self._curves_to_quadratic(pointsList) |
| |
| def closePath(self): |
| self._check_contour_is_open() |
| if self.start_pts is None: |
| for pen in self.pens: |
| pen.closePath() |
| self.current_pts = self.start_pts = None |
| |
| def endPath(self): |
| self._check_contour_is_open() |
| if self.start_pts is None: |
| for pen in self.pens: |
| pen.endPath() |
| self.current_pts = self.start_pts = None |
| |
| def addComponent(self, glyphName, transformations): |
| self._check_contour_is_closed() |
| for trans, pen in zip(transformations, self.pens): |
| pen.addComponent(glyphName, trans) |
