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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
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