def getExtremes(self, point=Tuple[int, ...]) -> list:
# gets extremes of a cubic bezier curve
pt1, pt2, pt3, pt4 = point
(ax, ay), (bx, by), (cx, cy), _ = calcCubicParameters(pt1, pt2, pt3, pt4)
ax3 = ax * 3.0
ay3 = ay * 3.0
bx2 = bx * 2.0
by2 = by * 2.0
collector: list = []
if self.horizontal:
collector += [t for t in solveQuadratic(ax3, bx2, cx) if 0 <= t < 1]
if self.vertical:
collector += [t for t in solveQuadratic(ay3, by2, cy) if 0 <= t < 1]
return sorted(collector)
def getExtremaForCubic(pt1, pt2, pt3, pt4, h=True, v=False): (ax, ay), (bx, by), c, d = calcCubicParameters(pt1, pt2, pt3, pt4) ax *= 3.0 ay *= 3.0 bx *= 2.0 by *= 2.0 h_roots = [] v_roots = [] if h: h_roots = [t for t in solveQuadratic(ay, by, c[1]) if 0 < t < 1] if v: v_roots = [t for t in solveQuadratic(ax, bx, c[0]) if 0 < t < 1] roots = h_roots + v_roots return [p[3] for p in splitCubicAtT(pt1, pt2, pt3, pt4, *roots)[:-1]]
def getExtremaForCubic(pt1, pt2, pt3, pt4, h=True, v=False):
(ax, ay), (bx, by), c, d = calcCubicParameters(pt1, pt2, pt3, pt4)
ax *= 3.0
ay *= 3.0
bx *= 2.0
by *= 2.0
h_roots = []
v_roots = []
if h:
h_roots = [t for t in solveQuadratic(ay, by, c[1]) if 0 < t < 1]
if v:
v_roots = [t for t in solveQuadratic(ax, bx, c[0]) if 0 < t < 1]
roots = h_roots + v_roots
return [p[3] for p in splitCubicAtT(pt1, pt2, pt3, pt4, *roots)[:-1]]
def _tValueForPointOnQuadCurve(point, pts, isHorizontal=0):
quadSegments = decomposeQuadraticSegment(pts[1:])
previousOnCurve = pts[0]
solutionsDict = dict()
for index, (pt1, pt2) in enumerate(quadSegments):
a, b, c = bezierTools.calcQuadraticParameters(previousOnCurve, pt1,
pt2)
subSolutions = bezierTools.solveQuadratic(
a[isHorizontal], b[isHorizontal],
c[isHorizontal] - point[isHorizontal])
subSolutions = [t for t in subSolutions if 0 <= t < 1]
for t in subSolutions:
solutionsDict[(t, index)] = _getQuadPoint(t, previousOnCurve, pt1,
pt2)
previousOnCurve = pt2
solutions = solutionsDict.keys()
if not solutions and not isHorizontal:
return _tValueForPointOnQuadCurve(point, pts, isHorizontal=1)
if len(solutions) > 1:
intersectionLenghts = {}
for t in solutions:
tp = solutionsDict[t]
dist = _distance(tp, point)
intersectionLenghts[dist] = t
minDist = min(intersectionLenghts.keys())
solutions = [intersectionLenghts[minDist]]
return solutions
def getExtremaForCubic(pt1, pt2, pt3, pt4, h=True, v=False): (ax, ay), (bx, by), c, d = calcCubicParameters(pt1, pt2, pt3, pt4) ax *= 3.0 ay *= 3.0 bx *= 2.0 by *= 2.0 points = [] vectors = [] if h: roots = [t for t in solveQuadratic(ay, by, c[1]) if 0 < t < 1] points, vectors = get_extrema_points_vectors(roots, pt1, pt2, pt3, pt4) if v: roots = [t for t in solveQuadratic(ax, bx, c[0]) if 0 < t < 1] v_points, v_vectors = get_extrema_points_vectors(roots, pt1, pt2, pt3, pt4) points += v_points vectors += v_vectors return points, vectors
def getExtremaForCubic(pt1, pt2, pt3, pt4, h=True, v=False):
(ax, ay), (bx, by), c, d = calcCubicParameters(pt1, pt2, pt3, pt4)
ax *= 3.0
ay *= 3.0
bx *= 2.0
by *= 2.0
points = []
vectors = []
if h:
roots = [t for t in solveQuadratic(ay, by, c[1]) if 0 < t < 1]
points, vectors = get_extrema_points_vectors(roots, pt1, pt2, pt3, pt4)
if v:
roots = [t for t in solveQuadratic(ax, bx, c[0]) if 0 < t < 1]
v_points, v_vectors = get_extrema_points_vectors(
roots, pt1, pt2, pt3, pt4)
points += v_points
vectors += v_vectors
return points, vectors
def getExtremaForCubic(
pt0: Point,
pt1: Point,
pt2: Point,
pt3: Point,
h: bool = True,
v: bool = False,
include_start_end: bool = False,
) -> List[float]:
"""
Return a list of t values at which the cubic curve defined by pt0, pt1,
pt2, pt3 has extrema.
:param h: Calculate extrema for horizontal derivative == 0 (= what type
designers call vertical extrema!).
:type h: bool
:param v: Calculate extrema for vertical derivative == 0 (= what type
designers call horizontal extrema!).
:type v: bool
:param include_start_end: Also calculate extrema that lie at the start or
end point of the curve.
:type include_start_end: bool
"""
(ax, ay), (bx, by), c, _d = calcCubicParameters(pt0, pt1, pt2, pt3)
ax *= 3.0
ay *= 3.0
bx *= 2.0
by *= 2.0
roots = []
if include_start_end:
if h:
roots = [t for t in solveQuadratic(ay, by, c[1]) if 0 <= t <= 1]
if v:
roots += [t for t in solveQuadratic(ax, bx, c[0]) if 0 <= t <= 1]
else:
if h:
roots = [t for t in solveQuadratic(ay, by, c[1]) if 0 < t < 1]
if v:
roots += [t for t in solveQuadratic(ax, bx, c[0]) if 0 < t < 1]
return roots
def split_at_extrema(pt1, pt2, pt3, pt4, transform=Transform()):
"""
Add extrema to a cubic curve, after applying a transformation.
Example ::
>>> # A segment in which no extrema will be added.
>>> split_at_extrema((297, 52), (406, 52), (496, 142), (496, 251))
[((297, 52), (406, 52), (496, 142), (496, 251))]
>>> from fontTools.misc.transform import Transform
>>> split_at_extrema((297, 52), (406, 52), (496, 142), (496, 251), Transform().rotate(-27))
[((297.0, 52.0), (84.48072108963274, -212.56513799170233), (15.572491694678519, -361.3686192413668), (15.572491694678547, -445.87035970621713)), ((15.572491694678547, -445.8703597062171), (15.572491694678554, -506.84825401175414), (51.4551516055374, -534.3422304091257), (95.14950889754756, -547.6893014808263))]
"""
# Transform the points for extrema calculation;
# transform is expected to rotate the points by - nib angle.
t2, t3, t4 = transform.transformPoints([pt2, pt3, pt4])
# When pt1 is the current point of the path, it is already transformed, so
# we keep it like it is.
t1 = pt1
(ax, ay), (bx, by), c, d = calcCubicParameters(t1, t2, t3, t4)
ax *= 3.0
ay *= 3.0
bx *= 2.0
by *= 2.0
# vertical
roots = [t for t in solveQuadratic(ay, by, c[1]) if 0 < t < 1]
# horizontal
roots += [t for t in solveQuadratic(ax, bx, c[0]) if 0 < t < 1]
# Use only unique roots and sort them
# They should be unique before, or can a root be duplicated (in h and v?)
roots = sorted(set(roots))
if not roots:
return [(t1, t2, t3, t4)]
return splitCubicAtT(t1, t2, t3, t4, *roots)
def _qCurveToOne_unfinished(self, bcp, point): # XXX need to finish this, for now doing it through a cubic # (BasePen implements _qCurveTo in terms of a cubic) will # have to do. x, y = self.testPoint x1, y1 = self._getCurrentPoint() x2, y2 = bcp x3, y3 = point c = y1 b = (y2 - c) * 2.0 a = y3 - c - b solutions = sorted(solveQuadratic(a, b, c - y)) solutions = [t for t in solutions if ZERO_MINUS_EPSILON <= t <= ONE_PLUS_EPSILON] if not solutions: return
def _qCurveToOne_unfinished(self, bcp, point): # XXX need to finish this, for now doing it through a cubic # (BasePen implements _qCurveTo in terms of a cubic) will # have to do. x, y = self.testPoint x1, y1 = self._getCurrentPoint() x2, y2 = bcp x3, y3 = point c = y1 b = (y2 - c) * 2.0 a = y3 - c - b solutions = sorted(solveQuadratic(a, b, c - y)) solutions = [t for t in solutions if ZERO_MINUS_EPSILON <= t <= ONE_PLUS_EPSILON] if not solutions: return
def qcurveIntersections(x1, y1, x2, y2, *pts):
"""
Computes intersection between a cubic spline and a line segment.
Adapted from: https://www.particleincell.com/2013/cubic-line-intersection/
Takes four defcon points describing curve and four scalars describing line
parameters.
"""
sol = []
# PACK for fontTools
points = []
for pt in pts:
points.append((pt.x, pt.y))
p1 = (pts[0].x, pts[0].y)
for p2, p3 in decomposeQuadraticSegment(points[1:]):
bx, by = (y1 - y2), (x2 - x1)
m = x1 * y2 - x2 * y1
a, b, c = bezierTools.calcQuadraticParameters(p1, p2, p3)
# prepare for next turn
p1 = p3
pc0 = bx * a[0] - by * a[1]
pc1 = (bx * b[0] + by * b[1]) / pc0
pc2 = (bx * c[0] + by * c[1] + m) / pc0
r = bezierTools.solveQuadratic(pc0, pc1, pc2)
for t in r:
if t < 0 or t > 1:
continue
s0 = a[0] * (1 - t) ** 2 + b[0] * 2 * t * (1 - t) + c[0] * t ** 2
s1 = a[1] * (1 - t) ** 2 + b[1] * 2 * t * (1 - t) + c[1] * t ** 2
if (x2 - x1) != 0:
s = (s0 - x1) / (x2 - x1)
else:
s = (s1 - y1) / (y2 - y1)
if s < 0 or s > 1:
continue
sol.append((s0, s1, t))
return sol
def _tValueForPointOnQuadCurve(point, pts, isHorizontal=0):
quadSegments = decomposeQuadraticSegment(pts[1:])
previousOnCurve = pts[0]
solutionsDict = dict()
for index, (pt1, pt2) in enumerate(quadSegments):
a, b, c = bezierTools.calcQuadraticParameters(previousOnCurve, pt1, pt2)
subSolutions = bezierTools.solveQuadratic(a[isHorizontal], b[isHorizontal], c[isHorizontal] - point[isHorizontal])
subSolutions = [t for t in subSolutions if 0 <= t < 1]
for t in subSolutions:
solutionsDict[(t, index)] = _getQuadPoint(t, previousOnCurve, pt1, pt2)
previousOnCurve = pt2
solutions = list(solutionsDict.keys())
if not solutions and not isHorizontal:
return _tValueForPointOnQuadCurve(point, pts, isHorizontal=1)
if len(solutions) > 1:
intersectionLenghts = {}
for t in solutions:
tp = solutionsDict[t]
dist = _distance(tp, point)
intersectionLenghts[dist] = t
minDist = min(intersectionLenghts.keys())
solutions = [intersectionLenghts[minDist]]
return solutions
