0df4997661
It's possible sometimes that 'import cython' does not fail but then 'cython.compiled' raises AttributeError. It actually happened in our internal production environment... Similar issue to https://github.com/pydantic/pydantic/pull/573 and https://github.com/ipython/ipython/issues/13294
516 lines
16 KiB
Python
516 lines
16 KiB
Python
# cython: language_level=3
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# distutils: define_macros=CYTHON_TRACE_NOGIL=1
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# Copyright 2015 Google Inc. All Rights Reserved.
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#
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# Licensed under the Apache License, Version 2.0 (the "License");
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# you may not use this file except in compliance with the License.
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# You may obtain a copy of the License at
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#
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# http://www.apache.org/licenses/LICENSE-2.0
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#
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# Unless required by applicable law or agreed to in writing, software
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# distributed under the License is distributed on an "AS IS" BASIS,
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# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
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# See the License for the specific language governing permissions and
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# limitations under the License.
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try:
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import cython
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COMPILED = cython.compiled
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except (AttributeError, ImportError):
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# if cython not installed, use mock module with no-op decorators and types
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from fontTools.misc import cython
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COMPILED = False
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import math
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from .errors import Error as Cu2QuError, ApproxNotFoundError
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__all__ = ["curve_to_quadratic", "curves_to_quadratic"]
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MAX_N = 100
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NAN = float("NaN")
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@cython.cfunc
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@cython.inline
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@cython.returns(cython.double)
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@cython.locals(v1=cython.complex, v2=cython.complex)
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def dot(v1, v2):
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"""Return the dot product of two vectors.
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Args:
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v1 (complex): First vector.
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v2 (complex): Second vector.
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Returns:
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double: Dot product.
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"""
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return (v1 * v2.conjugate()).real
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@cython.cfunc
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@cython.inline
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@cython.locals(a=cython.complex, b=cython.complex, c=cython.complex, d=cython.complex)
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@cython.locals(
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_1=cython.complex, _2=cython.complex, _3=cython.complex, _4=cython.complex
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)
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def calc_cubic_points(a, b, c, d):
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_1 = d
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_2 = (c / 3.0) + d
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_3 = (b + c) / 3.0 + _2
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_4 = a + d + c + b
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return _1, _2, _3, _4
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@cython.cfunc
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@cython.inline
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@cython.locals(
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p0=cython.complex, p1=cython.complex, p2=cython.complex, p3=cython.complex
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)
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@cython.locals(a=cython.complex, b=cython.complex, c=cython.complex, d=cython.complex)
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def calc_cubic_parameters(p0, p1, p2, p3):
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c = (p1 - p0) * 3.0
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b = (p2 - p1) * 3.0 - c
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d = p0
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a = p3 - d - c - b
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return a, b, c, d
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@cython.cfunc
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@cython.locals(
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p0=cython.complex, p1=cython.complex, p2=cython.complex, p3=cython.complex
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)
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def split_cubic_into_n_iter(p0, p1, p2, p3, n):
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"""Split a cubic Bezier into n equal parts.
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Splits the curve into `n` equal parts by curve time.
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(t=0..1/n, t=1/n..2/n, ...)
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Args:
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p0 (complex): Start point of curve.
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p1 (complex): First handle of curve.
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p2 (complex): Second handle of curve.
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p3 (complex): End point of curve.
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Returns:
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An iterator yielding the control points (four complex values) of the
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subcurves.
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"""
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# Hand-coded special-cases
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if n == 2:
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return iter(split_cubic_into_two(p0, p1, p2, p3))
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if n == 3:
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return iter(split_cubic_into_three(p0, p1, p2, p3))
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if n == 4:
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a, b = split_cubic_into_two(p0, p1, p2, p3)
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return iter(split_cubic_into_two(*a) + split_cubic_into_two(*b))
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if n == 6:
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a, b = split_cubic_into_two(p0, p1, p2, p3)
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return iter(split_cubic_into_three(*a) + split_cubic_into_three(*b))
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return _split_cubic_into_n_gen(p0, p1, p2, p3, n)
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@cython.locals(
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p0=cython.complex,
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p1=cython.complex,
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p2=cython.complex,
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p3=cython.complex,
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n=cython.int,
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)
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@cython.locals(a=cython.complex, b=cython.complex, c=cython.complex, d=cython.complex)
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@cython.locals(
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dt=cython.double, delta_2=cython.double, delta_3=cython.double, i=cython.int
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)
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@cython.locals(
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a1=cython.complex, b1=cython.complex, c1=cython.complex, d1=cython.complex
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)
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def _split_cubic_into_n_gen(p0, p1, p2, p3, n):
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a, b, c, d = calc_cubic_parameters(p0, p1, p2, p3)
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dt = 1 / n
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delta_2 = dt * dt
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delta_3 = dt * delta_2
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for i in range(n):
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t1 = i * dt
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t1_2 = t1 * t1
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# calc new a, b, c and d
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a1 = a * delta_3
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b1 = (3 * a * t1 + b) * delta_2
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c1 = (2 * b * t1 + c + 3 * a * t1_2) * dt
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d1 = a * t1 * t1_2 + b * t1_2 + c * t1 + d
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yield calc_cubic_points(a1, b1, c1, d1)
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@cython.locals(
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p0=cython.complex, p1=cython.complex, p2=cython.complex, p3=cython.complex
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)
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@cython.locals(mid=cython.complex, deriv3=cython.complex)
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def split_cubic_into_two(p0, p1, p2, p3):
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"""Split a cubic Bezier into two equal parts.
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Splits the curve into two equal parts at t = 0.5
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Args:
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p0 (complex): Start point of curve.
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p1 (complex): First handle of curve.
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p2 (complex): Second handle of curve.
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p3 (complex): End point of curve.
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Returns:
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tuple: Two cubic Beziers (each expressed as a tuple of four complex
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values).
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"""
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mid = (p0 + 3 * (p1 + p2) + p3) * 0.125
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deriv3 = (p3 + p2 - p1 - p0) * 0.125
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return (
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(p0, (p0 + p1) * 0.5, mid - deriv3, mid),
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(mid, mid + deriv3, (p2 + p3) * 0.5, p3),
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)
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@cython.locals(
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p0=cython.complex,
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p1=cython.complex,
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p2=cython.complex,
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p3=cython.complex,
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_27=cython.double,
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)
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@cython.locals(
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mid1=cython.complex,
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deriv1=cython.complex,
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mid2=cython.complex,
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deriv2=cython.complex,
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)
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def split_cubic_into_three(p0, p1, p2, p3, _27=1 / 27):
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"""Split a cubic Bezier into three equal parts.
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Splits the curve into three equal parts at t = 1/3 and t = 2/3
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Args:
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p0 (complex): Start point of curve.
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p1 (complex): First handle of curve.
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p2 (complex): Second handle of curve.
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p3 (complex): End point of curve.
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Returns:
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tuple: Three cubic Beziers (each expressed as a tuple of four complex
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values).
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"""
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# we define 1/27 as a keyword argument so that it will be evaluated only
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# once but still in the scope of this function
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mid1 = (8 * p0 + 12 * p1 + 6 * p2 + p3) * _27
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deriv1 = (p3 + 3 * p2 - 4 * p0) * _27
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mid2 = (p0 + 6 * p1 + 12 * p2 + 8 * p3) * _27
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deriv2 = (4 * p3 - 3 * p1 - p0) * _27
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return (
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(p0, (2 * p0 + p1) / 3.0, mid1 - deriv1, mid1),
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(mid1, mid1 + deriv1, mid2 - deriv2, mid2),
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(mid2, mid2 + deriv2, (p2 + 2 * p3) / 3.0, p3),
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)
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@cython.returns(cython.complex)
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@cython.locals(
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t=cython.double,
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p0=cython.complex,
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p1=cython.complex,
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p2=cython.complex,
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p3=cython.complex,
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)
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@cython.locals(_p1=cython.complex, _p2=cython.complex)
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def cubic_approx_control(t, p0, p1, p2, p3):
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"""Approximate a cubic Bezier using a quadratic one.
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Args:
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t (double): Position of control point.
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p0 (complex): Start point of curve.
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p1 (complex): First handle of curve.
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p2 (complex): Second handle of curve.
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p3 (complex): End point of curve.
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Returns:
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complex: Location of candidate control point on quadratic curve.
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"""
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_p1 = p0 + (p1 - p0) * 1.5
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_p2 = p3 + (p2 - p3) * 1.5
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return _p1 + (_p2 - _p1) * t
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@cython.returns(cython.complex)
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@cython.locals(a=cython.complex, b=cython.complex, c=cython.complex, d=cython.complex)
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@cython.locals(ab=cython.complex, cd=cython.complex, p=cython.complex, h=cython.double)
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def calc_intersect(a, b, c, d):
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"""Calculate the intersection of two lines.
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Args:
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a (complex): Start point of first line.
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b (complex): End point of first line.
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c (complex): Start point of second line.
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d (complex): End point of second line.
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Returns:
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complex: Location of intersection if one present, ``complex(NaN,NaN)``
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if no intersection was found.
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"""
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ab = b - a
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cd = d - c
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p = ab * 1j
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try:
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h = dot(p, a - c) / dot(p, cd)
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except ZeroDivisionError:
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return complex(NAN, NAN)
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return c + cd * h
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@cython.cfunc
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@cython.returns(cython.int)
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@cython.locals(
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tolerance=cython.double,
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p0=cython.complex,
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p1=cython.complex,
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p2=cython.complex,
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p3=cython.complex,
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)
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@cython.locals(mid=cython.complex, deriv3=cython.complex)
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def cubic_farthest_fit_inside(p0, p1, p2, p3, tolerance):
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"""Check if a cubic Bezier lies within a given distance of the origin.
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"Origin" means *the* origin (0,0), not the start of the curve. Note that no
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checks are made on the start and end positions of the curve; this function
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only checks the inside of the curve.
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Args:
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p0 (complex): Start point of curve.
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p1 (complex): First handle of curve.
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p2 (complex): Second handle of curve.
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p3 (complex): End point of curve.
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tolerance (double): Distance from origin.
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Returns:
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bool: True if the cubic Bezier ``p`` entirely lies within a distance
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``tolerance`` of the origin, False otherwise.
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"""
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# First check p2 then p1, as p2 has higher error early on.
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if abs(p2) <= tolerance and abs(p1) <= tolerance:
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return True
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# Split.
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mid = (p0 + 3 * (p1 + p2) + p3) * 0.125
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if abs(mid) > tolerance:
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return False
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deriv3 = (p3 + p2 - p1 - p0) * 0.125
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return cubic_farthest_fit_inside(
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p0, (p0 + p1) * 0.5, mid - deriv3, mid, tolerance
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) and cubic_farthest_fit_inside(mid, mid + deriv3, (p2 + p3) * 0.5, p3, tolerance)
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@cython.cfunc
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@cython.locals(tolerance=cython.double, _2_3=cython.double)
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@cython.locals(
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q1=cython.complex,
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c0=cython.complex,
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c1=cython.complex,
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c2=cython.complex,
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c3=cython.complex,
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)
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def cubic_approx_quadratic(cubic, tolerance, _2_3=2 / 3):
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"""Approximate a cubic Bezier with a single quadratic within a given tolerance.
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Args:
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cubic (sequence): Four complex numbers representing control points of
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the cubic Bezier curve.
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tolerance (double): Permitted deviation from the original curve.
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Returns:
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Three complex numbers representing control points of the quadratic
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curve if it fits within the given tolerance, or ``None`` if no suitable
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curve could be calculated.
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"""
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# we define 2/3 as a keyword argument so that it will be evaluated only
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# once but still in the scope of this function
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q1 = calc_intersect(*cubic)
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if math.isnan(q1.imag):
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return None
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c0 = cubic[0]
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c3 = cubic[3]
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c1 = c0 + (q1 - c0) * _2_3
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c2 = c3 + (q1 - c3) * _2_3
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if not cubic_farthest_fit_inside(0, c1 - cubic[1], c2 - cubic[2], 0, tolerance):
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return None
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return c0, q1, c3
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@cython.cfunc
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@cython.locals(n=cython.int, tolerance=cython.double, _2_3=cython.double)
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@cython.locals(i=cython.int)
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@cython.locals(
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c0=cython.complex, c1=cython.complex, c2=cython.complex, c3=cython.complex
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)
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@cython.locals(
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q0=cython.complex,
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q1=cython.complex,
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next_q1=cython.complex,
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q2=cython.complex,
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d1=cython.complex,
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)
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def cubic_approx_spline(cubic, n, tolerance, all_quadratic, _2_3=2 / 3):
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"""Approximate a cubic Bezier curve with a spline of n quadratics.
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Args:
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cubic (sequence): Four complex numbers representing control points of
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the cubic Bezier curve.
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n (int): Number of quadratic Bezier curves in the spline.
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tolerance (double): Permitted deviation from the original curve.
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Returns:
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A list of ``n+2`` complex numbers, representing control points of the
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quadratic spline if it fits within the given tolerance, or ``None`` if
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no suitable spline could be calculated.
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"""
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# we define 2/3 as a keyword argument so that it will be evaluated only
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# once but still in the scope of this function
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if n == 1:
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return cubic_approx_quadratic(cubic, tolerance)
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if n == 2 and all_quadratic == False:
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return cubic
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cubics = split_cubic_into_n_iter(cubic[0], cubic[1], cubic[2], cubic[3], n)
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# calculate the spline of quadratics and check errors at the same time.
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next_cubic = next(cubics)
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next_q1 = cubic_approx_control(0, *next_cubic)
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q2 = cubic[0]
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d1 = 0j
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spline = [cubic[0], next_q1]
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for i in range(1, n + 1):
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# Current cubic to convert
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c0, c1, c2, c3 = next_cubic
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# Current quadratic approximation of current cubic
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q0 = q2
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q1 = next_q1
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if i < n:
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next_cubic = next(cubics)
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next_q1 = cubic_approx_control(i / (n - 1), *next_cubic)
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spline.append(next_q1)
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q2 = (q1 + next_q1) * 0.5
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else:
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q2 = c3
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# End-point deltas
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d0 = d1
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d1 = q2 - c3
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if abs(d1) > tolerance or not cubic_farthest_fit_inside(
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d0, q0 + (q1 - q0) * _2_3 - c1, q2 + (q1 - q2) * _2_3 - c2, d1, tolerance
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):
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return None
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spline.append(cubic[3])
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return spline
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@cython.locals(max_err=cython.double)
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@cython.locals(n=cython.int)
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def curve_to_quadratic(curve, max_err, all_quadratic=True):
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"""Approximate a cubic Bezier curve with a spline of n quadratics.
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Args:
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cubic (sequence): Four 2D tuples representing control points of
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the cubic Bezier curve.
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max_err (double): Permitted deviation from the original curve.
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all_quadratic (bool): If True (default) returned value is a
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quadratic spline. If False, it's either a single quadratic
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curve or a single cubic curve.
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Returns:
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If all_quadratic is True: A list of 2D tuples, representing
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control points of the quadratic spline if it fits within the
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given tolerance, or ``None`` if no suitable spline could be
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calculated.
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If all_quadratic is False: Either a quadratic curve (if length
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of output is 3), or a cubic curve (if length of output is 4).
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"""
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curve = [complex(*p) for p in curve]
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for n in range(1, MAX_N + 1):
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spline = cubic_approx_spline(curve, n, max_err, all_quadratic)
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if spline is not None:
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# done. go home
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return [(s.real, s.imag) for s in spline]
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raise ApproxNotFoundError(curve)
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@cython.locals(l=cython.int, last_i=cython.int, i=cython.int)
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def curves_to_quadratic(curves, max_errors, all_quadratic=True):
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"""Return quadratic Bezier splines approximating the input cubic Beziers.
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Args:
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curves: A sequence of *n* curves, each curve being a sequence of four
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2D tuples.
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max_errors: A sequence of *n* floats representing the maximum permissible
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deviation from each of the cubic Bezier curves.
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all_quadratic (bool): If True (default) returned values are a
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quadratic spline. If False, they are either a single quadratic
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curve or a single cubic curve.
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Example::
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>>> curves_to_quadratic( [
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|
... [ (50,50), (100,100), (150,100), (200,50) ],
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... [ (75,50), (120,100), (150,75), (200,60) ]
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... ], [1,1] )
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|
[[(50.0, 50.0), (75.0, 75.0), (125.0, 91.66666666666666), (175.0, 75.0), (200.0, 50.0)], [(75.0, 50.0), (97.5, 75.0), (135.41666666666666, 82.08333333333333), (175.0, 67.5), (200.0, 60.0)]]
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|
|
|
The returned splines have "implied oncurve points" suitable for use in
|
|
TrueType ``glif`` outlines - i.e. in the first spline returned above,
|
|
the first quadratic segment runs from (50,50) to
|
|
( (75 + 125)/2 , (120 + 91.666..)/2 ) = (100, 83.333...).
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|
|
|
Returns:
|
|
If all_quadratic is True, a list of splines, each spline being a list
|
|
of 2D tuples.
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|
|
|
If all_quadratic is False, a list of curves, each curve being a quadratic
|
|
(length 3), or cubic (length 4).
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|
|
|
Raises:
|
|
fontTools.cu2qu.Errors.ApproxNotFoundError: if no suitable approximation
|
|
can be found for all curves with the given parameters.
|
|
"""
|
|
|
|
curves = [[complex(*p) for p in curve] for curve in curves]
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|
assert len(max_errors) == len(curves)
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|
|
|
l = len(curves)
|
|
splines = [None] * l
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|
last_i = i = 0
|
|
n = 1
|
|
while True:
|
|
spline = cubic_approx_spline(curves[i], n, max_errors[i], all_quadratic)
|
|
if spline is None:
|
|
if n == MAX_N:
|
|
break
|
|
n += 1
|
|
last_i = i
|
|
continue
|
|
splines[i] = spline
|
|
i = (i + 1) % l
|
|
if i == last_i:
|
|
# done. go home
|
|
return [[(s.real, s.imag) for s in spline] for spline in splines]
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|
|
|
raise ApproxNotFoundError(curves)
|