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Merge pull request #3743 from cmyr/bez-split-robustness

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[bezierTools] Improve robustness of curve splitting
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Cosimo Lupo 2025-01-21 13:55:05 +00:00 committed by GitHub
commit e0022ded22
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2 changed files with 14 additions and 1 deletions
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9
Lib/fontTools/misc/bezierTools.py
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@ -631,7 +631,14 @@ def splitCubicAtT(pt1, pt2, pt3, pt4, *ts):
((77.3438, 56.25), (85.9375, 43.75), (93.75, 25), (100, 0)) ((77.3438, 56.25), (85.9375, 43.75), (93.75, 25), (100, 0))
""" """
a, b, c, d = calcCubicParameters(pt1, pt2, pt3, pt4) a, b, c, d = calcCubicParameters(pt1, pt2, pt3, pt4)
return _splitCubicAtT(a, b, c, d, *ts) split = _splitCubicAtT(a, b, c, d, *ts)
# the split impl can introduce floating point errors; we know the first
# segment should always start at pt1 and the last segment should end at pt4,
# so we set those values directly before returning.
split[0] = (pt1, *split[0][1:])
split[-1] = (*split[-1][:-1], pt4)
return split
@cython.locals( @cython.locals(

6
Tests/misc/bezierTools_test.py
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@ -144,6 +144,12 @@ def test_splitCubicAtT():
] ]
def test_splitCubicAtT_robustness():
segment = ((-103, -231), (-61, -240), (-31.009, -245), (6, -245))
(_, tail) = splitCubicAtT(*segment, 0.386637)
assert tail[-1] == segment[-1]
def test_solveCubic(): def test_solveCubic():
assert solveCubic(1, 1, -6, 0) == [-3.0, -0.0, 2.0] assert solveCubic(1, 1, -6, 0) == [-3.0, -0.0, 2.0]
assert solveCubic(-10.0, -9.0, 48.0, -29.0) == [-2.9, 1.0, 1.0] assert solveCubic(-10.0, -9.0, 48.0, -29.0) == [-2.9, 1.0, 1.0]