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areaPen.py: calculate area under quadratic curve directly, using Green theorem

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This commit is contained in:
Cosimo Lupo 2016-06-12 03:14:09 +01:00
parent 5f0e48e649
commit 39f919f1f1
1 changed files with 4 additions and 3 deletions
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7
Lib/fontTools/pens/areaPen.py
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@ -14,9 +14,10 @@ def polygon_area(p0, p1):
def quadratic_curve_area(p0, p1, p2): def quadratic_curve_area(p0, p1, p2):
new_p2 = interpolate(p2, p1, 2.0 / 3) x0, y0 = p0[0], p0[1]
new_p1 = interpolate(p0, p1, 2.0 / 3) x1, y1 = p1[0] - x0, p1[1] - y0
return cubic_curve_area(p0, new_p1, new_p2, p2) x2, y2 = p2[0] - x0, p2[1] - y0
return (x1*y2 - x2*y1) / 3
def cubic_curve_area(p0, p1, p2, p3): def cubic_curve_area(p0, p1, p2, p3):