53 lines
1.4 KiB
Python
53 lines
1.4 KiB
Python
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"""Calculate the area of a glyph."""
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from fontTools.pens.basePen import BasePen
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__all__ = ["AreaPen"]
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class AreaPen(BasePen):
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def __init__(self, glyphset=None):
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BasePen.__init__(self, glyphset)
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self.value = 0
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def _moveTo(self, p0):
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self._p0 = self._startPoint = p0
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def _lineTo(self, p1):
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x0, y0 = self._p0
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x1, y1 = p1
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self.value -= (x1 - x0) * (y1 + y0) * 0.5
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self._p0 = p1
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def _qCurveToOne(self, p1, p2):
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# https://github.com/Pomax/bezierinfo/issues/44
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p0 = self._p0
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x0, y0 = p0[0], p0[1]
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x1, y1 = p1[0] - x0, p1[1] - y0
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x2, y2 = p2[0] - x0, p2[1] - y0
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self.value -= (x2 * y1 - x1 * y2) / 3
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self._lineTo(p2)
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self._p0 = p2
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def _curveToOne(self, p1, p2, p3):
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# https://github.com/Pomax/bezierinfo/issues/44
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p0 = self._p0
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x0, y0 = p0[0], p0[1]
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x1, y1 = p1[0] - x0, p1[1] - y0
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x2, y2 = p2[0] - x0, p2[1] - y0
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x3, y3 = p3[0] - x0, p3[1] - y0
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self.value -= (x1 * (-y2 - y3) + x2 * (y1 - 2 * y3) + x3 * (y1 + 2 * y2)) * 0.15
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self._lineTo(p3)
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self._p0 = p3
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def _closePath(self):
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self._lineTo(self._startPoint)
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del self._p0, self._startPoint
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def _endPath(self):
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if self._p0 != self._startPoint:
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# Area is not defined for open contours.
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raise NotImplementedError
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del self._p0, self._startPoint
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