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