diff --git a/Lib/fontTools/pens/areaPen.py b/Lib/fontTools/pens/areaPen.py new file mode 100644 index 000000000..310a12024 --- /dev/null +++ b/Lib/fontTools/pens/areaPen.py @@ -0,0 +1,57 @@ +"""Calculate the area of a glyph.""" + +import math +from fontTools.pens.basePen import BasePen +from collections import namedtuple + + +P = namedtuple('P', ('x', 'y')) + + +def distance(p0, p1): + return math.hypot(p0.x - p1.x, p0.y - p1.y) + + +def interpolate(p0, p1, t): + return P(p0.x * (1 - t) + p1.x * t, p0.y * (1 - t) + p1.y * t) + + +def polygon_area(p0, p1): + return (p1.x - p0.x) * (p1.y + p0.y) * 0.5 + + +def quadratic_curve_area(p0, p1, p2): + new_p2 = interpolate(p2, p1, 2.0 / 3) + new_p1 = interpolate(p0, p1, 2.0 / 3) + return cubic_curve_area(p0, new_p1, new_p2, p2) + + +def cubic_curve_area(p0, p1, p2, p3): + x0, y0 = p0.x, p0.y + x1, y1 = p1.x - x0, p1.y - y0 + x2, y2 = p2.x - x0, p2.y - y0 + x3, y3 = p3.x - x0, p3.y - y0 + return ( + x1 * ( - y2 - y3) + + x2 * (y1 - 2*y3) + + x3 * (y1 + 2*y2 ) + ) * 0.15 + + +class AreaPen(BasePen): + + def __init__(self, glyphset): + BasePen.__init__(self, glyphset) + self.value = 0 + + def _moveTo(self, p0): + pass + + def _lineTo(self, p1): + p0 = self._getCurrentPoint() + self.value += polygon_area(P(*p0), P(*p1)) + + def _curveToOne(self, p1, p2, p3): + p0 = self._getCurrentPoint() + self.value += cubic_curve_area(P(*p0), P(*p1), P(*p2), P(*p3)) + self.value += polygon_area(P(*p0), P(*p3))