Source code for fontTools.pens.perimeterPen

# -*- coding: utf-8 -*-
"""Calculate the perimeter of a glyph."""

from fontTools.misc.py23 import *
from fontTools.pens.basePen import BasePen
from fontTools.misc.bezierTools import approximateQuadraticArcLengthC, calcQuadraticArcLengthC, approximateCubicArcLengthC, calcCubicArcLengthC
import math

__all__ = ["PerimeterPen"]

def _distance(p0, p1):
	return math.hypot(p0[0] - p1[0], p0[1] - p1[1])

[docs]class PerimeterPen(BasePen): def __init__(self, glyphset=None, tolerance=0.005): BasePen.__init__(self, glyphset) self.value = 0 self.tolerance = tolerance # Choose which algorithm to use for quadratic and for cubic. # Quadrature is faster but has fixed error characteristic with no strong # error bound. The cutoff points are derived empirically. self._addCubic = self._addCubicQuadrature if tolerance >= 0.0015 else self._addCubicRecursive self._addQuadratic = self._addQuadraticQuadrature if tolerance >= 0.00075 else self._addQuadraticExact def _moveTo(self, p0): self.__startPoint = p0 def _closePath(self): p0 = self._getCurrentPoint() if p0 != self.__startPoint: self._lineTo(self.__startPoint) def _lineTo(self, p1): p0 = self._getCurrentPoint() self.value += _distance(p0, p1) def _addQuadraticExact(self, c0, c1, c2): self.value += calcQuadraticArcLengthC(c0, c1, c2) def _addQuadraticQuadrature(self, c0, c1, c2): self.value += approximateQuadraticArcLengthC(c0, c1, c2) def _qCurveToOne(self, p1, p2): p0 = self._getCurrentPoint() self._addQuadratic(complex(*p0), complex(*p1), complex(*p2)) def _addCubicRecursive(self, c0, c1, c2, c3): self.value += calcCubicArcLengthC(c0, c1, c2, c3, self.tolerance) def _addCubicQuadrature(self, c0, c1, c2, c3): self.value += approximateCubicArcLengthC(c0, c1, c2, c3) def _curveToOne(self, p1, p2, p3): p0 = self._getCurrentPoint() self._addCubic(complex(*p0), complex(*p1), complex(*p2), complex(*p3))