/usr/lib/python3/dist-packages/fontTools/pens/statisticsPen.py is in python3-fonttools 3.21.2-1.
This file is owned by root:root, with mode 0o644.
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1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60 61 62 63 64 65 66 67 68 69 70 71 72 73 74 75 76 77 78 79 80 81 82 83 84 85 86 87 88 89 90 91 92 93 94 95 96 97 98 99 100 101 102 | """Pen calculating area, center of mass, variance and standard-deviation,
covariance and correlation, and slant, of glyph shapes."""
from __future__ import print_function, division, absolute_import
from fontTools.misc.py23 import *
import math
from fontTools.pens.momentsPen import MomentsPen
__all__ = ["StatisticsPen"]
class StatisticsPen(MomentsPen):
"""Pen calculating area, center of mass, variance and
standard-deviation, covariance and correlation, and slant,
of glyph shapes.
Note that all the calculated values are 'signed'. Ie. if the
glyph shape is self-intersecting, the values are not correct
(but well-defined). As such, area will be negative if contour
directions are clockwise. Moreover, variance might be negative
if the shapes are self-intersecting in certain ways."""
def __init__(self, glyphset=None):
MomentsPen.__init__(self, glyphset=glyphset)
self.__zero()
def _closePath(self):
MomentsPen._closePath(self)
self.__update()
def __zero(self):
self.meanX = 0
self.meanY = 0
self.varianceX = 0
self.varianceY = 0
self.stddevX = 0
self.stddevY = 0
self.covariance = 0
self.correlation = 0
self.slant = 0
def __update(self):
area = self.area
if not area:
self.__zero()
return
# Center of mass
# https://en.wikipedia.org/wiki/Center_of_mass#A_continuous_volume
self.meanX = meanX = self.momentX / area
self.meanY = meanY = self.momentY / area
# Var(X) = E[X^2] - E[X]^2
self.varianceX = varianceX = self.momentXX / area - meanX**2
self.varianceY = varianceY = self.momentYY / area - meanY**2
self.stddevX = stddevX = math.copysign(abs(varianceX)**.5, varianceX)
self.stddevY = stddevY = math.copysign(abs(varianceY)**.5, varianceY)
# Covariance(X,Y) = ( E[X.Y] - E[X]E[Y] )
self.covariance = covariance = self.momentXY / area - meanX*meanY
# Correlation(X,Y) = Covariance(X,Y) / ( stddev(X) * stddev(Y) )
# https://en.wikipedia.org/wiki/Pearson_product-moment_correlation_coefficient
correlation = covariance / (stddevX * stddevY)
self.correlation = correlation if abs(correlation) > 1e-3 else 0
slant = covariance / varianceY
self.slant = slant if abs(slant) > 1e-3 else 0
def _test(glyphset, upem, glyphs):
from fontTools.pens.transformPen import TransformPen
from fontTools.misc.transform import Scale
print('upem', upem)
for glyph_name in glyphs:
print()
print("glyph:", glyph_name)
glyph = glyphset[glyph_name]
pen = StatisticsPen(glyphset=glyphset)
transformer = TransformPen(pen, Scale(1./upem))
glyph.draw(transformer)
for item in ['area', 'momentX', 'momentY', 'momentXX', 'momentYY', 'momentXY', 'meanX', 'meanY', 'varianceX', 'varianceY', 'stddevX', 'stddevY', 'covariance', 'correlation', 'slant']:
if item[0] == '_': continue
print ("%s: %g" % (item, getattr(pen, item)))
def main(args):
if not args:
return
filename, glyphs = args[0], args[1:]
if not glyphs:
glyphs = ['e', 'o', 'I', 'slash', 'E', 'zero', 'eight', 'minus', 'equal']
from fontTools.ttLib import TTFont
font = TTFont(filename)
_test(font.getGlyphSet(), font['head'].unitsPerEm, glyphs)
if __name__ == '__main__':
import sys
main(sys.argv[1:])
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