new_contents: """Calculate the perimeter of a glyph."""
  
  from __future__ import print_function, division, absolute_import
  from fontTools.misc.py23 import *
  from fontTools.pens.basePen import BasePen
  from fontTools.misc.bezierTools import splitCubicAtT
  import math
  
  
  def distance(p0, p1):
  	return math.hypot(p0[0] - p1[0], p0[1] - p1[1])
  
  
  class PerimeterPen(BasePen):
  
  	def __init__(self, tolerance=0.005, glyphset=None):
  		BasePen.__init__(self, glyphset)
  		self.value = 0
  		self._mult = 1. + tolerance
  
  	def _moveTo(self, p0):
  		pass
  
  	def _lineTo(self, p1):
  		p0 = self._getCurrentPoint()
  		self.value += distance(p0, p1)
  
  	def _addCubic(self, p0, p1, p2, p3):
  		arch = distance(p0, p3)
  		box = distance(p0, p1) + distance(p1, p2) + distance(p2, p3)
  		if arch * self._mult >= box:
  			self.value += (arch + box) * .5
  		else:
  			for c in splitCubicAtT(p0, p1, p2, p3, .5):
  				self._addCubic(*c)
  
  	def _curveToOne(self, p1, p2, p3):
  		p0 = self._getCurrentPoint()
  		self._addCubic(p0, p1, p2, p3)
  
subject: copy PerimeterPen from symfont.py