convert lines to curves

lineToCurvesConverter.py

from fontTools.pens.basePen import BasePen

from lib.tools.bezierTools import calculateAngle

from math import sin, cos, radians

class MyPen(BasePen):
    
    def __init__(self, outpen, distance, insice):
        BasePen.__init__(self, None)
        self.pen = outpen
        
        self.previousPoint = None
        self.firstPoint = None
        
        self.insice = insice
        self.distance = distance
        
    def _moveTo(self, (x, y)):
        print "move", x, y
        self.pen.moveTo((x, y))
        self.previousPoint = x, y
        self.firstPoint = x, y
    
    def _lineTo(self, (x, y)):
        print "line", x, y
        a = calculateAngle(self.previousPoint, (x, y), inDegrees=False)
        
        px, py = self.previousPoint
        
        adjustment = radians(self.insice)
        
        offx1 = px + cos(a-adjustment) * self.distance
        offy1 = py + sin(a-adjustment) * self.distance
        
        offx2 = x - cos(a+adjustment) * self.distance
        offy2 = y - sin(a+adjustment) * self.distance
        
        self.pen.curveTo((offx1, offy1), (offx2, offy2), (x, y))
        self.previousPoint = x, y
    
    def _curveToOne(self, (x1, y1), (x2, y2), (x, y)):
        print "curve", x, y
        self.pen.curveTo((x1, y1), (x2, y2), (x, y))
        self.previousPoint =  x, y
    
    def closePath(self):
        print "closePath"
        if self.firstPoint != self.previousPoint:
            self.lineTo(self.firstPoint)
        self.pen.closePath()
        self.previousPoint = None


g = CurrentGlyph().getLayer("foreground")

layer = g.getLayer("result")
layer.clear()

myPen = MyPen(layer.getPen(), 100, -10)

g.draw(myPen)