def interpolation(v1, v2, t):
    return v1 * (1 - t) + v2 * t

def interpolatePoint(p1,p2,t):
    p1x,p1y = p1.position
    p2x,p2y = p2.position
    return  interpolation(p1x, p2x, t), interpolation(p1y, p2y, t)

def turnLineIntoCubicBez(segment, contour):
    if segment.index == 0:
        prevPoint = contour.points[-1]
    else:
        prevPoint = contour.segments[segment.index - 1].points[-1]
    point = segment.points[-1]
    h1x, h1y = interpolatePoint(prevPoint,point,1/3)
    h2x, h2y = interpolatePoint(prevPoint,point,1-1/3)

    contour.insertPoint(prevPoint.index,(h1x, h1y),type="offcurve")
    contour.insertPoint(prevPoint.index,(h2x, h2y),type="offcurve")

g = CurrentGlyph()
c = g.contours[0]
s = c.segments[0]
turnLineIntoCubicBez(s, c)

It is basically meant to add offcurve points to the line segment, so the segment turns into the curve.
Ofcourse, I got an error an and RF crashes, because the segment of "line" type cannot have offcurve points. What is the best way to achieve this (line turning into the curve) in a proper way?

Best
R

have a look at the Batch extension source code, it has a CompatibleContourPointPen which takes a list of segment types to match.

this seems to work (you’ll need to have the Batch extension installed):

from variableFontGenerator import CompatibleContourPointPen

glyph = CurrentGlyph()

for contour in glyph:
    pointTypes = ['curve' for segment in contour]
    pen = CompatibleContourPointPen(pointTypes)
    contour.drawPoints(pen)
    contour.naked().clear()
    pen.drawPoints(contour.naked())

cheers!

from variableFontGenerator import CompatibleContourPointPen

glyph = CurrentGlyph()

for contour in glyph:
pointTypes = ['curve' for segment in contour]
pen = CompatibleContourPointPen(pointTypes)
contour.drawPoints(pen)
contour.naked().clear()
pen.drawPoints(contour.naked())

Thanks Gustavo!!!
It works like a charm!