StatisticsPen's slant value

[miguelsousa]

@behdad Is there a relationship between the slant value computed by the StatisticsPen and a glyph's italic angle defined in degrees?

Asking because the slant value of the uppercase i of SourceSans3-It.otf is 0.199695. Using a drawing app I can see that the glyph's italic angle is about 11 degrees.

[behdad]

In [3]: math.tan(math.radians(11))
Out[3]: 0.19438030913771848

In [5]: math.degrees(math.atan(0.199695))
Out[5]: 11.293128399694282

[miguelsousa]

Thank you!