descent attributes are always multiplied by 2

[tx46]

for prop in ["os2_windescent", "os2_typodescent", "hhea_descent"]:
    adjust(font, prop, args["factor"] * 2)

I don't think this is correct. Either way, I get more consistent and better results when changing it to:

for prop in ["os2_windescent", "os2_typodescent", "hhea_descent"]:
    adjust(font, prop, args["factor"])

Using your absolutely lovely script to patch fonts for Emacs.

[tx46]

Ok, so it's to center lines - I get the idea now. However, it seems the factor becomes incorrect because of it, e.g., 1.2 seems to increase height by 40%.

[tx46]

Using a factor of 1.1:

Changing it to NOT multiply descent by 2:

I think something is wrong with the calculation. I'll look into it.

[tx46]

Alright, this seems to be what you want:

for prop in ["os2_windescent", "os2_typodescent", "hhea_descent"]:
    f = 1 + (args["factor"] - 1) * 2
    adjust(font, prop, f)

I.e., multiply all of factor over 1 with 2. So a factor of 1.3 should not yield 2.6, but rather 1.6 (hence 1 + (f - 1) * 2)

Looks perfect for all factors: