Accessing opsz fontVariation

Craig · 22 Sept 2021, 03:09

I can't seem to access differing optical size settings in a variable font. This script, based on the documentation (for wght), nets two identical lines.

size(1000, 500)
# pick a font
font("/Library/Application Support/Adobe/Fonts/FeneonSingleVF.ttf")
# pick a font size
fontSize(200)
# list all axis from the current font
for axis, data in listFontVariations().items():
    print((axis, data))
# pick a variation from the current font
fontVariations(opsz=14)
# draw text!!
text("Hello Q", (100, 100))
# pick a variation from the current font
fontVariations(opsz=66)
# draw text!!
text("Hello Q", (100, 300))

Console correctly reports

('opsz', {'name': 'Optical size', 'minValue': 14.0, 'maxValue': 66.0, 'defaultValue': 66.0})

But the display doesn't show the lines at different optical sizes. Does Drawbot tie opsz to font size, preventing forcing an overriding opsz setting?

gferreira · 24 Sept 2021, 13:04

hello @craig,

it looks like variable optical sizes are selected automatically based on the point size. you can then use scale() to make text bigger or smaller:

ttfPath = 'SourceSerif4Variable-Roman.ttf'
txt = 'Handgloves'

font(ttfPath)
translate(20, 100)

with savedState():
    scale(40)
    fontSize(6)
    text(txt, (0, 0))

translate(0, 300)
with savedState():
    scale(13)
    fontSize(19)
    text(txt, (0, 0))

translate(0, 300)
with savedState():
    scale(4)
    fontSize(72)
    text(txt, (0, 0))

hope this helps! cheers

Craig · 26 Sept 2021, 18:17

Thanks @gferreira !

frederik · 27 Sept 2021, 09:46

cool hack, Gustavo

~~Looking at a way to disable the automatic optical size scaling.~~

frederik · 27 Sept 2021, 10:30

what is your OS version?

this simplified example works... on 10.13

translate(50, 50)

font('SourceSerif4Variable-Roman.ttf')
fontSize(76)
fontVariations(opsz=8)
text("hello world", (0, 0))

fontVariations(opsz=60)
text("hello world", (0, 80))

frederik · 27 Sept 2021, 11:14

works also fine on Big Sur (11.4)

Craig · 4 Oct 2021, 01:37

I'm on Big Sur 11.6.

Seems to work with Source Serif Variable, but not with my own font design. Uh oh. There isn't some signal within the font spec that would allow changing the setting or force the linkage to size, is there? It does seem to be accessing the optical sizes when I set at different sizes, but not accepting direct settings of them.

frederik · 5 Oct 2021, 07:23

mm, strange, could you share your font? (offline only with me or a simplified dummy example)

thanks

Craig · 6 Oct 2021, 04:30

@frederik Happy to, is there a DM function on this board or an email address I should use? Thanks.

frederik · 6 Oct 2021, 07:36

frederik at typemytype.com should do it

Craig · 6 Oct 2021, 22:43

Ah wait, I've found the font file also doesn't work in Axis Praxis, and I think it may be because I started with an opsz scale that went in the wrong direction (I based in on stem thickness which is inverse to point size). I think that may be what's screwing the font up in multiple applications. Will see if that can be fixed.

Craig · 9 Oct 2021, 03:00

Sure enough, that seems to have been the problem. A new font file with internal settings for opsz that increase rather than decrease with point size seems to now respond in Drawbot as expected.