Hhea, win, typo?

[MichelangeloNigra (Michelangelo)]

Hi everyone.

Someone could explain me with proper pictures what really typo, win and hhea values are and how to properly set them? Specifically i didn’t understand why in some font files from different foundries, in custom parameters window there are both “typo”, “win” and “hhea” values. Then, according to the explanation on the glyphs web site (for Microsoft), typoLineGap = winAscent + winDescent – UPM (1000 i suppose), but in some font, i.e. Supria Sans, typoLineGap (100) = winAscent (900) + winDescent (300) – UPM (maybe 1000)= 200. This doesn’t work at all, so it’s obvious that the type designer worked with a different UPM values ( 1100 i suppose). So how UPM value affect the overall design of the font?

Thanks for the cooperation

[mekkablue (Rainer Erich Scheichelbauer)]

@MichelangeloNigra

so it’s obvious that the type designer worked with a different UPM

Not necessarily. Not all MS fonts work that way, especially with some Non-Latin scripts, you will have to adapt some values in order to avoid clipping.

@MichelangeloNigra

So how UPM value affect the overall design of the font?

Changing your UPM value does what it says: different number of units per em, i.e., different apparent scale.