> On Jan 26, 2026, at 10:13 AM, Martin Ruckert <[email protected]> wrote:
>
> Hi all!
>
> This is a bit of a technical question:
>
> I use the function hb_ot_layout_get_size_params() to get the design size
> of an OpenType font. The result specifies a design size in 1/10 of a point.
> So, a design size of 100 means 10pt. OpenType/Harfbuzz assumes that 72 pt = 1
> inch.
> TeX on the other hand assumes that 72.27 pt = 1 inch. So, to convert a design
> size of 100 found for an OpenType font to TeX's points, I should
> divide by 10 and then by 72 (giving the design size in inch)
> and then multiply by 72.27 to get TeX points.
> When I use this formula in HiTeX, my fonts are slightly larger than in XeTeX
> and so are inter-word-spaces and inter-line-skips.
> If I do not use the extra divide and multiply, my fonts are still not the
> same size as those produced by XeTeX.
>
> So how does XeTeX compute the design size of an OpenType font?
>
> Regards
> Martin
>
> --
> Martin Ruckert
> Hochschule München
> Fakultät für Informatik und Mathematik
>
Howdy,
TeX understands Big Points (bp) as a unit.
Good Luck,
Herb Schulz
[email protected]
