[HarfBuzz] Units of members of hb_glyph_position_t
eliz at gnu.org
Tue May 28 02:48:08 UTC 2019
> From: Behdad Esfahbod <behdad at behdad.org>
> Date: Mon, 27 May 2019 21:21:10 -0400
> Cc: "harfbuzz at lists.freedesktop.org" <harfbuzz at lists.freedesktop.org>
> control those units (if they are under the client program's control).
> They are controlled mainly using hb_font_set_scale().
What happens if hb_font_set_scale is not called? Is there some kind
> In particular, I get a huge value of x_advance for the letter U+05EA
> HEBREW LETTER TAV when it is followed by U+05BB HEBREW POINT QUBUTS.
> The value of x_advance I get is 1229, which is too large even after
> dividing by 64 (which, btw, I still am not sure is TRT in my case,
> FreeType works in 26.6 fixed-point, ie. 64 units per 1.0. That's where the 64 value comes from. And you
> don't see it in your code because hb_ft_font_create* sets that on hb_font for you.
hb_ft_font_create is not used in the Windows code, because the Windows
code doesn't use Freetype to open and otherwise manipulate fonts.
> In your Windows code, you should call hb_font_set_scale(). I believe right now you are *not* calling, and you
> get values in the face's UPEM. That's the default scale for fonts. You can get the face UPEM using
OK, thanks, I will look into this.
More information about the HarfBuzz