Re: [ft-devel] vertBearingY of CFF glyphs is always unscaled

[Khaled Hosny]

On Thu, Apr 04, 2013 at 06:14:07AM +0200, Werner LEMBERG wrote:
> 
> [CCed Behdad]
> 
> > I had an issue with vertical text layout in HarfBuzz, in short we
> > have the calculation:
> > 
> >     y = metrics.horiBearingY - (-metrics.vertBearingY)
> > 
> > and since horiBearingY is scaled with font size while vertBearingY
> > is not, the result was completely wrong resulting in misplaced
> > glyphs (it was "mysterious because it affected only glyphs where the
> > value of this calculation was used, and the degree of misplacement
> > changes with font size).
> 
> I fear that support for the various vertical metrics components is
> severely broken in FreeType.  In particular, values are computed
> differently for different font formats.  To fix this for all font
> formats it would be necessary to investigate the issue in great
> detail; in particular, we need a detailed comparison with the MS and
> Apple engines: Some comments in FreeType indicate that, for example,
> the OpenType specification and recommendations contradict the actual
> implementation in Windows (and/or OS X).
> 
> Do you have some time to devote to this issue?  Or maybe another
> volunteer?

I fixed my immediate problem by using FT_LOAD_NO_SCALE and then scaling
on my own (since I don't want embedded bitmaps nor hinting anyway).

I'd like to look into vertical typesetting in general in the next
months, but right now I know very little about it to promise anything.

Regards,
Khaled