[luatex] bug in RTL typesetting?

[Khaled Hosny]

On Mon, Mar 30, 2009 at 02:09:50AM +0200, Khaled Hosny wrote:
> On Mon, Mar 30, 2009 at 12:24:44AM +0200, Hartmut Henkel wrote:
> > On Sun, 29 Mar 2009, Khaled Hosny wrote:
> > nice example! However i don't know what to do in the TLB case. Currently
> > the glyphs hang down from the text baseline (as shown in the example),
> > but maybe in TLB mode also the glyph baselines should be aligned with
> > the text baseline. Any idea what's right?
> 
> I didn't think in it before, I don't know where TLB would be used. Now,
> I can think it is used in Indic scripts (in which the glyphs usually
> hang from the base line), then TRT for Arabic would be the logical
> choice, imagine Devanagari mixed with Arabic. TRB wouldn't make any
> sense for Arabic since it will break the way glyphs are connected
> together, unless the glyphs are rotated 180 degrees which would be very
> funny but almost useless.

I see now, I should have checked it first, sorry. I think in TLB the base
line should be raised to get better matching with, say, Arabic or Latin
script. [1] shows a nice summery of different baselines.

OpenType fonts should provide such information, see [2], so, I think
baseline adjustment should be done as part of OpenType processing.

[1]http://fontforge.sourceforge.net/overview.html#Baseline
[2]http://www.microsoft.com/typography/otspec/BASE.htm

Regards,
 Khaled


-- 
 Khaled Hosny
 Arabic localiser and member of Arabeyes.org team
 Free font developer
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