[HarfBuzz] Unsure how to use HB output to combine characters

[Behdad Esfahbod]

I never heard about Kokonor font before.  According to this Microsoft website:

  http://www.microsoft.com/typography/fonts/macosx.aspx

It's a native Apple font.  In which case I guess it's an AAT font.  You need
to compile HarfBuzz with CoreText shaper enabled for this to work.

behdad

On 14-11-28 02:02 AM, Simon Cozens wrote:
> On 28/11/2014 18:22, Martin Hosken wrote:
>> Is it that the Kokonor font has the diacritics as overstriking, i.e. 
>> with a negative x-min (and probably x-max too)? This would account
>> for all the advance being on the base character and none on the
>> diacritic.
> 
> Huh. Well, in *that* case, Harfbuzz (or possibly FT) is not telling me
> the truth about how to position my glyphs.
> 
>>> What am I doing wrong?
>> Allowing the PDF viewer to do shaping?
> 
> So I *shouldn't* be getting two glyphs out of Harfbuzz. If I run
> hb-shape using the Jomolhari Tibetan font, it gives me one glyph.
> 
> Aha! Looking at the Kokonor font repertoire in Font Book, it *does* have
> the SA/KA combination sitting right there in glyph position 318.
> Harfbuzz should surely be returning that to me. The other Tibetan font
> that comes with OS X, Kailasa, has a SA/KA combination but I still get
> two separate glyphs out of Harfbuzz.
> 
> OS X's own font shaper *can* render Tibetan stacks properly in both
> Kokonor and Kailasa, as the text works fine in the browser / text editor
> / etc. That information must be there in the font to render the stacks
> correctly, but Harfbuzz is not correctly picking it up.
> 
> On the page
> http://digitaltibetan.org/index.php/Tibetan_Fonts#Mac_OS-X_Unicode_fonts
> , it says "Unfortunately both Mac OS-X 10.5 and 10.6 (which supports
> Tibetan) and Adobe's programs support a different set of OpenType
> features which are required to correctly render Tibetan glyphs. So far
> Chris Fynn's Jomolhari ID font is the only publicly available font that
> supports all platforms." Are funny OpenType tables in use?
> 
> I'm shocked; it looks like this might not actually be my fault at all.
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-- 
behdad
http://behdad.org/