[HarfBuzz] inputting text already containing some glpyhs

[Khaled Hosny]

I was thinking about adding HB support to FontForge's "metrics" view,
which input can as well be a mix of characters and glyph indices, but I
did no actual work so far.

I was wondering if hb_shape() accepts a buffer that contains glyphs
indices? if it is true, may be one can first convert characters to
corresponding "base" glyph indices using some FT function (or something
like Cairo's "toy" text API) and then pass the "pure" glyph indices
buffer to HB, any ideas?

Regards,
 Khaled

On Thu, Apr 21, 2011 at 04:57:35PM -0400, Behdad Esfahbod wrote:
> Hi Eric,
> 
> I understand your request, but I don't think we want to handle that.  The way
> such a case would work, IMO, is that the higher level will break the text into
> text and glyph-index segments, and only pass the text runs to the shaper.
> Shaping glyph indices makes little sense.
> 
> behdad
> 
> On 04/21/11 16:51, Eric Wasylishen wrote:
> > Hi,
> > I have a use case where I want to shape some text which might contain a mix of glyph indices and unicode characters. For example, a string like "hello <glyph 123> world". 
> > 
> > I get the feeling that just having strings like this is discouraged. There are, however, files in the wild that do this (e.g. Apple RTF files will sometime contain glyph indices).
> > 
> > What would you think about allowing a Harfbuzz user preparing their buffer to call hb_buffer_add_glyph with a mask to indicate that the glyph being inserted is already a glyph index?  It looks like the first few phases of hb_ot_shape_execute_internal, up to when hb_substitute_default is called, would have to check for this mask and ignore the glyph or treat it as some placeholder unicode character.
> > 
> > Cheers,
> > Eric
> > 
> > P.S. I'm looking at adding Harfbuzz support to GNUstep, which is where this problem comes up.
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-- 
 Khaled Hosny
 Egyptian
 Arab