[cairo] Cairo/FreeType integration [Advanced]

Ian Britten britten at caris.com
Thu Oct 9 09:00:07 PDT 2008

Behdad Esfahbod wrote:

>> At the point I'm trying to integrate Cairo into all this, I
>> basically have an FT_Face, an FT_Glyph, (X,Y) position, angle, etc,
>> I'm just not sure if I can make use of all that, with the existing
>> (public) interfaces from Cairo.  For example, when looking at
>> http://www.cairographics.org/manual/cairo-FreeType-Fonts.html, I
>> don't see any way to work with an existing FT_Glyph...
> Cairo's FreeType integration is at the level of FT_Face and glyph indices.  No
> FT_Glyph involved.

Right.  I'm just concerned about a couple of issues, mostly about how
Cairo is obtaining the actual FT_Glyphs

- Are you doing your own lookup/caching?  We already do this (Using
   the FT ImageCache), and I was thinking that it wouldn't be necessary
   for Cairo to do it too (in our case).
   Admittedly, it might just end up being some extra RAM/CPU overhead,
   but I wasn't sure if I could bypass it and patch in at a lower

- How do you obtain the actual FT_Glyph?  I'm concerned that you may
   not be able to get Glyphs for some of our Faces, since we use a
   customized FL_Library that contains extra drivers (To support
   proprietary font formats).
   I'm uncertain if the FT_Face I give you connects back to our
   FT_Library (and driver), or if you'll end up using your own
   instance (without our driver), meaning you'd be unable to get the
   correct FT_Glyph.

Anyways, I'll start by trying to use the existing interfaces, and
see where I get.  I'm only asking about this stuff (Before trying it)
to hopefully avoid wasting my time by heading down the wrong path...

> If you need metrics, use cairo API for that too.

Thanks anyway, but as I mentioned earlier, we already have an
extensive framework built on ICU and FreeType to handle all that.
I only need to push stuff to Cairo - I don't think I need to ask
Cairo for any information.

As always, many thanks for any info, suggestions, etc!

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