[cairo] Text rendering questions

Behdad Esfahbod behdad at behdad.org
Wed Nov 5 18:12:11 PST 2008

Ian Britten wrote:
> Behdad Esfahbod wrote:
>>>>>> What should I expect regarding the specified (FT) font?  Should it
>>>>>> always be used?  When my Regular text is drawn using an Italic
>>>>>> font, or my Bold text is drawn using a Regular font (And it's very
>>>>>> intermittent/inconsistent), I'm left scratching my head...
>>> Any suggestions about how I might proceed (given I know nothing
>>> about the internals of Cairo)?  One difficulty is that I don't
>>> have a consistently-reproducible test case showing the problem,
>>> which will probably make debugging this ... unpleasant  :(
>> That makes it hard. Perhaps in your code, make a printout of all FT_Face's you
>> pass to cairo (the pointer that is), and the cairo_font_face_t you get.  So we
>> can see what cairo's doing.
> I tried that, but it didn't seem to illuminate much (to me)...
> As I'd hope/expect, I got a unique cairo_font_face_t pointer back
> for each call to cairo_ft_font_face_create_for_ft_face(), irregardless
> of whether I was passing in a new/unique FT_Face pointer, or whether
> it was one I had cached.

Without further knowing how you are modifying the FT_Face, I'm out of ideas.

> Is there somewhere in the Cairo code that I could/should look?  I'm
> not familiar with the internals, but I'm guessing I'm not going to
> get to the root of this without rolling up my sleeves...   :(
> I've been grubbing around in cairo-ft-font.c, since that seems to be
> all the FT-specific code.  I'm still going on an assumption that the
> basic Cairo text rendering works correctly, and my problem must be
> related to something I'm doing - With my Cairo/FT interaction being
> the primary suspect...
> Or should I be looking elsewhere (ie: Wherever the surface is finally
> written out?  Or maybe in the PDF code?)?

The PDF, all the font-subset files, ...  You really don't want to dig in there!

Maybe try to reproduce your problem with the image backend?


> As always, may thanks for any help/info/suggestions!
> Ian
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