[cairo] Struggling with subpixel text (last blocker for 1.8)

Brandon Wright bearoso at gmail.com
Tue Sep 30 20:46:23 PDT 2008

On Tue, Sep 30, 2008 at 3:14 PM, Behdad Esfahbod <behdad at behdad.org> wrote:
> Carl Worth wrote:
>> Meanwhile, I do not think that speculation on the impact of patents is
>> appropriate for the cairo mailing list. But I will say at least this
>> much:
>>> "Hmm, the system FreeType says sub-pixel support isn't legal here, but
>>> we'll provide it anyway because that's how it's always been done."
>> No. The fact that freetype was compiled with its default options in no
>> way suggests that someone has made a ruling about the legality (or
>> illegality) of code that wasn't compiled.
>> A much more likely explanation is that the distributor (Debian, say) of
>> a freetype package, (2.3.7, say), had no idea that there was new code in
>> freetype, (subpixel rendering), not compiled by default. And if
>> applications are using cairo or Xft for that functionality, how would
>> the distributor even know that there's unused and uncompiled code
>> available in the freetype source distribution.
> As a "distributor" let me tell that we're not that clueless.  Because we
> follow upstream projects, and read release notes.  Indeed when FreeType added
> subpixel filtering support, we made sure that it's turned off in Fedora, and
> provided an option for users to enable it via a rebuild if they desire too.
> I'm sure there are quite a few other distributions in the same competency scale.
> behdad
>> -Carl

Carl, I'm certain you're right that no one's intentions for creation
of this patch were legally motivated. But as Behdad points out, some
distributions DO intentionally disable sub-pixel support in FreeType,
and currently still end up with support provided to users courtesy of
Cairo. This is what brings up the legal issue. Your intent in
reverting the new code and trying to come up with a regression-free
approach was to prevent users from losing the sub-pixel support. My
point was that, in most cases, they lose said support because their
packagers tried to disable it in FreeType.

Personally, however, my concerns are primarily the duplication of the
same functionality and, should this code end up back in Cairo, having
two separate code paths. I think it's better to make a clean break
from the old code. That's just my opinion, and you're free to
disregard it completely.


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