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

Carl Worth cworth at cworth.org
Tue Sep 30 11:48:29 PDT 2008


On Sun, 2008-09-28 at 18:17 -0500, Brandon Wright wrote:
> David Turner wrote:
> >If you absolutely want to support LCD filtering even if FreeType doesn't,
> >then I really
> >recommend you to simply ignore the FreeType-specific APIs and just
> >re-implement the
> >damn thing in Cairo.
> >
> >then deal with the legal consequences yourselves...
> I agree with the point David makes here. This is subverting the most
> logical place to cut off the filtering for legal ramifications.

I'm sorry Brandon, but that's presuming that the original patch (for
cairo) had "legal ramifications" as its motivation. It did not as I
understood it, (I thought people just wanted the option of different
kinds of filtering).

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.

-Carl




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