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

Brandon Wright bearoso at gmail.com
Sun Sep 28 16:17:12 PDT 2008

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
think the odds are slim to none that any sane packager is going to
provide the latest Cairo compiled against such an old FreeType. This
really only leaves the case where FreeType is up-to-date,
intentionally compiled without sub-pixel support, and Cairo is saying,
"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." If
a packager really DOES need to shut off the sub-pixel support
completely, it's now going to need to be worked out of Cairo, too.

I can certainly appreciate what Carl was trying to do with this, but
the ONLY backend involved in this code is the FreeType one, so it's
merely adding another checkpoint to a linear dependency to disable
sub-pixel support. In effect, this is really just saving the effort of
packagers who can't out where or how to enable this support the
"regular" way. They'll figure it out quickly enough, and users will
still have the same features they did before. As for the test--it can
branch on the FT_CONFIG_OPTION_SUBPIXEL_RENDERING macro to determine
whether or not it expects to actually get sub-pixel output.

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