>
> > I wrote a plugin to talk to the freetype 2 library
>
> This looks great! Are you going to extend this to subpixel
> anti-aliasing? This would require a per-component alpha mask bitblt
> mode, which would be less efficient, I guess. However, it certainly
> makes quite a difference on LCDs. :-)
>

There is another twist to all of this that accounts for the very high
quality typography now observable on Linux systems (the best in the
world, IMHO).  Keith Packard's code in Xft not only does subpixel decimation
of the RGB components, but he also adjusts the hints to integer pixel
boundaries; the only pixels that end up "fuzzy" in this scheme are those
which would otherwise be jaggy.

I recommend talking a careful look at the Xr/Xc libraries that Carl Worth
and Keith Packard are working on right now; it will do porter/duff image
composited AA graphics with a postscript like API (see http://www.xsvg.org/).
At some point soon, I believe they intend to take the work done in Xft and
have similar text capabilities in Xr/Xc.

Note that these libraries are not X specific, and in fact they are
keeping X out of the API's.  They will render to pixels, or to other
pluggable back ends (e.g. X Render extension, OpenGL,  and potentially
other OS's graphics systems, etc).  This would continue Squeak's
desire to be pixel for pixel compatibile across platforms.

Carl and Keith are writing this up for OLS; you will probably be able
to get a copy of the paper in a few weeks; code is all open source, etc.

And yes, doing alpha compositing is slower than simple bit-blit, but
machines are fast enough these days that most apps find software implementations
adequate: full AA alpha composited text in software on a 1ghz pentium
is around 30K characters/second.  Machines are just so nice and fast these
days... :-).

                             - Jim


--
Jim Gettys
Cambridge Research Laboratory
HP Labs, Hewlett-Packard Company
Jim.Gettys at hp.com