Re: some XFree86 5.0 questions...

Keith Packard wrote:
> Around 14 o'clock on Mar 20, Martijn Sipkema wrote:
>>Will XFree86 5.0 use Xft for font rendering or might
>>it (also) use Sun's STSF (http://stsf.sf.net)?
> 
> 
> You're trying to compare apples with oranges.  Xft is just a new way of
> placing specific glyphs at specific locations on the screen while STSF is a
> whole text layout system that computes the location for the glyphs based on
> complex information available in modern font formats like OpenType's GSUB
> and GPOS tables.

Correct.  STSF offers a superset of the Xft functionality, and it should be
possible, with the changes incorporated in the latest STSF, to write a libXft
implementation that sits on top of STSF.

> STSF is much more comparable with Pango in it's functionality.  These are
> "text layout engines", and only a few of them have been deployed anywhere.
> Because this area of work is so new, I hope we'll see lots of different
> ideas explored so that we can get a sense of what things work best.  It may
> be that in a while we'll all have a general agreement on the basic
> operations of the system and may be able to standardize on a single
> interface, but I think it's imprudent to just pick one now and hope it all
> works out.

There is some experience outside the X world - STSF is based on what we've
learned from experience with Java2D TextLayout and Apple's ATSUI.

> I will say that I hope STSF can take advantage of what we've learned about 
> handling fonts entirely on the client side of the wire.

The STSF & Xst API's are transparent to which side of the wire the fonts are
handled on.  We've developed an Xst implementation that works as an X protocol
extension handling the fonts on the server side, which works well for us, but
we've also got support for handling fonts on the client side as a fallback when
the XST extension is not available in the X server.  Our current experience is
that the server side version offers higher performance and less per-client
overhead.

-- 
	-Alan Coopersmith-      [email protected]
	 Sun Microsystems, Inc.   -   Sun Software Group
	 Quality, Integration, & Customer Success (QICS)
	 Platform Globalization Engin. - X11 Engineering