Re: Some perspective from the cheap seats...

On Fri, 21 Mar 2003, Egbert Eich wrote:

> Havoc Pennington writes:
>  > IMHO, one thing X.org should do if it wants to reimagine itself is
>  > expand to include toolkit/desktop level concerns and establish
>  > contacts with toolkit and desktop developers. X should really be
>  > developed to meet the needs of the UI, not the other way around.  That
>  > goes from the top down: user -> apps -> desktop -> toolkit -> X -> OS.
>  > 
> 
> Havoc, 
> 
> I do agree with you. However you most not neglect issues t
> hat are not immediately visible from the UI point of
> view: you have to consider how you can map a funtionality
> you propose onto the HW. 
> 
> In the past this has not always been taken into consideration.
> I hope Mark Vojkovitch will give more details on this but
> to give you two examples:
> 
> * Alpha blended cursors have been added with no consideration 
>   for OpenGL.
> 
> * The RENDER extension is nearly impossible to accelerate fully.
> 
> Egbert.

   The cursor issue was fixed a the last minute, so were some
other problems, but some problems still remain.  In fact, part
of 4.3's delay was due to regressions caused by the RandR 
extension not getting fixed in a timely matter.

  The fact of the matter is that few people realize the implementation
issues involved in some of these features.  End users say
they want a particular feature, but specify things in a way that
is nearly impossible to implement or implement efficiently.

   Things like RandR really require radical driver model modifications
to implement in a non-hackish way.  Implications to OpenGL or Xvideo
still aren't entirely clear.  This can't happen overnight as everything
needs to fit together coherently and this is alot of work, and work
that can't really be done by people who don't have experience in
these areas.  In some cases features were added without sufficient
considerations.  Desktop people pretty much got to pick their dream
interfaces with RENDER but this leaves driver people scratching their
heads as to what they're expected to do about it.  Concerns about
the useability of the current design were expressed by people like
Thomas Roell from XiG and myself.  I suppose someday people will
be complaining that RENDER is too slow and blame the XFree86 project
for this, though it was really the consequence of end users having
too much control.

   Another example.  Initially alpha blended cursors were added 
without considerations to the fact that software sprites aren't
compatible with OpenGL direct rendering.   Workarounds are now
in place, but users will probably complain about the results
(yes, on some hardware the alpha blended cursors disappear when
you run OpenGL).

   If you're not careful here, things may start to resemble a
Dilbert cartoon (imagine Dilbert being asked by marketing to
design the cloak of invisibility).  

   Anyhow, to sumarize.  The requests coming from the desktop
people don't really line up with the way the hardware is heading.
So you either don't get everything you want, or you get it in
software. 


			Mark.