Re: [gtk-list] Re: Gdk, X11, and backing store

[Joe Pfeiffer <pfeiffer cs nmsu edu>]

jgarzik@pobox.com writes:
   > For some reason not totally clear to me, it is much faster to use
   > backing store than to do the exposure handling yourself by drawing in
   > a pixmap and just copying it when you get the exposure event. I
   > suspect that the X-server is using video-memory than is not visible on
   > the screen, whereas such memory is not available for a user process,
   > but I might be wrong.

If the server is doing it, there's a whole mess of deciding to send
you an expose, sending it to your client, you picking up the event,
you deciding to copy the pixmap, you sending a message back, and the
server processing the message that is bypassed.

   I believe that the X server uses server-side resources for the backing
   store, as you suspect.  If you want to do your own backing store-type
   functionality, use XImage*() calls.  An XImage is a server-side
   resource, whereas (IIRC) a pixmap is a client-side resource.

Backwards -- an XImage is client-side (it lives in your program), a
Pixmap is server-side (it lives in the server).  I haven't gotten as
far as exploring gdk yet, but if you have to do your own backing store
a pixmap is the way to do it.

   Server-side versus client-side makes a world of difference in many
   situations, especially when running X over a network.

Yep.
-- 
Joseph J. Pfeiffer, Jr., Ph.D.       Phone -- (505) 646-1605
Department of Computer Science       FAX   -- (505) 646-1002
New Mexico State University          http://www.cs.nmsu.edu/~pfeiffer