Re: gdk double buffering

[Soeren Sandmann <sandmann daimi au dk>]

Patrick <pabos glypsube org> writes:

> graphics programming but my recollection is that back in the DOS days of
> 386 protected mode assembler programming several relatively introductory
> demo tutorials described how to do all drawing in memory and then
> blitting changes to the screen as fast as possible on the refresh
> interrupt (or trying to synchronize with the monitor's refresh signal
> first if no refresh interrupt was available). With x11's asynchronous
> design I could see that exposing the signal to applications could be
> problematic but I would have thought x11 itself would be capable of
> delaying its draws until the refresh signal?

The SYNC extension allows an X client to block the processing of its
request stream until something happens, eg., an vblank interrupt. One
problem is that without kernel support the X server has no way of
knowing when that interrupt happens.

Trying to synchronize with the refresh signal is not really possible
either, because there is no guarantee that the X server is even
scheduled to run at the relevant time.

I have put up the documentation for the SYNC extension here:

        http://www.daimi.au.dk/~sandmann/synclib.PS
        http://www.daimi.au.dk/~sandmann/sync.PS

Søren