On Tuesday 24 September 2002 04:25, Keith Packard wrote:
Around 19 o'clock on Sep 23, Andy Isaacson wrote:
I just plain don't understand why PseudoColor emulation has to be so
expensive. Can't you just do it in the same manner as the ShadowFB
layer, whereby the screen representation is updated only every 10 ms or
whatever?
Yes, that's the usual implementation (although there are others). The
problem is applications expect that updates to the colormap are cheap,
but sending the entire frame buffer over the AGP bus is quite expensive,
as you say, optimizations are possible, but it takes some clever code to
take advantage of any kind of pipelining on the AGP bus while skipping the
large unmodified parts of the screen.
One thought I just had was that Xlib/Xnest style hacks could give every
client a private colormap. This would limit the damage to that clients
windows instead of forcing a scan of the whole screen.
The RandR question remains though -- if this approach is sufficient to
resolve the needs of 80% of the clients, is the ability to swap which
visuals are mapped directly to the hardware interesting enough to spend
significant effort on in the near future? Or should we just leave RandR
as the resize/rotate extension and leave hardware visual swaps for some
future extension if we ever need it ?
Hello Keith,
FWIF: resize is the most needed/requested feature here since laptops
are more and more common. rotate is nice to have. Visual and
depth switching would be helpful in some cases, but unitl it is
be implemented the old hardware will be replaced with new one ;)
Achim
Achim
Keith PackardXFree86 Core TeamHP Cambridge Research Lab
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