[Xorg] PEX and XIE

Egbert Eich eich at pdx.freedesktop.org
Sun Feb 29 13:13:34 PST 2004

Roland Mainz writes:
 > Egbert Eich wrote:
 > >  > Mozilla's Xlib toolkit has support for XIE... and maybe the (default)
 > >  > GTK+ toolkit for Mozilla get it's XIE support back since this gives a
 > >  > huge speedup for image scaling/blending on platforms who still have XIE
 > >  > support available by default (I am looking here at Solaris/Xsun :) ...
 > >  > PEX can (IMO) be removed... but if you remove XIE it would be nice to
 > >  > provide an alternative which supports things like image scaling,
 > >  > rotation and blending (RENDER doesn't count - it's broken by design...
 > >  > ;-/).
 > > 
 > > If it really gives a signifficant speedup this issue
 > > should be reinvestigated. I once was told it was slow.
 > XIE makes image scaling faster in Mozilla's case since FAR LESS data are
 > transferred over the wire. Think about a small 400x300 image scaled up
 > to 800x600. In the case of client-side scaling four times more image
 > bytes are transferred over the wire than pushing the image as-is to the
 > server and let the server scale it.

That's true for a small image of this size. However what about
Images that are far bigger than the available screen size?
You'd only want to transfer a protion of them. 
I admit that this is a corner case, but since somebody once
bragged to me how much better a Windows image viewer can handle
this situation than the X client this person has tried it
may become an issue that still needs to be handled on the
client side.

 > In the case of alpha blending a whole round-trip is saved - and again
 > all the image bytes transferred from server to client (XGetImage()) and
 > back (XPutIMage()) ...


 > > That it is faster on Solaris may be as SUN has enhanced it.
 > I am not sure whether Sun touched the XIE sources for their
 > implementation... I simply guess the issue explained above is enougth to
 > explain the performace enhancement.

Well, maybe not. It was something I've heared.


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