Knowing if an XserverRegion is empty

Keith Packard keithp at
Fri Nov 30 08:28:48 PST 2007

On Fri, 2007-11-30 at 12:00 +0000, iain wrote:

> I've managed to do this by calling XFixesFetchRegion and then checking
> how many rectangles are returned, but is there any great speed penalty
> for calling this function a lot?

Yes, that requires a round-trip to the X server, which is quite slow.
Note that subtracting a region from an empty region is a fast operation,
so unless you have a lot of subtractions you will avoid, it might well
be faster to do that instead of the round trip.

keith.packard at
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