Path: utzoo!utgpu!jarvis.csri.toronto.edu!mailrus!csd4.milw.wisc.edu!bionet!ames!vsi1!daver!athsys!jim
From: jim@athsys.uucp (Jim Becker)
Newsgroups: comp.windows.x
Subject: Re: Xt and applications that do non-window-related processing
Message-ID: <246@tityus.UUCP>
Date: 17 Feb 89 23:23:58 GMT
References: <2696@daisy.UUCP>
Organization: Athena Systems, Inc., Sunnyvale, CA
Lines: 29

From article <2696@daisy.UUCP>, by klee@daisy.UUCP (Ken Lee):
> In article <626@arisia.Xerox.COM> jlevy.pa@xerox.com (Jacob Levy) writes:
>>Suppose I wanted to write an application that sat in an infinite
>>loop and only every so often checked for input from X. It is
>>simple to do this with Xlib, but seems a lot hairier with Xt.
> 

	This is a somewhat related question and possible solution. I
have a couple of programs that give visual update status on the
screen. Most of the time they are snoozing away, waking up every five
seconds or so.  Currently I am doing a sleep() call, then a call to
XPending() to check for recent events. This works, but sometimes there
is a lag of up to five seconds when I just miss Expose or other
events.

	After playing in the X server code, it appears to me that the
application should be able to do a select() call with the desired
timeout value set and the appropriate bit set for the display->fd
socket connection. Then the select() call would sleep until either the
timeout occurred or there was activity from the X server connection.

	This is speculation, as I haven't had a chance to try this
myself. (It also only works on select() oriented systems..) Does this
sound like it would work correctly? Seems like you could also use a
SIGIO handler and a global flag to indicate the presence of XEvents to
be processed.


-Jim Becker	...!sun!athsys!jim