| Re: Backing store [message #9912 is a reply to message #1022] |
Thu, 11 September 1997 00:00  |
davidf
Messages: 2866
Registered: September 1996
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Senior Member |
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William Thompson is having some problems with backing store
on him Alpha Workstations. He writes:
> It seems to me that there are two possibilities. Either the problem is
> associated with the newer Alpha hardware, or with the newer version of the
> Operating System. So far, we have not upgraded our older machines to OSF 4.0,
> so maybe that's why those machines do not give any problems.
>
> I could put DEVICE, RETAIN=2 into the IDL startup script, but according to the
> online help:
>
> Pixmaps are a precious resource in the X server, so backing
> pixmaps should only be requested for windows with contents
> that must absolutely be preserved.
>
> Has anyone else noticed this behavior under Digital Unix? Is there anything to
> do to tune the system to keep this from happening?
I don't know about Alpha Workstations, but I do know that I
wouldn't put Device, RETAIN=2 into an IDL startup file if you
are planning to run any IDL object graphics programs. These
programs just do not run correctly when the RETAIN flag is set
to 2. On my machine the problem mostly manifests itself by
no object graphics axis annotation when object windows
are resized. If you don't know what the problem is, you spend
a lot of time worrying about whether you are keeping up with
the latest programming techniques. :-(
Object graphics are best done in windows with no backing
store set at all. (Object graphics contain their own means
of providing backing store or window repair, after all.)
What I have been doing is turning off backing store completely
at the system level, and using the Window, RETAIN=2 flag on direct
graphics windows when I create them. This allows me to use
direct graphics and object graphics windows in the same
application without conflicts.
Cheers,
David
--
David Fanning, Ph.D.
Fanning Software Consulting
Customizable IDL Programming Courses
Phone: 970-221-0438 E-Mail: davidf@dfanning.com
Coyote's Guide to IDL Programming: http://www.dfanning.com
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