Re: [gtk-list] Re: GTK or Qt

[Valdis Kletnieks vt edu]

On Tue, 07 Sep 1999 15:57:24 +0200, Jan Van Eetvelde <Jan.VanEetvelde@rug.ac.be>  said:
> we, a group of studens, are making a device for measurments for our
> thesis. I have to write the GUI of this device, ...
> We will use RTLinux to get the data in our computer (Real Time) ... 
> the problem I have, is how to display these data on our screen ? One
> will understand that the refreshing rate has to be as high as possible

Hmm.. Been there, done that.  One of my jobs is to admin a very large SGI
system used for virtual reality work.  A major clue that I can give to you
is to decouple the *getting* of the data from *displaying* the data.

Use 2 processes and shared memory, or 2 threads, or whatever you want.
That way, you can have *ONE* thread doing 100 measurements/second, and
the other thread updating the display 10x/second.  Remember that your
*MONITOR* probably is scanning at 72 or so hz, so updating faster than
that does NO GOOD.  Remember that (at least in the US) TV is 30 frames/sec,
and movies are 24/sec.  You probably don't need to update faster than
that, unless you're trying to do real-time VR immersion or similar tasks,
in which case you have BIGGER problems than picking a toolkit. ;)

I think you'll find that if you're updating a traditional GUI with meters,
buttons, sliders, and the like, that updating more than 10/sec will *annoy*
the users no end.  "Damn, I wish that thing would hold STILL so I can get
a good look at it" ;)

-- 
				Valdis Kletnieks
				Computer Systems Senior Engineer
				Virginia Tech

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