| Re: ARG! Direct Color problem IDL 5.5/Linux (decomposed doesn't help) [message #29180 is a reply to message #29177] |
Thu, 07 February 2002 09:34   |
David Fanning
Messages: 11724
Registered: August 2001
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Senior Member |
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Jaco van Gorkom (j.c.van.gorkom@fz-juelich.de) writes:
> That is the situation for video hardware which handles 32-bit color.
> In 8-bit color hardware (think government-funded research) there can only
> be 256 different colors on the screen at any one time. So if I ask IDL to
> allocate 256 colors, it uses a private colormap. This causes color flashing
> when moving in or out of plot windows and/or draw widgets. Result: when
> looking at a plot window in the correct colors, the black and gray/white of
> the slider bars appear in some of the first 20 colors of the color map.
> Usually
> black on black. With the mouse on the slider button, the general desktop
> color
> map is active. Ergo I do not see the plot in the color map I am adjusting.
> Or am I missing something?
Oh, I see what you are talking about. Yes, allocating
256 colors on an 8-bit X Windows system will give you
color flashing problems. This is entirely due to the
way X Windows works, and has nothing to do with IDL.
But it *is* a problem, certainly.
> P.S.: I just got this new PC last week. It seems that those cheap
> videocards
> with 1MB memory are no longer made, so now they got me a whopping 32MB.
> I'll have to start writing those 5-6 lines of code soon! xcolors.pro, isn't
> it?
Something like that. :-)
Cheers,
David
--
David W. Fanning, Ph.D.
Fanning Software Consulting
Phone: 970-221-0438, E-mail: david@dfanning.com
Coyote's Guide to IDL Programming: http://www.dfanning.com/
Toll-Free IDL Book Orders: 1-888-461-0155
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