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Re: 24 bit colors in IDL

William Daffer (I suspect) writes:

> The help file says...
> The colormap/visual class combination is chosen when IDL first
> connects with the X Window server. Note that if you connect with the X
> server by creating a window or 
> using the DEVICE keyword to the HELP procedure, 
> ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
> the visual class will be set; it then cannot be changed
> until IDL is restarted. If you wish to use a visual class other than
> the default, be sure to set it with a call to the DEVICE procedure
> before creating windows or otherwise connecting with the X Window
> server.
> I suspect that the same mechanism is used by
> 'device,get_visual_name=name' as is used in help,/device. In order to
> answer the question, a connection is made to the X-server, the die is
> cast, the matter is settled.
> If a connection to the X-server has not been made, I would rather see
> a "don't know" message returned,rather than have IDL decide on the
> visual. At least that way, when some routine started up, I'd know that
> I still have the option of pseudo color or true color available. This
> way, just asking the question decides the answer.

Oh, this is s-o-o-o-o ugly. And news to me too.
This whole business about never being able to set
your visual class after opening a window is extremely

I would say that if you have no graphics windows 
currently open you ought to be able to change your
visual class. After all, PV-Wave can do it. :-)  :-)



David Fanning, Ph.D.
Fanning Software Consulting
Phone: 970-221-0438 E-Mail: davidf@dfanning.com
Coyote's Guide to IDL Progamming: http://www.dfanning.com/
Toll-Free IDL Book Orders: 1-888-461-0155