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Re: Exceed and IDL [message #16197 is a reply to message #16191]

Wed, 07 July 1999 00:00

Liam Gumley
Messages: 473
Registered: November 1994

Senior Member

David Fanning wrote:
> Several obtuse reasons for setting RETAIN=0 in a draw widget
> come immediately to mind:
>
> (1) You are using object graphics in the window, in which
> case RETAIN should *always* be set to 0.
>
> (2) You know how screwy colors can be and you wish to
> protect the colors associated with this application
> by "restoring" your colors every time the widget is
> exposed.

David points out some good reasons why an IDL programmer should not
assume a particular value for RETAIN. Here's a few other values/settings
that I've learned not to take for granted when an application runs (i.e.
I don't assume any particular value).

(1) DEVICE keywords:
RETAIN
DECOMPOSED
SET_CHARACTER_SIZE

(2) System variables:
!ORDER (order for displaying images)
!D.TABLE_SIZE (size of the color table)
!D.N_COLORS (number of colors available)
!D.NAME (name of the current display device)
!D.WINDOW (index of the current graphics window)

(3) Widget appearance:
WIDGET_CONTROL keyword DEFAULT_FONT

Anyone else care to add to the list?

Cheers,
Liam.

--
Liam E. Gumley
Space Science and Engineering Center, UW-Madison
http://cimss.ssec.wisc.edu/~gumley

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[Message index]

		Re: Exceed and IDL By: meron on Thu, 08 July 1999 00:00
		Re: Exceed and IDL By: Mark Hadfield on Thu, 08 July 1999 00:00
		Re: Exceed and IDL By: Mark Hadfield on Thu, 08 July 1999 00:00
		Re: Exceed and IDL By: davidf on Wed, 07 July 1999 00:00
		Re: Exceed and IDL By: Richard G. French on Wed, 07 July 1999 00:00
		Re: Exceed and IDL By: Liam Gumley on Wed, 07 July 1999 00:00
		Re: Exceed and IDL By: davidf on Wed, 07 July 1999 00:00
		Re: Exceed and IDL By: bkrrrrr on Wed, 07 July 1999 00:00
		Re: Exceed and IDL By: Liam Gumley on Wed, 07 July 1999 00:00
		Re: Exceed and IDL By: bkrrrrr on Tue, 06 July 1999 00:00
		Re: Exceed and IDL By: Liam Gumley on Tue, 06 July 1999 00:00
		Re: Exceed and IDL By: Liam Gumley on Tue, 06 July 1999 00:00
		Re: Exceed and IDL By: Barry Latter on Tue, 06 July 1999 00:00
		Re: Exceed and IDL By: davidf on Mon, 05 July 1999 00:00

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