| Re: Porting IDL [message #12493] |
Thu, 13 August 1998 00:00  |
davidf
Messages: 2866
Registered: September 1996
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Senior Member |
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Rose (rmlongfield@my-dejanews.com) writes:
> Hi All (and David Fanning in particular), Sorry Dave, I just happened
> to have a problem with your PROCESS.PRO procedure. :o I used it quickly (on
> my SGI) to produce a *.gif of an image. When I did a view of the *.gif file
> (using xv) , however, I got a black box where the drop down menu is located.
> I've never made a gif file with IDL yet but this is really strange. Does
> anyone else have this experience or is it just another SGI problem?...sigh.
Sigh...
I've found over the years that the best way to find bugs
in your programs is to make a public announcement that they
work. :-(
I can believe that this behavior is happening because the
PROCESS program takes a screen dump of the graphics window
(TVRD) to generate the GIF file. On some workstations this
can be problematic. David Foster has some code called
Safe_TVRD (or something like it) that always does a TVRD
from a pixmap, which is more reliable. I usually like to
do a TVRD from the Z-buffer if I can, because then I
can have access to all 256 colors if I need them.
Unfortunately, adding a lot of convoluted code to
example programs tends to confuse issues rather than
clarify them, so sometimes I opt for the simple solution
that works most of the time instead of the complicated
solution that works all of the time. This makes the
programs easier to follow and still leaves me some
material to put in my book. :-)
The PROCESS program could be improved by adding a
pixmap window and doing the TVRD from that. Then it
really WOULD work the same on PCs and SGI workstations.
As Liam Gumley mentioned yesterday, however, despite my
flippant remarks about "well-written" programs, you have
to test, test, test.
Cheers,
David
--
David Fanning, Ph.D.
Fanning Software Consulting
E-Mail: davidf@dfanning.com
Phone: 970-221-0438, Toll Free Book Orders: 1-888-461-0155
Coyote's Guide to IDL Programming: http://www.dfanning.com/
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