Re: PickData Method on IDLgrWindow Object

[davidf(at)dfanning.com (David Fanning)]

Michael Plonski (mplonski@aer.com) writes:

> A while back, I was having a lot of difficulty understanding pickdata
> and select, since pickdata appeared to ignore the object (model) that
> you pass it.  I didn't save the full thread of discussion with RSI but
> the key concept that was throwing me (quoted from the RSI response) was:
> 
> "It is true that PickData DOES NOT check to see if the x,y is within the
> specified object.  But that is precisely what Select is for."

Thank you, Mike, for this timely article.

Just the other day I was modifying my XImage program to show
folks how you could use the Pickdata function to select
an image value from the image object. (The updated program is on
my web page.) I got the program to work fairly quickly, but I
couldn't for the life of me figure out WHY it was working!

I would encourage everyone to save this article, because I'm
pretty sure you would have to be clairvoyant to capture this
information from the IDL documentation. In fact, the documentation
would lead you, probably, in exactly the opposite direction. :-(

Cheers,

David
-- 
David Fanning, Ph.D.
Fanning Software Consulting
Phone: 970-221-0438 E-Mail: davidf@dfanning.com
Coyote's Guide to IDL Programming: http://www.dfanning.com/
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