| Re: Help ! [message #14903 is a reply to message #10451] |
Thu, 01 April 1999 00:00  |
davidf
Messages: 2866
Registered: September 1996
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Senior Member |
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VU KHAC Tri (tvk@info.fundp.ac.be) writes:
> I write a procedure which reads an image when a button pressed.
>
> pro BTLoad_Event, event
> WIDGET_CONTROL, event.id, GET_UVALUE = info
> fname = DIALOG_PICKFILE(FILE = info.filename, /READ, FILTER = '*.hdr',
> $
> /MUST_EXIST, /FIX_FILTER, PATH = path, /NOCONFIRM)
> IF fname NE "" THEN BEGIN
> Read_Analyze, fname, info.image
> ;^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
> ENDIF
> end
>
> pro Read_Analyze, File, Image
> ;it reads some data from the file and modifies some fields in Image
> end;
>
> I see that in the Read_Analyze, data is read correctly, but in
> BTLoad_Event, info.image is not modified. Anyone can tell me why ?
Because info is a LOCAL variable in this procedure. (You
copied the information in the User Value of the top-level
base into the LOCAL variable info.) If you make changes,
you have to be sure to put it back in the UVALUE before
you exit the event handler:
WIDGET_CONTROL, event.id, SET_UVALUE = info
END;
I still have two cheap IDL Programming books left.
Lot's of information about widget programming there. :-)
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/
Toll-Free IDL Book Orders: 1-888-461-0155
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