| Re: Returning result from a widget program. [message #12202 is a reply to message #12187] |
Thu, 09 July 1998 00:00  |
David Foster
Messages: 341
Registered: January 1996
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Senior Member |
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Imanol Echave wrote:
>
> Hi people:
>
> I'm writting an IDL function that works with widgets. The user calls an IDL
> function that shows an widget interface to input data. When the user pushes the
> "OK" button the function has to return a result that depends on the input data.
> My problem is where to store this result to return it. I can't use the UVALUE of
> the widgets because when I want to return the result the widgets are destroyed.
> Any advice?
Hi Imanol -
I think the best thing you can do is to first create a "state info"
structure that contains contains useful information about your
widget, including status and especially the "result" from your
user input. Then create a pointer to this structure:
statePtr = ptr_new( { status: 0, status_msg: '', result: 0 } )
Then store this pointer in the UVALUE of the TLB (top-level-base) of
your widget heirarchy, right before calling XMANAGER:
widget_control, base, set_uvalue=statePtr
XMANAGER, 'name', base
(Be SURE not to use /NO_BLOCK here! You want the function to wait
until you're done.)
Then at the beginning of your event handler you get this pointer
back from the UVALUE:
widget_control, event.top, get_uvalue=statePtr
and you can access all of your structure elements within the event
handler like:
temp = (*statePtr).result
Then, at the end of your function, to return the result(s) of the
function you add the next lines *after* the XMANAGER call:
return_value = (*statePtr).result
ptr_free, statePtr ; Be SURE to free memory!
return, return_value
END
Of course, if you need to return more items, you can make a new
structure from some of the fields of (*statePtr), and then return
that instead. The point is that you can use this method to return
whatever you like. The key is that I'm assuming that this will be
a "modal" widget, which will wait until the user presses "Ok"
before returning (keyword /NO_BLOCK is not used in XMANAGER call).
Hope this helps.
Dave
--
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ ~~~~~~
David S. Foster Univ. of California, San Diego
Programmer/Analyst Brain Image Analysis Laboratory
foster@bial1.ucsd.edu Department of Psychiatry
(619) 622-5892 8950 Via La Jolla Drive, Suite 2240
La Jolla, CA 92037
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ ~~~~~~
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