| Re: Widgets and research [message #9259 is a reply to message #9248] |
Sat, 14 June 1997 00:00   |
rivers
Messages: 228
Registered: March 1991
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Senior Member |
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In article <MPG.e0b229eb4d1d1e79896a6@news.frii.com>, davidf@dfanning.com (David Fanning) writes:
> Edward S. Meinel writes:
>
>> On the other hand, I am reluctant to try IDL 5.beta because of all the
>> reports of broken widgets. Do _any_ widgets developed with IDL 4 work
>> under 5.0?
>
> As a matter of fact, *all* of my widgets work under IDL 5.0.
> A few of them don't *look* exactly like they did under IDL 4,
> but the problems are aesthetic rather than functional. So
> far every one of them has worked like I expect it to.
I agree with David. I just finished converting a >3,000 line IDL widget
application to being "object oriented", using IDL Objects (but not Object
Graphics). The widgets worked perfectly under IDL 5.0 (Motif) with exactly the
same layout as 4.0 as far as I can see.
The only code which broke under IDL 5.0 was pickfile(). It used to return
"path+file" when selecting existing files, and only "file_name" when entering
the name of a new file. I think the old behavior was a bug.
IDL Objects really simplify complex widget programs, because so don't have to
create a "state" structure and stick in the uvalue of a top level widget. Just
put the object reference to "self" there instead. This is not entirely
obvious, and the Object manual does not have an example, so here is how I do
it.
;; File example__define.pro
function example::init
base = widget_base(uvalue=self)
self.widgets.base = base
self.widgets.exit = widget_button(base, value='Exit')
widget_control, base, /realize
xmanager, 'example::init', base, event='example_event', /no_block
return, 1
end
pro example_event, event
; Note: The main event handler CANNOT be an object method, since xmanager
; won't know how to call it as such. However, it only needs to be 4 lines
; long: retrieve the object reference and call the object method event
; handler, which will know about the objects data structure.
widget_control, event.top, get_uvalue=object
object->event, event
end
pro example::event, event
; This is the event handler which knows about the object
case event.id of
self.widgets.exit: begin
widget_control, event.top, /destroy
end
else: print, 'Unknown widget event'
endcase
end
pro example__define
widgets={example_widgets, base: 0L, exit: 0L}
data = fltarr(30)
t = {example, widgets: widgets, data: data}
end
____________________________________________________________
Mark Rivers (773) 702-2279 (office)
CARS (773) 702-9951 (secretary)
Univ. of Chicago (773) 702-5454 (FAX)
5640 S. Ellis Ave. (708) 922-0499 (home)
Chicago, IL 60637 rivers@cars.uchicago.edu (e-mail)
or:
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Building 434A (630) 252-0405 (lab)
9700 South Cass Avenue (630) 252-1713 (beamline)
Argonne, IL 60439 (630) 252-0443 (FAX)
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