| Re: Widget Event_Pro question [message #59479 is a reply to message #59478] |
Mon, 31 March 2008 06:45   |
David Fanning
Messages: 11724
Registered: August 2001
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Senior Member |
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Spon writes:
> As part of a little image display programme, I've currently got a draw
> widget:
>
> Display = WIDGET_DRAW(Base, XSIZE = S[0], YSIZE = S[1], $
> /MOTION_EVENTS, EVENT_PRO = 'SLIDESHOWWIDGET_GETVALUES')
>
> And I'd like to add button events to it. I don't want to get rid of
> the motion events though. The easiest way that I can think of adding
> functionality is to (ideally) have two Event_Pro strings, one to be
> run if a motion event is detected, another if a mouse click is
> detected.
>
> Is there a way of doing this?
>
> Or am I just stuck making my SLIDESHOWWIDGET_GETVALUES programme big,
> confusing and unwieldy?
This will depend entirely on what kind of IDL programmer you
are. :-)
You can't have two different event handlers assigned to a
widget at the same time, but there is nothing that prevents
that single event handler from being an event dispatcher.
The event comes in. The event handler figures out what kind
of event it is (e.g., button up, button down, motion,
expose, etc.), and then the event is passed onto some other
IDL procedure or function for further processing. Often,
the info pointer is also needed, along with the event structure,
to completely handle the event.
PRO MyProg_DrawWidgetEventProcessing, event
; Get info pointer.
Widget_Control, event.top, GET_UVALUE=infoPtr
; What kind of event is this?
kind =
['DOWN','UP','MOTION','VIEWPORT','EXPOSE','CH','KEY','WHEEL' ]
CASE kind[event.type] OF
'DOWN': MyProg_HandleButtonDownEvents, event, infoPtr
'UP': MyProg_HandleButtonUpEvents, event, infoPtr
'MOTION': MyProg_HandleButtonMotionEvents, event, infoPtr
ELSE: ; Don't care.
ENDCASE
END
Cheers,
David
--
David Fanning, Ph.D.
Fanning Software Consulting, Inc.
Coyote's Guide to IDL Programming: http://www.dfanning.com/
Sepore ma de ni thui. ("Perhaps thou speakest truth.")
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