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items: Re: XLoadCT in a procedure ?????

Re: XLoadCT in a procedure ?????
type: item
description: jgm@nntp.unsw.EDU.AU (Julian Marshall) wrote: > Hi. > I have a slight problem with Xloadct. It does not behave well > when used inside a case statement in a procedure. When Xloadct > is in a procedure, the pro naturally waits for xloadct to be > finished before continuing, but when I use Xloadct within a > case statement, the event handler does not seem to wait for > the Xloadct pro to finish. > > The relevant part of my code is: > > PRO jv_event, event > Widget_control, event.id, GET_Uvalue=eventval > CASE eventval of > > 'COLOUR':Begin > XLoadCT > TvLCT, r1,g1,b1,/GET > XLoadCT > TvLCT, r2,g2,b2,/GET > Combine_CT ;calls another procedure > END > ENDCASE > END > The problem is that XLoadCT is like most widget applications, it uses the Xmanager to handle its events. If you use XLoadCT in a situation in which the XManager has not already been initiated, then it doesn't return until the widget is destroyed causing the XManager's loop to exit. In the above situation, you are calling XLoadCt from within the event handler of a widget application. XLoadCt is simply registered as another widget to be managed by the XManager and because this isn't the first time XManager was called, Xmanager returns and therefore XLoadCt also returns. There are probably numerous ways to get around this problem, but I'm going to give you a quick hack: Copy off the XLoadCT procedure from the IDL distribution library. You may want to rename it so that you don't get the two confused. Then edit your personal version of XLoadCt to change the following line from: XManager, "xloadct", base, GROUP_LEADER = GROUP to: XManager, "xloadct", base, GROUP_LEADER = GROUP, /MODAL It would be nice if XLoadCt came with a modal keyword, but it doesn't. You could go a little further than the above solution and add a MODAL keyword to your version of XLoadCt. This would have the advantage that XLoadCt would work normally unless you wanted it to be a modal dialog box. I hope this helps. Ken Knighton knighton@gav.ga…
creator: Ken Knighton
date: 1995-11-17T08:00:00-00:00

Re: XLoadCT in a procedure ?????
type: item
description: In article <48esa3$8a3@mirv.unsw.edu.au>, jgm@nntp.unsw.EDU.AU (Julian Marshall) writes: > Hi. > I have a slight problem with Xloadct. It does not behave well > when used inside a case statement in a procedure. When Xloadct > is in a procedure, the pro naturally waits for xloadct to be > finished before continuing, but when I use Xloadct within a > case statement, the event handler does not seem to wait for > the Xloadct pro to finish. I don't believe that your statement "When Xloadct is in a procedure, the pro naturally waits for xloadct to be finished before continuing" is correct. XloadXT creates its widgets and then just registers itself with Xmanager, and immediately returns. In many applications this is the way one wants it to work. Pressing the "Change Color" button on an application pops up XloadCT, which then stays around, allowing the use to change colors whenver they want, i.e. they don't have to press "Change Color" again. There is probably a way to get the behavior you want, i.e. the program waits until the user exits XloadCT, perhaps by making a "modal widget" which calls XloadCT. ____________________________________________________________ Mark Rivers (312) 702-2279 (office) CARS (312) 702-9951 (secretary) Univ. of Chicago (312) 702-5454 (FAX) 5640 S. Ellis Ave. (708) 922-0499 (home) Chicago, IL 60637 rivers@cars3.uchicago.edu (Internet)
creator: rivers
date: 1995-11-17T08:00:00-00:00