<Swing Dev> Updating a JComboBox's values at popup-opening-time

[Clemens Eisserer]

Hello again,

Sorry for wasting your time again :-/

As far as I've seen leouser already submitted tons of patches, and he
even had the same ideas what I've had (simply to re-calculate size
after the PopupListener has been called) and as it seems it turned out
to be not as easy ;)
I did not see many comments regarding problems or critics of the
current patches.

If I would know whats wrong, I could work on improving it.

Thanks for all the time and patience, lg Clemens

2007/8/17, Alexander Potochkin <Alexander.Potochkin at sun.com>:
> Hello Clemens
>
> > Hello again,
> >
> >> It sounds very similar to the bug 4743225
> >> http://bugs.sun.com/bugdatabase/view_bug.do?bug_id=4743225
> >> As far as I know there is no any good workaround for this problem,
> > Oha 68 votes ... thats some kind of funny and sad too. But yes it
> > seems many people are fighting with this problem.
> >
> > I also asked to this list because I would like to fix it, when I asked
> > first I didn't know that there are already some fixes available, but
> > none of them was compatible enough.
> > And regarding to the evaluation-statement well ... now its the perfect
> > time "after mustang" ;)
> >
> > I wonder which type of compatibility problems could arise? Do you
> > think some people depend on the behaviour of the not-resizing list?
> > Is it so risky to simply run the size calculation after the popup
> > listeners (nobody has access to the popup anyway), or do a
> > double-calculation (which would be even save for reflection).
>
> Actually this bug has always been a pain for us
>
> because we didn't find any workaround better than
> showing popup and hiding it again
> which is ugly and cause to popup flickering
>
> combobox is just not ready that its data is changed inside popupListener
>
> you can find my favorite workaround ever in comments for this bug
> http://bugs.sun.com/bugdatabase/view_bug.do?bug_id=4743225
>
> the idea is to open the combobox and close it after that
> with help of awt.Robot
> :-)
>
> By the way if you find a reasonable fix I'll be happy to review it
>
> If you are subscribed to the peabody forum,
> you can also look to the proposed fixes from Brian Harry for this problem
>
> https://jdk-collaboration.dev.java.net/servlets/ProjectForumMessageView?messageID=12475&forumID=1463
>
> Thanks
> alexp
>
>
> > lg Clemens
> >
> >
> >> Actually, there are three options.
> >>
> >> The first is to use reflection on the UI delegate to get the protected popup
> >> field. The second is to wrap the original UI delegate and delegate all the
> >> calls to it. Then, you can override the createPopup method and store the
> >> reference to it in your code.
> >>
> >> Both are very unlikely to break in the future JDK versions since both popup
> >> field and createPopup method are protected and as such are contract between
> >> Swing and third-party LAFs. The first will break under a strict security
> >> manager (JNLP, applets, ...). The second requires much more work to track
> >> LAF changes and delegate all the public and protected methods.
> >>
> >> Yet another option is to call
> >> BasicComboBoxUI.getAccessibleChild() passing 0 as the
> >> second parameter. Here you don't have any guarantees that it won't break
> >> under the future JDK versions, but that would be also highly unlikely.
> >>
> >> Kirill
> >>
> >>
> >> ----- Original Message ----
> >> From: Alexander Potochkin <Alexander.Potochkin at Sun.COM>
> >> To: swing-dev at openjdk.java.net
> >> Sent: Thursday, August 16, 2007 11:16:23 AM
> >> Subject: Re: <Swing Dev> Updating a JComboBox's values at popup-opening-time
> >>
> >> Hello Clemens
> >>
> >> It sounds very similar to the bug 4743225
> >>
> >> http://bugs.sun.com/bugdatabase/view_bug.do?bug_id=4743225
> >>
> >> As far as I know there is no any good workaround for this problem, sorry
> >>
> >> alexp
> >>
> >>
> >>> Hello,
> >>>
> >>> This is both a question and (if its really a problem) maybe an idea
> >>> for enhancement.
> >>>
> >>> I've a JComboBox which should update its values at the time it is
> >>> opened (because the come from a source which changes from time to time
> >>> during the life of the JComboBox and I don't want to update it
> >>> periodically).
> >>> What I did was to register a PopupListener and changed the item of the
> >>> ComboBox but the problem was that the Popup already existed - and
> >>> although its values were updated its size was not.
> >>> If I e.g. had 1 entry before the update and 4 afterwards I got a list
> >>> with the size of 1 entry with very small scrollbars.
> >>>
> >>> The root of the problem seems to be that there is no legal way to
> >>> access the BasicComboPopup (or whatever its called), as far as I've
> >>> seen.
> >>>
> >>> Could my stuff be done in another way which would not cause the
> >>> problems mentioned above? I currently did a hack which calls
> >>> showPopup/hidePopup in the listener so that the too small list is
> >>> hidden and afterwards the larger list appears but thats really a hack.
> >>>
> >>> I wonder wether it would be ok to work on that stuff so that the list
> >>> re-calculates its size also when items are removed/added when the
> >>> popup is already visible? Do you think that could break something?
> >>>
> >>> Please feel free to send commend, I would be really happy about
> >> suggestions.
> >>> lg Clemens
> >>
> >>
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