Re: [ROOT] Problem with TCanvas when using KDE 2.1

From: Fons Rademakers (Fons.Rademakers@cern.ch)
Date: Wed Aug 01 2001 - 17:15:15 MEST


Hi Brett,

  due to a bug in the ExecuteEvent() of the TFitPanel and TDrawPanelHist
classes the associated canvas was being put in FeedBackMode, which means
double buffering was turned off and exposure events were not correctly
updating the canvas anymore. This is fixed now in CVS.

Cheers, Fons.



Fons Rademakers wrote:
> 
> Hi Brett,
> 
>   this also fails for me in a pretty spectacular way. I am hunting the problem
> down at the moment. It only happens with the DrawPanel and the FitPanel, not
> with the attribute panels. I'll let you know when it's fixed.
> 
> Cheers, Fons.
> 
> Brett Viren wrote:
> >
> > Fons Rademakers writes:
> >  >   this fix is still in ROOT and I run myself always without backingstore
> >  > and don't see any problems (do you?). Maybe something goes wrong when
> >  > Christian mixes the two versions. Version 3.00/01 still has the expose
> >  > events bug which was only fixed in 3.00/05.
> >
> > I have been using "backingstore" all this time.  I just turned it off
> > and I get similar problems as described by Christian and Andreas.  I
> > am fairly certain that I am not mixing ROOT versions (which is from
> > CVS as of 2 days ago).
> >
> > Besides observing the black and white "trail", I notice that the
> > TCanvas flickers.  I am guessing that ROOT is indeed doing a redraw
> > from a backing pixmap, but that somehow this pattern is getting drawn
> > to the pixmap before being flushed to the screen.
> >
> > It is odd that it works for you.  Maybe "backingstore" is turned on
> > implicitly on your system?  Googling around I found the statement that
> > XFree86 4.0 or higher has the backing store disabled by default, which
> > implies that it is enabled by default in v3.  Do you run XFree86 v3 or
> > v4?
> >
> > -Brett.
> 
> --
> Org:    CERN, European Laboratory for Particle Physics.
> Mail:   1211 Geneve 23, Switzerland
> E-Mail: Fons.Rademakers@cern.ch              Phone: +41 22 7679248
> WWW:    http://root.cern.ch/~rdm/            Fax:   +41 22 7677910

-- 
Org:    CERN, European Laboratory for Particle Physics.
Mail:   1211 Geneve 23, Switzerland
E-Mail: Fons.Rademakers@cern.ch              Phone: +41 22 7679248
WWW:    http://root.cern.ch/~rdm/            Fax:   +41 22 7677910



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