Re: FVWM: RE: Notification: incoming/977

From: Dan Espen <dane_at_mk.telcordia.com>
Date: Fri, 10 Jan 2003 09:10:02 -0500

Dominik Vogt <fvwm_at_fvwm.org> writes:
> On Thu, Jan 09, 2003 at 06:59:35AM -0800, EXT-Wilson, William A wrote:
> > Dan,
> >
> > Attached is a tarball with a sample program. I have included stripped down
> > versions of the two files which are required and a tc.m which will make it.
> > The g_plot file normally resides in
> > ~/app-defaults/g_plot. The part of the code which I suspect is not working
> > correctly with fvwm is:
> >
> > /*
> > * Turn on backing Store & Save Under
> > */
> > if (strcmp(expose,"SERVER") == 0) {
> > attrib.backing_store = Always;
> > attrib.save_under = True;
> > }
> > else {
> > attrib.backing_store = NotUseful;
> > attrib.save_under = False;
> > }
> > XChangeWindowAttributes(screen[snum].G_plot_disp,screen[snum].G_plot_win,
>
> > CWBackingStore | CWSaveUnder,&attrib);
> >
> > which is in x11_gplot.c. This code (which I don't understand was coded a
> > long time ago for a Sun based sonar system which used a Techsource display
> > VME card. Things have changed over the years and we keep tinkering with th
> e
> > plot package to make it work. Using fvwm delivered with Red Hat 7.2 (maybe
> > 7.3) everything was OK. You could minimize a g_plot window and bring it
> > back and you could cover it up with another window and it would restore.
> > Now, when you bring it back, the covered area is black. The only part that
> > comes back is the border and the window title "Gplot Graphics ...".
> >
> > Any and all suggestions would be appreciated.
>
> Is there any chnace that gplot thinks that backing store is used
> when it sets "attrib.backing_store = Always;"? Can you check if
> gplot checks whether backing store is supported by the X server?
> I have heard something about newer XFree releases no longer
> supporting backing store, but that may not be true.

I have the above code. I'll forward it if requested.

The string "expose" is always "SERVER", so it always turns on
backing store.

In addition, it always calls:

XSetGraphicsExposures(screen[snum].G_plot_disp,
  screen[snum].plot_gc,False);

So it tells the X Server it doesn't want expose events.

And, it has no logic to receive expose events.

I tested the code and the screen comes up white, with no detail.
When I cover and uncover it, it remains white. Perhaps I don't
see any problem because I'm running XFree86 3.3.6.

It does seem to be relying on the X Server to restore the
window content.

-- 
Dan Espen                           E-mail: dane_at_mk.telcordia.com
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Received on Fri Jan 10 2003 - 08:12:32 GMT

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