[comp.windows.x] Using backing store from Xt?

raj@ics.uci.edu (Richard A. Johnson) (07/14/89)

Ok, I've "RTFM"ed and "UTS,L"ed and I still don't see any mention of this:

It would be nice to make use of backing store every once in a while.
Especially with programs like xmh and xcalendar.  That way when parts
of them are obscured I wouldn't have to wait for the program to update them.
I've tried this stuff out with other simpler programs like xmille and it
works real well.  S...o

How can I tell programs like xmh to use backing store when creating all
of their widgits?  Furthermore, how could anyone even tell the Xt
library routines to use backing store when creating *any* widget?  I
would have expected something like "XtNbackingstore" but there isn't
anything like that which I can find.  What's the deal?

Richard

swick@ATHENA.MIT.EDU (Ralph R. Swick) (07/14/89)

> How can I tell programs like xmh to use backing store when creating all
> of their widgits?  Furthermore, how could anyone even tell the Xt
> library routines to use backing store when creating *any* widget?  I
> would have expected something like "XtNbackingstore" but there isn't
> anything like that which I can find.  What's the deal?

The deal is that each widget class which believes that backing store
might be useful for it has to add the resource.  (How would you like
your swap space filled up with backing store for Shells, Boxes, Forms,
and Viewports?).  None of the Xaw widgets have such a resource, so
w.r.t. xmh you're out of luck.  It's probably a good idea, though.

keith@EXPO.LCS.MIT.EDU (07/15/89)

> The deal is that each widget class which believes that backing store
> might be useful for it has to add the resource.  (How would you like
> your swap space filled up with backing store for Shells, Boxes, Forms,
> and Viewports?).

The MIT sample server only creates off-screen bitmaps for windows which
are drawn to; Shells, Boxes, Forms and Viewports are never drawn to and
will not get a pixmap.  It isn't free, but it's not as expensive as you
make it out to be.  We frequently use the -wm option to the server which
adds WhenMapped backing store to every window on the screen.

Keith Packard
MIT X Consortium