GRASS Users:
We recently observed a problem with GRASS 4.1's XDRIVER (Spring 1993 -
Patch Level #1) as it runs on some of our X11 Servers and but not others.
Hoping that some "nice" GRASS User(s) might be able to provide an
explaination for a problem with failing to repaint displayed images after
being covered partially or fully by another windows. With the binaries
running on a either of our two SUN SPARCstations, the failure to repaint
has been observed on two X-Servers: SunSofts's Interactive UNIX 3.0.1
(X11R4/Motif 1.1.1) and NCD's PC-Xware 1.0 running under Windows 3.1.
Also tried the new Static Version of XDRIVER (September 14, 1993) which is
now availble on CERL's FTP Server and noticed no change.
Repainting is observed on the SPARC's own System Consoles and on a MACX
Server (X11R4) with the GRASS 4.1 Code and on both the Interactive UNIX
and PC-Xware Servers when the same operations are performed under GRASS
4.0 (Summer 1991)! Does this imply a change in XDRIVER's Code between
GRASS 4.0 and 4.1, or some subtle X-Server Configuration differences which
are only showing up with the newer code. Can anyone hazard a guess or
know what differences in X-Servers could produce such differences?
Lawrence Houston,
McGill University.
Lawrence Houston (houston@norton.geog.mcgill.ca) writes on 2 Oct 93:
We recently observed a problem with GRASS 4.1's XDRIVER (Spring 1993 -
Patch Level #1) as it runs on some of our X11 Servers and but not others.
Hoping that some "nice" GRASS User(s) might be able to provide an
explaination for a problem with failing to repaint displayed images after
being covered partially or fully by another windows. With the binaries
as you have deduced, this seems to be a problem with the server
(and not grass). I've personally never noticed this behavior
using Sun or MIT servers.
--Darrell
GrassHoppers:
On Tue, 5 Oct 1993, Darrell McCauley wrote:
Lawrence Houston (houston@norton.geog.mcgill.ca) writes on 2 Oct 93:
>We recently observed a problem with GRASS 4.1's XDRIVER (Spring 1993 -
>Patch Level #1) as it runs on some of our X11 Servers and but not others.
>Hoping that some "nice" GRASS User(s) might be able to provide an
>explaination for a problem with failing to repaint displayed images after
>being covered partially or fully by another windows. With the binaries
as you have deduced, this seems to be a problem with the server
(and not grass). I've personally never noticed this behavior
using Sun or MIT servers.
--Darrell
Well the cause of the failure to "Repaint" following an Expose Event turns
out to be caused by some code in XDRIVER (Serve_Xevent.c) which had been
commented out in the Update #1 Package. This was code XDRIVER uses to
support X11 Servers which do NOT support the Backing Stores, but instead
does its own repainting from a Backup Pixmap. It was Olga Waupotitsch at
CERL who had commented out the code as an experiment to reduce multiple
repainting when serveral Events are received. Taking the Comments out
re-enables repainting for these "dumb" Servers, although a bit slow when
the delays over the net are long!
In addition Martijn van Leusen suggests some X11 Servers can be forced to
support Backing Stores with the "-gs" parameter. I have yet to try that,
but that might be another solution!
Lawrence Houston,
McGill University.