Screen Blanker V1.2

A Screen Saver Program for OS/2


Alan Ballard
February 11, 1990

Notice: Screen Blanker is (c) copyright 1990 Alan
Ballard. It may be used without charge and
may be freely distributed as long as it is
not modified in any way. It may not be sold,
traded, or otherwise disposed of for profit
without permission from the author.


Disclaimer: This program is offered on an "as-is" basis
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without any guarantee as to correct
functioning or fitness for any specific
purpose. The author believes this program to
work as described, but you use the program
entirely at your own risk. The author will
not be responsible for any hardware or
software damage, loss of data, or incidental
or consequential damage that may result from
use of the program, whether or not such use
is in accordance with the instructions.

Purpose: A screen saver is a program which blanks the
screen after a specified period of
inactivity, in order to prevent patterns from
being "burned-in" to the screen.

Hardware and software required:
Screen Blanker Version 1.2 requires OS/2
Version 1.1 or 1.2. It should work with
either Standard Edition or Extended Edition
and with any computer and monitor that are
supported by OS/2.

Installation:
Copy the file SCRNBLNK.EXE to a directory
that is part of your normal OS/2 search path.
\OS2 or \OS2\PBIN are good candidates.

Copy the file SCRNBLNK.DLL to any directory
that is specified in your OS/2 LIBPATH.
\OS2\DLL is normally used for DLL's, but any
other directory in the LIBPATH is OK.

Then, modify your STARTUP.CMD file to
activate Screen Blanker each time you reboot
your system. The command to do this is:
SCRNBLNK /INSTALL










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You may also wish to add an entry for Screen
Blanker to the OS/2 1.1 Start Programs menu
or a (version 1.2) Desktop Manager program
group so you can easily start it at other
times.

Usage: Screen Blanker is normally activated from
your STARTUP.CMD file whenever the system is
booted, as described under Installation
above.

Once Screen Blanker has been activated, it
will monitor keyboard and mouse activity in
all OS/2 sessions. If the specified period
elapses without either being used, the screen
will be blanked. Optionally, a display of the
current date and time will be shown in random
positions on the screen.

The screen can be restored to its previous
state by pressing any key or moving the
mouse. (If this version of Screen Blanker is
used with OS/2 1.1 and the October 1989
release of 1.2, the keyboard must be used to
restore the screen.)

Screen Blanker may also be started at other
times in any of the usual OS/2 ways -- by
selecting it from the File System, by an
entry in a Start Programs menu, or by
entering the command SCRNBLNK from a command-
line window.

When Screen Blanker is started it normally
displays a dialog box that allows you to set
some options. The command line parameter
/INSTALL used at startup suppresses this
dialog box and uses default or previously set
values.

If Screen Blanker is already active when it
is started, the new copy communicates with
the previous copy to change the options in
effect. The Remove button in the dialog box
can be used to terminate a previously-
activated screen blanker.

Screen Blanker will not blank the screen
while the Dos Compatibility mode session is
in control of the screen. A separate Dos
screen blanker may be used in the Dos
compatibility session.

Options The Screen Blanker dialog box allows

selecting the time interval at which blanking
should occur. The default is five minutes.









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The "Show clock" check box can be used to
control whether the time and date are
displayed during "blanked" periods. If "Show
clock" is selected, then the "Colors"
pushbutton can be used to adjust the colors
used in the time/date display. When this
pushbutton is selected a second dialog box
pops up containing scroll bars that are used
to select the colors.

If the "Save settings" check box is selected,
then your preferences for the other options
will be saved in the system OS2.INI file, and
will be applied automatically whenever the
Screen Blanker is subsequently started.

Caveats: (1) Screen Blanker uses the OS/2 VioPopup service
to blank the screen. OS/2 limits use of this
function to one program (session) at a time.
This means that if a running program has
taken over the screen by "popping up",
Screen Blanker will be unable to blank the
screen. It also means that a running program
that wants to use the "popup" while the
screen is blanked will be unable to do so.
Most programs that use this function appear
to wait for the screen to be available, so in
practice this doesn't seem to be a serious
problem.

(2) The initial release of OS/2 version 1.2
contains a bug in VioPopUp which results in a
"Protection Violation" (Message SYS1943) if
the program is removed (by selecting the
Remove option). (This occurs only if it has
blanked the screen one or more times before
being removed). This errors arises a few
seconds after the program has terminated and
appears to be beyond my control. It is
apparently harmless. This problem appears to
be fixed by the February 1990 update to OS/2
1.2.


Author: Alan Ballard,
3452 West 11th Avenue,
Vancouver, Canada, V6R 2J9

Compuserve: 70446,44