The Original Shareware 1.1/The Original Shareware (WeMake CDs)(Volume 1.1)(CDs, Inc)(1993).iso/10/grabber.zip/GRABBER.DOC

Text File | 1987-05-28 | 9KB | 212 lines

                     GRABBER.COM  Ver. 2.10
                     ----------------------
                   The Screen-Capture Program
                      for the IBM PC/XT/AT
                   and Color/Graphics Adapter



                DOCUMENTATION AND TECHNICAL NOTES
                          May 28, 1987



                      Copyright (C) 1987 by
                        Gerald A. Monroe
                      All rights reserved.







GRABBER is currently marketed as a shareware program.

This means you have the opportunity to use and evaluate it
before you decide to buy.  If you find that it meets your
expectations, then you are strongly encouraged to send your
contribution of $5.00 to me at the address given below.

That's a very reasonable price, I think, for the very unique
and efficient utility you've received in this package.  Whether
you use your computer mainly for spreadsheet analysis, system
development, PC consulting or just playing games, I'm sure
you'll find GRABBER a very helpful tool.

From a programmer's perspective, GRABBER is a prime candidate
for your AUTOEXEC.BAT file.  It takes advantage of some of
DOS's most interesting characteristics to perform file I/O
safely and promptly whenever called upon.  GRABBER is fully
compatible with Borland's SideKick (tm), provided it is loaded
before that program, and has tested reliably in some of the
most treacherous memory environments I could cook up.

Avid users, please send your $5.00 contributions to:

            Jerry Monroe
            1241 Bunts Road
            Lakewood, Ohio 44107


If you have any questions or comments concerning GRABBER.COM,
and you have a modem, please leave a message for Jerry Monroe
on Norm Henke's PC-Ohio BBS at [phone].


GRABBER.COM -- Documentation and Technical Notes      Page 2 of 4



PART I
------------


GRABBER.COM, Ver. 2.10, is a memory-resident screen-capture
utility for the IBM Personal Computer and true compatibles.

Requirements:  IBM PC, XT, AT or compatible computer; one
               diskette drive; Color/Graphics display adapter;
               PC- or MS-DOS Version 2.0 or greater.

Unlike any other resident screen-capture program of which the
author is yet aware, GRABBER saves all text and graphics screens
produced by the Color/Graphics Adapter to an executable .COM
file.  In order to restore the saved image to the screen, it is
necessary only to execute the resulting program file at the DOS
command level.  Interpreted BASIC BLOADers and similar external
front-end methods are unnecessary.

To install the program in memory, type GRABBER [d:] at the DOS
prompt.  If the optional drive parameter is absent, GRABBER will
save screen images to the current logged drive and path whenever
the proper "trigger" keystrokes are detected.  If a valid drive
parameter is specified, all images will be saved to program files
on that logical or physical drive.

GRABBER does not recognize subdirectory names on the command
line.  Users of DOS versions 3.10 and above, however, may use the
external SUBST command to refer to any path in their hard disk
tree structures using a logical drive letter.

GRABBER cannot remove itself from memory, nor can the drive
parameter specified at installation time be changed without
rebooting the computer.


GRABBER.COM -- Documentation and Technical Notes      Page 3 of 4



Once GRABBER has attached itself to the resident portion of DOS,
it monitors all keyboard activity, waiting for the key combina-
tions of Ctrl-= (or Ctrl-1) before springing into action.  These
two keystroke combinations have different uses which are ex-
plained below.  Upon detecting the trigger, GRABBER steps in to
create a .COM program file containing the current text or graph-
ics image, either in the current default path or the pre-
specified path, as explained above.  Control is then returned to
DOS or the interrupted application.

If a capture request is made via the trigger keys and an error is
encountered while writing the "offspring" .COM file, the program
will signal the error condition by sounding three short beeps on
the PC's speaker.  The beeps mean that the image has not been
saved, and the user should correct the error condition and try
the capture again.  Common errors include trying to write to an
empty diskette drive, a write-protected or damaged disk, or a
disk whose directory or data space is already full.  (If GRABBER
signals an error while attempting to write to a hard disk, this
could indicate a very serious problem with the disk, and the user
should investigate the cause immediately.)

As noted above, GRABBER responds to two key combinations: Ctrl-=
and Ctrl-1.  To capture any text image and most graphics images
to disk, use Ctrl-=.

In some situations where a graphics captured is required, it may
be necessary to use Ctrl-1 instead.  The graphics mode of Lotus
1-2-3, Rel. 1 and 1A(*), is one such situation.  This program,
and others which may be encountered by the user, employ custom
video drivers to manipulate the display screen directly without
using the PC's built-in video services, which act rather slowly.

In normal operation (Ctrl-=), GRABBER depends on the computer's
BIOS data area to determine whether the display is in graphics or
text mode, and consequently, how large a screen file to create.
And since most programs keep the video BIOS informed of their
whereabouts, Ctrl-= normally gives the intended result.

The above-mentioned versions of 1-2-3, however, do not update the
BIOS when switching to graphics mode, so that using Ctrl-= in
this situation creates a screen file displaying only garbage.  If
Ctrl-1 is used, GRABBER will disregard the BIOS and assume that
the display is in the medium-resolution graphics mode, with color
enabled (Video Mode 4).

To clarify things, 1-2-3 Rel. 2.0 and above use Ctrl-= in any
video mode.  Rel. 1 and 1A(*) use Ctrl-1 only in graphics mode,
and Ctrl-= in text mode.


GRABBER.COM -- Documentation and Technical Notes      Page 4 of 4


PART II
------------


GRABBER.COM's "offspring," i.e. the screen programs it creates,
are named sequentially, SCREEN_A.COM, SCREEN_B.COM, and so forth.
The filenames will start over again at SCREEN_A every time the
computer is rebooted, or after the twenty-sixth snapshot in a
session (SCREEN_Z) is taken.  In order to prevent valued screen
files from being overwritten by new screens with the same name,
therefore, it is advisable to REName them at the first available
opportunity to something more descriptive.  (Of course, the
renamed file must retain the .COM extension to be recognized by
DOS as an executable program.)

Suppose that you have created a bar graph using 1-2-3 and
captured the image to disk, renaming the file GRAPH.COM.
Entering the command GRAPH [/F] at the DOS prompt will restore
the graphics image to the screen almost instantly.  (More on the
optional /F switch in a moment.) The GRAPH program then clears
the keyboard buffer and pauses until a key is pressed.  At this
point, the screen is cleared, the video mode and palette in
effect when GRAPH.COM was invoked will be restored, and the
cursor will reappear at the lower left-hand corner of the screen.

When invoked, GRABBER offspring always test the current video
mode with the mode required to display the images they carry
within them.  If the modes differ, the offspring programs will
blank the screen for about half a second (8 "ticks" of the system
clock) before displaying their images.  This technique eliminates
unattractive video "snow" patterns and the screen bounce which
occurs when the Color/Graphics Adapter switches modes.

If the modes are the same (for instance, you're in 80-column text
mode at the DOS prompt and invoke an offspring program carrying
an 80-column text screen), then the image will pop up almost
before your finger can leave the Return key -- if the program re-
sides on a RAM disk or hard disk, and only shortly thereafter if
on a floppy.

There are situations in which the user might wish to load an
image on the screen and return control to DOS immediately,
without having to press a key first.  This is where the optional
/F switch comes in.  In the example above, the command GRAPH /F
alters program execution so that the image is displayed as be-
fore, but the cursor will be placed at the lower left corner of
the screen right away and the DOS prompt will reappear there.
This method does not restore the original video mode, however,
and in this example the screen would remain in graphics mode when
a text mode might be desired instead.  The /F switch will probab-
ly be most useful for text-mode images such as menu screens.