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GDS - Graphics Display System
-----------------------------
Written by Paul Schmidt
Copyright (c) 1990,1991 Paul Schmidt
All rights reserved.
i. CONTENTS
-----------
Legal
Notices...................................................i
Introduction.............................................ii
Note About Use..........................................iii
What GDS Can Do For You..................................iv
What GDS Does NOT Do!.....................................v
Getting Started...........................................1
The GDS Text Screen.......................................2
Viewing Commands..........................................3
Slide Shows...............................................4
Antialiasing..............................................5
Dithering.................................................6
Command Line Parameters...................................7
Configuration File Details................................8
Common Problems And Solutions.............................9
Bug Reports..............................................10
Revision History.........................................11
ii. INTRODUCTION
----------------
One day, I was working on a simple card game and needed a
variety of cardback graphics. I referred to by library of
GIF files for some good scenery to put on the backs of cards
and found about 30 files which had nice scenery and pieces
which could be used quite nicely. Then I went to hell.
First, I converted a set of GIFs into IFF format and loaded
them into Deluxe Paint II Enhanced. Deluxe Paint is one of
the more powerful paint programs, and I was very surprised
to find that the brush size is limited to 64K (a forgivable
programming limit). After messing around with grids and
reducing chunks of images down in a nice orderly fashion, I
deleted the whole bunch. The time I spent messing with
Deluxe Pain (intentional typo) was actually more time than I
spent writing GDS.
I was very happy to find a program called 'GIFDESK' on a
bulletin board. It seemed to be just what I was looking
for, and it solved another problem for me also. The
documentation said it could reduce GIFs, but it was designed
for cataloging pictures, rather than just image reduction.
Great! Now I could get the graphics done, and I could
catalog my 150 megabytes of GIFs!
WRONG. GIFDESK is great for a simple catalog program, but
it doesn't do much for preserving images. The version I
have simply grabs dots from the original and slaps them in a
reduced space. Although I'm not sure, it seems to also use
a generic palette which further reduces the quality. In
short, all images get stomped on, some are very simply
unrecognizable.
Another problem which was mounting in the back of my mind
was that every GIF viewer I've seen either has mounds of
technical problems/quirks/bugs, or a user interface which
could make a commercial programmer vomit. ENOUGH ALREADY!
I was pissed off, in between projects, and wired on coffee.
I downloaded CompuServe's GIF file specifications for
encoding and decoding and got to work. A day later, GDS was
a reality.
I make no claims that GDS is everything. The general
outline of the program is based around a very few simple
concepts, and there is certainly room for improvement.
To my knowledge, there is no shareware program which can
reduce and/or catalog GIF images with any integrity at all,
until now.
iii. NOTE ABOUT USE
-------------------
This is a shareware program. That doesn't mean it's
free...but on the other hand, I'm not asking anything for
it's personal use either. If you decide you must force
money on me, I'll understand, but feel free to explore
without retribution.
This program was developed using tools and techniques which
have taken me many years to develop, and I hope it shows.
Because of this, the following points will be taken very
seriously:
** DO NOT ** derive benefit from this software
professionally in any manner. DO NOT sell it. DO NOT
bundle it with any combination of products sold for money
(this does not include shipping charges for shareware
distributors).
BBS SYSOPS: Please use GDS to catalog your GIFs for your
users! I would like to know you are using it, how you like
it, and information about your setup. I am very interested
in providing good software (like this) to sysops, but I'm
not about to write any more unless you all communicate with
me. Again, I don't want money, I just want to get your
feedback. (See the BUG REPORTS section for my mailing
address.)
PEOPLE WHO COMPLAIN: There are advanced parts of the GDS
user interface which could use some simplification. While
this is true for you advanced users, I'm estimating that 95%
of the users won't do much more than double click with a
mouse or do slide shows. These two facets of GDS are very
simple. As for the parts which could use help? When I have
a few weeks to blow, I'll improve them.
iv. WHAT GDS CAN DO FOR YOU
---------------------------
1) GIF VIEWER - GDS is a very intuitive graphics file
viewer. It has a user interface based on experience with
GUI design. If you find a graphics viewer which is easier
to use, please let me know and I'll see what I can do.
2) FILE FORMATS - GDS reads GIF, LBM, PCX, and RIX
files. It can write GIF, PCX, and RIX files directly from
the screen. Other formats may be added in future versions.
3) SLIDESHOWS - GDS can easily allow you to queue up
almost any number of GIF files to show in a repeated
sequence.
4) IMAGE PROCESSING - GDS can scale images independently
in both axis, which comes in very handy if you're trying to
reduce, enlarge or correct image scaling. NOTE: Give system
operators a break and don't use GDS to make larger GIF files
for more download credit.
5) ARRAY CATALOGS - GDS has a very good image
cataloging section which arranges arrays of files on the
screen. If you are a system operator of a BBS, this is a
great way to provide previews of many images to your users.
6) SCREEN CONVERSION - GDS can lock a screen mode,
reduce and enlarge images to fit, or scale to any
dimensions. 256 color images can easily be converted to 16
color images with antialiasing and dithering to ensure
spatial color consistency.
7) MOUSE SUPPORT - GDS is very mouse supportive.
Although everything can be done with the keyboard (a couple
of things can ONLY be done with the keyboard), there is
extensive mouse support in GDS. Unless you are writing or
rescaling images, GDS is extremely quick with a mouse.
v. WHAT GDS DOES NOT DO!
------------------------
1) TIFF FILES - GDS makes no attempt to read or write
TIFF files. I sat down with some TIFF documentation one
night to support the TIFF file format, and spent several
hours setting up a code skeleton. After being very
confused, I finally realized how the format worked, and
vowed never to support it. In my opinion, TIFF is the most
ridiculous image format I've seen thus far. Use someone
else's program to convert TIFF files into something
supportable, and hopefully, TIFF will disappear forever.
2) WRITING LBMs - GDS doesn't write LBM files. It's
something I could do, but life is seldom fair. GDS let's
you write GIF, PCX, and RIX files. Fortunately, Deluxe
Paint II Enhanced will read PCX files. If you really need
this support and you send me lots of money, I'll support LBM
files.
1. GETTING STARTED
------------------
Since you can read this, you must have either gotten GDS as
a set of files, or already UNZIPped it out of it's original
ZIP file.
GDS can quickly be started by typing 'GDS' followed by
'Enter'. GDS should run with no command line options. GDS
can also be started from any path by specifying it's path on
the command line. It can also be run if it's in the
machine's PATH= list.
GDS parses file/path specifications and runtime switches as
command line parameters. Any number of paths/files may be
specified to GDS. However, if no actual files are found to
work with, GDS will say so and exit to DOS. GDS can't run
without files to work with. The following command line is
typical and completely safe:
C> GDS i:\dp\*.lbm j:\GIFs openscrn.gif
The first path specifies all LBM files in the 'DP' directory
on drive I:. The second path specifies all readable files
in the 'GIFS' directory on drive J:. The third path
specifies the single file 'OPENSCRN.GIF' in the currently
logged directory. If no path names are given, the current
directory is used ('*').
If you have problems getting GDS to run, refer to the
section titled 'Common Problems and Solutions'. The most
common problem is an unsupported video board.
2. THE GDS TEXT SCREEN
----------------------
After configuring GDS and getting it to execute properly,
the user is presented with a screen containing a file
display consisting of file names, extensions, and file sizes
in a columnar format. The top line of the screen always
shows the version number and copyright message.
Getting out of GDS is easy. Just hit 'Esc' or click on the
'Quit' button.
The user may view images using the keyboard or the mouse to
scroll around through the list and pressing 'Enter' (or
double clicking) on a file. The space bar (or mouse single
click) toggles the selection state of the file under the
file cursor. Mouse users can drag the mouse from one file
to another to select all files in between. Mouse users may
also toggle ranges of files by holding down the shift key
and clicking/dragging, just like the Macintosh user
interface.
For keyboard users, pressing the 'Enter' key starts a view
in the current view mode (single, slides, or arrays).
Pressing 'Enter' does not change the selection state of ANY
of the files in the file list. Use the space bar to toggle
the selection state of files.
For mouse users, double clicking on a file will display that
file alone in single view mode, regardless of the current
view mode. Use the 'Enter' key or view button (see below)
to initiate slide shows or arrays.
Several buttons and menus are displayed in the second line
of the screen and on the bottom line. These areas are
referred to in this documentation as 'Menu Areas'.
In between the file display and the bottom menu area are two
lines displaying detailed information about the 'Current
File'. This is referred to as the 'File Status Area'. As
you move the cursor around the screen, you will see these
two lines display information about each file you pass over.
This information includes the complete path and file name of
the file, it's screen resolution, number of colors, and the
exact file size in bytes.
On the right side of the status area, the total number of
files and number of files selected are displayed
parenthetically. The number of files selected will not be
displayed unless files are currently selected.
Directly to the right of the file status area is a help
message which says "'Enter' views current selection"
enclosed in a box. This area is referred to as the 'View
Button'. The view button is important to keyboard users
only in that it tells them that using the 'Enter' key will
show them a picture. To mouse users, this area may be
clicked on to display whatever is selected.
The view button gives mouse users added flexibility in that
it allows them to intuitively get what they want. The
function of the view area is similar to using the 'Enter'
key or double clicking to view a file, but takes the current
selection criteria into account when deciding what to do.
The view button works like this: If there are selected
files, the view button starts a view in the current view
mode (slides or arrays). If there are no files selected,
the view button will treat all files as if they are selected
(instant slide show or arrays).
Using the menus in GDS is simple from a keyboard or mouse.
From the keyboard, hold down 'Alt' and then hit the key
which matches the first highlighted character in the menu or
button you want to change. If the menu or button you have
selected has two or less functions (like the 'MOUSE:' or
'Quit'), then the state of the button just changes (in the
case of 'Quit', the program just terminates). If there are
more than two options, then a menu will appear with the
default selection highlighted. You are free to use the
arrow keys to navigate the menus and press 'Enter' to select
your option. You may also hit 'Esc' to cancel selecting
from a menu.
Using the menus and buttons with the mouse is even easier.
Simply move the mouse pointer over the menu or button and
hold down a mouse button. If the menu has two or fewer
options, the state of the button simply changes ('Quit'
exits immediately). If there are several choices, a menu
will appear. Keep the mouse button down and drag the mouse
until the mouse pointer is over the option you want (the
option should be highlighted). When the option you want is
highlighted, just let go of the mouse button. The state of
the menu will change on the screen.
The functions of each menu or button are discussed below:
Quit This button exits the program.
AutO/LOck This button shows the state of screen mode
locking. The default graphics mode is normally
meaningless unless this button is in the 'LOck' state.
Locking the screen mode forces images to be displayed
in the graphics mode selected in the 'RES:...' menu.
RES:... This menu allows the selection of the default
graphics and text modes. The default graphics mode has
no effect unless the 'AutO/LOck' button is in the
'LOck' state.
VIEW:... This menu allows the user to choose between
'Single' images, 'Slides' (slide shows), and 'Arrays'.
Note that with the mouse, double clicking always
produces a single view regardless of the state of this
menu.
LABELS: This button tells whether or not labels are added
to the bottom of array images. It has no significance
to single views or slide shows.
BORDERS: This button tells whether or not borders are drawn
around array images. It has no significance to single
views or slide shows.
ALIAS:... This menu allows the user to select what level of
antialiasing is performed for reduced images (see
'ANTIALIASING' section below).
AboUt This menu displays interesting information about
GDS. It has no function except to entertain you.
SORT:... This menu allows the user to select the sort order
for the file display. Selecting a new sort order
immediately causes the file display to be rearranged.
MOUSE:... This button toggles the mouse between a bitmapped
text cursor and a character cursor. Some video
displays do not conform to the VGA hardware standard
for text character sets and may cause GDS to display a
garbled mouse cursor. If this happens, click on the
'MOUSE:; button. Note that the state of the mouse can
be set in the configuration file so you don't have
click the 'MOUSE:' button every time you run GDS.
PALETTE: This menu controls the palette generation for
array images. GDS will use no more colors in the
palette than are specified in the 'PALETTE:' button.
This setting normally has no effect on single views or
slide shows. Note that this number can be set in the
configuration file so you don't have to set it every
time you'd like to create reduced palette arrays.
DITHER: This menu allows the user to specify the level of
dithering to be used when generating array images. No
dithering means that GDS will not try to increase color
consistency. Two color dithering generates checker-
board patterns which are usually imperceptible. Uneven
dithering is more obvious than two color dithering, but
greatly enhances the general look of 16 color
renditions of images which use more than 16 colors.
FILESHOW: This menu allows the user to toggle different
elements of the file display on and off. Note that
these elements can be set on or off in the
configuration file so you don't have to set it every
time you run GDS.
3. VIEWING COMMANDS
-------------------
GDS has some interesting features when images are viewed
alone. Images can be viewed alone by using 'Enter', or by
double clicking a file with a mouse.
Slide shows will not allow the user to do any of these
functions. Arrays, on the other hand, will let the user
write GIF, PCX, and RIX images ('Alt-W', 'Alt-P' and 'Alt-
R'). Note that the 'Alt-W', 'Alt-P', and 'Alt-R' commands
can be set up with the '/W###' option to automatically write
a run of array images ONLY in the array view mode.
For those of you who realize that the user interface for
these extended view functions isn't very nice,
congratulations. Perhaps if you complain enough, I'll put
in a real user interface.
When viewing a single image or a carefully generated array
image, it is sometimes necessary to adjust the color
content. The F1 through F10 keys adjust the levels of each
color bar, contrast, and brightness. Use Shift-F1 through
Shift-F10 to reset the respective levels. Note that GDS
does not destroy the palette during adjustment. There is no
palette degradation during these adjustments.
Enter Always exits view mode.
Esc Always exits view mode.
Space EXIT view mode, unless scaling has been changed
using the arrow keys or the Alt-Z (zoom)
functions.
Alt-W Immediately starts writing a GIF file titled
"GDS###.GIF". The number used in place of '###'
is either 000 or whatever number was specified
with the '/W###' command line parameter. This
function will not overwrite existing files.
Alt-P Exactly like Alt-W, but writes "GDS###.PCX"
instead. This may come in handy for those of you
using Deluxe Paint II Enhanced.
Alt-R Exactly like Alt-W, but writes "GDS###.SC*"
instead. This may come in handle for those of you
using RIX's imaging software. Note that GDS
supports RIX 'UNCOMPRESSED' format only. RIX
Software is not releasing any information about
it's compressed formats. If you would like to see
compressed RIX files read, don't ask me -- please
ask RIX to allow developers to support it.
Arrows Typing the arrow keys adjusts the lower right hand
corner of the destination image rectangle. Arrow
keys alone moves the lower right corner by two
pixels at a time, and holding the shift key down
while typing the arrow keys moves it by 20 pixels
at a time. If you manage to get the image messed
up enough so you want to start over, just hit the
space bar and the image will redraw at it's normal
scale. This function is useful when used with
Alt-F to fine tune the scale for image reduction.
It's also very useful for correcting the size of
images that are stored crunched in the vertical
scale. (Why do people do that to image files?)
Alt-Z Start 'zoom' sequence. ONLY WORKS WITH A MOUSE.
Use 'Alt-Z' as follows: (1) Press 'Alt-Z'. (2)
Move the mouse pointer to the upper left of a
rectangle to zoom to the full screen size. (3)
Press and hold down a mouse button. (4) While
holding down the mouse button, drag the mouse
pointer to the lower right of the rectangle to
zoom to the full screen. (5) Let go of the mouse
button. If something goes wrong or it doesn't
seem to work correctly, just hit the space bar and
the image will redraw to it's normal scale. The
'Zoom' function doesn't work all the time, and I
haven't bothered to figure out why.
Alt-F Fit to screen. This function ATTEMPTS to rescale
an image to fit into the full screen. It is
useful for scaling images down, sometimes... It
doesn't work all of the time and suffers from the
same problems that the 'Alt-Z' function does. If
it screws up and draws something strange, just hit
the spacebar and the image will redraw to it's
normal scale.
F1/F2 Reduce/Increase palette red level.
F3/F4 Reduce/Increase palette green level.
F5/F6 Reduce/Increase palette blue level.
F7/F8 Reduce/Increase contrast.
F9/F10 Reduce/Increase brightness.
Shift-F1 Reset red level to that of original image.
Shift-F3 Reset green level to that of original image.
Shift-F5 Reset blue level to that of original image.
Shift-F7 Reset contrast to that of original image.
Shift-F9 Reset brightness to that of original image.
Alt-F1, Alt-F2, Alt-F3, Alt-F4, Alt-F9, Alt-F10
These keys do all sorts of neat stuff, but I'm not about to
explain why or how. Ignoring these is a good
idea. Have a nice day.
4. SLIDE SHOWS
--------------
GDS has two separate methods of generating slide shows. The
first is to select a range of files from within the normal
GDS user interface and set the 'View:' menu to 'Slides'.
When GDS is in set this way, normal viewing of images
results in a slideshow (except mouse double clicks; see
VIEWING COMMANDS).
The second method is to specify the '/S' option on the
command line. GDS will bypass the normal user interface and
immediately start a slide show using any files specified on
the command line.
The '/O' option is normally ON (1), which sorts the file
list when the '/S' option is specified. Specifying '/S0' on
the command line will prevent GDS from sorting the file
list.
The '/Z' option specifies the delay in 100ths of seconds
between slides. Two seconds, for example, would be
specified using '/Z200'. If '/Z' is not specified, GDS will
wait for at least 5 seconds between each slide.
It is often necessary to give a slideshow on a very specific
set of files which may be inconvenient to enter on the
command line. The '@<FILE>' option is used to tell GDS to
read a list of filenames from <FILE>. Using the '@<FILE>'
option can save you a lot of time and allow you to customize
your slideshows to your heart's content. An example of a
typical planned slideshow is as follows:
C> gds /s @filelist /o
The first option ('/s') tells GDS to do an automatic slide
show. The second option ('@filelist') tells GDS to read the
file 'filelist' for a list of files to show. The third
option prevents GDS from sorting the file list.
5. ANTIALIASING
---------------
Antialiasing is a term used to describe the color correction
applied to pixel hues in order to maintain the overall
appearance of an image. Most often, antialiasing means
adjusting the colors along partially covered pixels when
drawing a line on a bitmapped screen.
GDS uses antialiasing only when reducing an image. It
doesn't smooth out transitions between enlarged pixels.
Perhaps in a future version, enlargement smoothing may be
supported.
GDS uses a very high performance antialiasing technique
which scans colors from many original image pixels and
combines them to form a single destination pixel. What this
gives you is an extremely accurate representation of the
original image, but using far less dots to do it.
An interesting side effect of antialiasing is that it tends
to reduce the size of the resulting GIF file. Originally, I
expected the file size to increase, but was fascinated when
it dropped by about 9.6% for each dimension of antialiasing
applied.
6. DITHERING
------------
GDS normally mixes colors together when appropriate in order
to increase the apparent color resolution. A good example
of this is when an image has a section which fades evenly
from one color (like red) to another color (like blue). The
result in the middle is purple. When images are reduced and
combined on the same screen, the demand for colors is high.
In high resolution GIF images, there are 256 colors per
picture. If you try to mix 80 pictures together, you would
need 20480 colors in order to represent the pictures without
any hardware color distortion.
When GDS doesn't have a color available (like purple from
the example above), it looks for two colors which when
displayed closely together appear to have the color of the
original pixels. This results in an almost imperceptible
change from the original color in 256 color modes.
Almost as interesting as the effect antialiasing has on
resulting GIF file sizes, dithering increases GIF file size
by about 9.6% for each level of dithering applied.
7. COMMAND LINE PARAMETERS
--------------------------
All command line parameters may be prefaced with a forward
slash ('/') or a dash ('-'). Command line parameters are
processed in the order they are received. Basically, they
act like most other command line scheme.
Available command line options are as follows:
/A<n> Set default antialiasing level (0-2)
/B<n> Set default mouse display mode (0-1)
/D<n> Set default dithering level (0-2)
/F#### Set default file display options
/G<mode> Set default graphics display mode
/H or /? Display help screen with these switches listed
/I<n> Set early interlaced fill mode
/L<n> Set default labels on/off switch
/M<n> Set maximum number of colors in generated palette
/O<n> Set sort flag for automatic slide shows (1=sort)
/S<n> Slideshow mode (no user interface, just slides)
/T<mode> Set default text display mode
/V<n> Set vertical orientation mode
/W<n> Set automatic array stream write after first Alt-W
/Z<n> Set delay in between slides in slide shows
/<NAME> Force graphics support
/512 Force support for 512K VGA modes
@<FILE> Get list of files from FILE.
/B<n> This option sets the mode in which the text mouse
cursor is displayed. When this option is set to 0, GDS will
display a highlighted character as a text mouse cursor.
When this option is set to 1, GDS will attempt to remap
characters in the EGA/VGA character set to implement a
graphics cursor in text mode. The default setting of this
option is determined at runtime, and depends on the hardware
you have. If your cursor doesn't look right, try changing
the /B option in your GDS.CFG file.
/F#### This option allows the user to specify what
information should be displayed in the file list at startup.
The four number (or pound) signs each hold a place for a 1
or a 0, indicating whether or not the given option is on or
not. The list of file options is as follows:
/F1??? Display file extension (default=0)
/F?1?? Display image resolution (default=0)
/F??1? Display number of bits per pixel (default=0)
/F???1 Display file size (default=1)
/G<mode> This option sets the default graphics mode to be
used for display. The format of <mode> should be
<n>x<n>x<n>, where the first value is the screen width, the
second value is the screen height, and the third number is
the number of bits per pixel (or number of colors). The
number of bits per pixel is optional for this option. The
default setting for this option is '/G640x480x8'.
/H or /? This option displays the runtime help screen.
/I<n> This option sets the 'early interlaced GIF fill
mode' option. When interlaced images are drawn, GDS can
fill in the breaks in between interlaced lines so the viewer
gets a better image of what the the picture is as fast as
possible. It appears that this was one of the intended uses
of interlaced image format in the original GIF
specification, but no other GIF viewers seem to do this.
When this option is enabled (1), interlaced images draw a
bit slower overall, but the user can see the general content
of the picture in about one quarter of the time it takes to
read the entire image. The default value of this switch is
ON (or 1).
/M<n> This option puts a ceiling on the number of colors
GDS is allowed to use when it generates common palettes for
combining many GIF images into arrays of images. This
option is significant because the resulting file size of GIF
files written with one bit less per pixel is about 9.5%
smaller than the original number of bits per pixel. This
means that a 128 color image will be approximately 91% of
the size of the similar 256 color. The disadvantage to
limiting the palette is that the color resolution drops, and
therefore the picture quality suffers.
/O<n> This option sets the sort flag for automatic slide
shows (/S). This option has no effect when the '/S' option
is not specified. To sort the file list before an automatic
slide show, specify /O1. To leave the file list unsorted,
specify /O0. The default value of this option is ON (or 0).
/S This option specifies automatic slide show mode. In
automatic slide show mode, no user interface is offered, and
a slide show starts immediately after startup. See the
'@<FILE>' option for a useful way to specify exactly what
files to show.
/T<mode> This option sets the default text mode to be used
for display. The format of <mode> should be <n>x<n>, where
the first value is the number of character columns, and the
second value is the number of screen lines. The default
value for this mode is '/T80x25'.
/W<n> This rather quirky option sets the state of a mode
wherein GDS will continue to generate and write array images
(GIF, PCX, or RIX) after the first time you press Alt-W,
Alt-P, or ALT-R, respectively. Using this option, GDS will
run through hundreds of files and generate an image for each
complete array screen. The default setting for this option
is OFF (or 0).
/Z<n> This options specifies the number of 100ths of
seconds to delay in between slides during a slideshow. The
default value is 5 seconds (91). The delay between slides
can be completely eliminated by setting this option to 0.
/<NAME> This option is used to force GDS to assume it has
the named video card. Normally, this is not necessary or
advisable. USE THIS OPTION WITH CARE. There is no telling
what could happen if you force a graphics card which
conflicts with the hardware you actually have. The
following video cards are currently defined:
/EGA Standard EGA or 100% compatible
/VGA Standard VGA or 100% compatible
/AHEAD Ahead Systems Chipset (type A)
/AHEADB Ahead Systems Chipset (type B)
/ATI ATI VGA Wonder
/CHIPS Chips and Technologies Chipsets
/EVEREX Everex Systems
/GENOA Genoa 6000 series
/OAK Oak Technologies
/ORCHID Orchid Technologies
/PARA Paradise Systems
/TRIDNT ATI Prism Elite (Trident Chipsets)
/TSENG Tseng Laboratories Chipset
/TSENG4 Tseng Laboratories Chipset (4000 series)
/VESA Standard VESA BIOS Interface
/VID7 Video Seven VRAM or FASTWRITE VGA
/ZYMOS Zymos HiRes 512K VGA
/512 Force support for 512K VGA. If your video card has
512K of display RAM and you are unable to get GDS to support
modes requiring 512K, try using the '/512' command line
switch. If using this option is successful, you may wish to
place this switch in GDS.CFG so you don't have to type it
every time you run GDS. The default setting of this switch
is 0 (off), and if /<NAME> is not specified, this switch is
set by GDS when it tries to automatically detect what type
of video adapter is present.
@<FILE> This option reads a list of image files from
<FILE>. FILE may be any valid path and filename. This is
usually used with automatic slide shows (see '/S').
8. CONFIGURATION FILE DETAILS
-----------------------------
Unless you know what you are doing and are familiar with
GDS, please stay away from the configuration file.
GDS.CFG is set up to define all video modes for all display
cards, and to give the user the ability to specify command
line arguments which he doesn't feel like typing all the
time. GDS.CFG will be read from the current directory
first, and then from the execution path. If GDS.CFG is not
found in either location, the program will object.
Any semicolon (';') found in the input stream is interpreted
as a comment. The semicolon and anything after it on the
same line is ignored. It is simple to disable lines in the
configuration file by placing a semicolon in front of it.
Primarily, tabs, spaces, and blank lines are ignored.
There are two types of configuration lines. The first
defines a video mode, and the second specifies automatic
command line options. The format of the video modes is as
follows:
A, B, C, D, E, F, G, H, I, J ;optional comment
A) Name of the video card
B) Horizontal screen resolution (number of columns)
C) Vertical screen resolution (number of lines)
D) Number of bits per pixel (or 0 for text mode)
E) AX register on INT 21h call to set video mode (see I)
F) BX register on INT 21h call to set video mode (see I)
G) CX register on INT 21h call to set video mode (see I)
H) DX register on INT 21h call to set video mode (see I)
I) This option has one of three meanings:
1) 0 if video mode is a standard graphics mode
2) 1 if video mode is directly programmed (VGA
register compatible cards only!
3) The base address of the screen if the video
mode is a text mode (indicated by 0 bits per
pixel)
J) Dot Mode (0=normal, 1=ATI 16 color chunky)
To specify automatic command line options, add a line to
GDS.CFG similar to the following example:
AUTO, /m64 /t132x44 ;limit palette to 64 colors
This example will behave as if you typed '/m64 /t132x44' on
the command line. All automatic command line parameters
will be processed AFTER the actual command line parameters.
There are examples of each of these two types of command
lines in the included GDS.CFG file. There are also comments
in the file which should offer more information.
9. COMMON PROBLEMS AND SOLUTIONS
--------------------------------
The following PROBLEM and SOLUTION pairs are included to
help you figure out what's wrong with your setup or GDS.
Each individual entry came from the experience of supporting
people who have problems with GDS.
PROBLEM: After GDS starts, it keeps doing something with
the disk drive which makes me paraniod! I don't like it and
I want it to stop.
SOLUTION: This inquisitive behavior is perfectly normal for
GDS. Don't worry, it's not a virus deleting your files!
GDS reads the number of bits per pixel and screen resolution
for every file in the file list whenever you haven't done
anything interesting for a few seconds. It will read about
15 listings and then pause for a couple of seconds and
repeat this pattern until it has read every file. It does
this so you don't have to wait for a long time if you want
to sort by something which needs to be read from every file
(like number of bits per pixel or screen resolution). If
you do anything with the user interface or hit any keys, GDS
will stop reading these files instantly.
PROBLEM: The file cursor flashes on and off very fast on
some files and GDS will not display them.
SOLUTION: GDS does this because GDS thinks there is an error
in the file. If you don't believe there's an error in the
header of the file, try displaying the file with another
viewer. Send a note to Paul Schmidt if you find a file that
other viewers will view and GDS won't.
PROBLEM: GDS won't run, and gives me an error that says it
doesn't know what kind of video card I have.
SOLUTION: If you're sure you have a video card which is
compatible with the listings in GDS.CFG, then use the
'/<NAME>' option to tell GDS what card to use. You will
also have to use the '/512' option if you have 512K of video
RAM. If you don't know what kind of video card you have,
then you probably have one which is incompatible with GDS.
If you'd like to see the card supported, send me the
technical reference information with a brief cover letter.
If you really know what you're doing, you can add modes to
an existing board. None of these suggestions is supported.
PROBLEM: GDS displays the top part of 256 color images
fine, but the bottom part is either black or garbled.
SOLUTIONS:
A) Try locking each extended screen mode in the 'Res:'
menu and displaying files with it. See which ones screw up.
B) Check to see if there is enough RAM on your video
card to use the display mode you're trying to go into. If
not, you can disable the offending mode using a semicolon
(';') in GDS.CFG.
C) Look in GDS.CFG to see if the screen modes which
screw up are actually supported by your video card, and not
by a different video card. You may have to experiment with
the GDS configuration file to get a reliable list of modes
to use.
PROBLEM: Some pictures I have are squished to the left of
the screen when I view them with GDS.
SOLUTION: Yeah. Some are. GDS will not modify the literal
dimensions of a picture unless the picture is TOO BIG to fit
on the screen (if so, GDS will scale it down). These
squished images were written with a screen size which has a
much greater aspect ratio horizontally than the screen you
have. Most of the time, you can simply hit 'Alt-F' to fit
the image into the screen. Sometimes, however, people
(morons) store the images squished into normal screen sizes.
When 'Alt-F' doesn't work, try using the arrow keys (with
and without holding down the shift key). To actually FIX
these images, just manipulate the image until it fits nicely
into the screen and hit 'Alt-W' or 'Alt-P'. This will write
the image as GDS###.GIF or GDS###.PCX. Go back out to DOS
and delete the old file and rename the GDS### to the name of
the old file.
PROBLEM: I see garbage on the text screen around the mouse
pointer whenever I move the mouse around. It is very
annoying.
SOLUTION: You must have a VGA which isn't supported by the
graphic/text mouse pointer. Edit GDS.CFG and add the line
'auto, /m0'. This will force the mouse to be a character,
rather than an arrow in text mode.
PROBLEM: The screen colors are ugly.
SOLUTION: Write a TSR which can tell if GDS is loaded and
monitors the BIOS screen mode and text screens. Write very
involved and optimized code which scans the text screen and
finds the places where GDS writes characters and change
their attributes using a user specified color set. When
someone get's this TSR running nicely, I'll add an easier
way to change GDS's screen colors. IN OTHER WORDS, LIVE
WITH THE COLORS.
10. BUG REPORTS
---------------
Bugs suck. But, like most things, they happen. I would
just like to note that I've taken every precaution to limit
bugs, and I think I've been thorough in my quest for a bug-
free program. HOWEVER -- bugs are inevitable.
The biggest area I'm suspecting bugs in is video support.
There is support for some 60 or so super vga cards. There
is code which the manufacturers say should work.
Unfortunately, I can only test what I have. I would be
interested to find out if certain cards do or don't work.
I have tested this software with the Video 7 VRAM VGA, Video
7 1024i, ATI Wonder+, Orchid Pro-Designer w/1MB, TVGA
(Trident) w/1M, Paradise VGA+ w/256K, and Oaktech 256K VGA.
I have not personally tested it with the other cards, but
have heard of much success. I have heard of bizarre
problems with some Paradise boards and am looking for
information relating to them.
Below I give my address. This is where you should write if
you do find a problem. I make no guarantees on ever fixing
a reported bug, regardless of it's nature.
GDS Graphics File Viewer
1194 Spring Valley Commons
Livermore, CA 94550
11. REVISION HISTORY
--------------------
1.00 02-10-91 First release, hope you like it.
---- -------- --------------------------------
--> No bugs reported yet. (I'm plugging my ears.)
1.01 02-11-91 Wow! that was fast!
---- -------- -------------------
--> 'Sort:' menu in earlier versions could easily lock up
GDS when used to sort by 'Bits per pixel' or 'Resolution' if
GDS had not yet read file information for all files in file
list. Although I haven't seen it, this bug may cause stack
overflows, 386 exceptions, and all sorts of other
unpredictable stuff.
--> Palette generation for array images is much more
accurate for images with varying numbers of bits per pixel.
In prior versions, images with fewer bits per pixel were not
represented equally among pictures with many bits per pixel.
This problem has been eliminated by padding smaller palettes
to bias the importance of their individual color ranges.
--> When displaying a 2, 4, 8, or 16 color image in single view
mode and the screen format used to display the image was an EGA
mode, some VGA boards would handle the EGA palette and VGA color
registers inconsistently. This occationally caused a color or two
to be incorrect. GDS now resets all EGA palette registers and all
VGA color registers every time the palette is set, which seems to
have corrected the problem.
NEW! Changed behavior of mouse clicks in file list when 'View:'
mode is set to 'slides'. Users tend to want to point at a file and
add it to the list rather than deselecting all other entries in
favor of the one their clicking on. So from now on, when you're
doing slides, remember that the mouse toggles files!
--> Fixed small moving button click problem in array setup.
1.02 02-12-91 QUIX RIX FIX.
---- -------- -------------
NEW! Added RIX support through the Alt-R command. Note that GDS
can only support the 'UNCOMPRESSED' RIX file formats as RIX
Software is not releasing any information about their compressed
file format. If you would really like to see support for
compressed RIX files, don't ask me -- ask RIX Software.
--> Fixed PCX file write for 16 color screen modes. In previous
versions, GDS would write odd images with the bits in the bytes
flipped around, and possibly the plane order reversed. This bug
may be a reflection of how much time I spent writing PCX support.
GDS now reads and writes PCX files correctly in all screen modes.
1.03 02-13-91 Slideshow fixups.
--> Corrected bug in slide shows which could incorrectly display
images which had been read completely into EMS before being
displayed. This bug is more common when the user hits the space
bar to bypass the slide show delay. Earlier versions of GDS could
display slide shows with image misalignment/fracturing or even
garbage in horzontal bands of images.
2