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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 disgusted, 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 time, 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 (very quickly implemented) user interface based on many years of GUI experience. If you find an easier graphics viewer, please let me know. 2) FILE FORMATS - GDS reads GIF, LBM, PCX, RIX, and MAC files. It can write GIF, PCX, and RIX files directly from the screen. Other formats may be added in future versions. If you really need a format supported for something, FAX or write me a note. 3) SLIDE SHOWS - GDS can easily allow you to queue up to 2800 images to show in a repeated sequence. At 5 seconds per image, that's just under four hours without repeating an image. GDS reads successive images ahead of time into EMS or system RAM to minimize draw time, increasing the appearance of the slide show. 4) IMAGE PROCESSING - GDS can scale images to almost any size. This capability 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) ARRAYS - GDS has a very good image cataloging section which reduces and labels arrays of images on the screen. GDS creates spatially optimized palettes, uses two levels of dithering and two dimensional antialiasing to reduce color distortion. GDS can reduce up to 2304 images onto a single 1024x768 graphics 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 and zoom to almost 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 (does that make it cheezy?). Although almost 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 concentrating for quite a while, I finally realized how the format worked, and vowed never to support it. In my humble opinion, TIFF must be the most ridiculous image format I've ever seen. Use someone else's program to convert TIFF files into something reasonable, and hopefully, TIFF will disappear forever (wishful thinking). 2) WRITING FORMATS - GDS doesn't write LBM or MAC files. It's something I could do, but haven't and don't have much of a use for. GDS writes GIF, PCX, and RIX files. Deluxe Paint II Enhanced (LBM files) will read PCX files. If you really need support for writing a format, FAX or write me a note and we'll discuss it. 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 function, 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 by pressing 'Enter' (or double clicking) on a file name. The space bar 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 can click on a file, which will deselect all currently selected files (when in single view mode) and select the file under the mouse cursor. When in single view mode, mouse users may toggle ranges of files by holding down the shift key and clicking/dragging, just like the Macintosh user interface. In the slide show mode, the mouse always acts like the shift key is held. For keyboard users, pressing the 'Enter' key starts a view in the current view mode (single or slides). 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. (MOUSE USERS: It's usually easier to set up fragmented slide shows with the keyboard!) 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. 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 the file cursor is moved through the file list, GDS displays information about each file under the file cursor. 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 file status area, the total number of files and number of files selected are parenthetically displayed. 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" in a rectangle. This area is referred to as the 'view button'. This button is not important to keyboard users, except that it tells them what to do to display an image. The view button gives mouse users added flexibility because clicking it starts a slide show. If there is more than one file selected or NO files selected, the view button starts a slide show regardless of the current view mode. If there is one file selected, the view button will do a single view. For mouse users, it's easiest to use the 'View:' menu to change the behavior of single clicks in the file list (see above) and use the view button to start slide shows. 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 (or click on it with a mouse). If the menu or button you have selected has two or less functions (like the 'MOUSE:' button), then the state of the button just changes. If there are more than two choices, then GDS presents the user with a menu. When using the keyboard, the default menu selection will be 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. With a mouse, just click (or drag and let go on) your choice. To cancel selection with a mouse, just click (or let go) outside of the menu area. 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. This is handy when reducing large images down to fit in smaller screen modes, or reducing 256 color images down to dithered 16 color images. 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 and 'Slides' (slide shows). When this menu is in 'Single' mode, any selection of a file will deselect all other files first (unless the 'Shift' key is held). When this menu is in 'Slides' mode, mouse clicks never globally destructive to selections, but rather always modify the selected state of files. 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. Since the 'label' and 'border' buttons have been added to the array generation screen, this button may disappear to give way to a more meaningful button or menu in the future. BORDERS: This button tells whether or not borders are drawn around array images. It has no significance to single views or slide shows. Since the 'label' and 'border' buttons have been added to the array generation screen, this button may disappear to give way to a more meaningful button or menu in the future. ALIAS:... This menu allows the user to select what level of antialiasing is performed for reduced images (see 'ANTIALIASING' section below). Hint: The default antialiasing (horizontal only) is almost as fast as no antialiasing at all. However, high quality image reduction can take as much as 10 times longer depending on the level of reduction. In general, considering the increase in image quality, it's always worth using horizontal antialiasing, and usually worth using high quality image reduction. 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. Note that selecting sort orders which require the resolution or number of bits per pixel will force GDS to research this information before a sort can be done. This is annoying sometimes, but hey...you can't sort information you don't have. GDS buffers the resolution and number of bits per pixel so that it only has to read it once. 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. Using the command line option is also useful in that it is not limited to a 'nice' number. The user can specify any number (like 27) for the number of colors to use. 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 functionally imperceptible except in low resolution graphics modes. Uneven dithering is more obvious than two color dithering, but greatly enhances the general look of 16 color renditions of images which start out with many more colors. Hint: There is almost no speed difference in using dithering. The biggest delay is the delay just before the image is read where GDS generates it's conversion table. There is almost no speed difference in putting up raw pixels vs. dithered pixels. In short, dithering doesn't slow GDS down perceptibly. 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 allow the user to 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. Array images can also be adjusted with the color controls (F1-F10, ',', and '.'). For those of you who realize that the user interface for some of the extended view functions isn't very nice, congratulations. Perhaps if you FAX me something, I'll improve it. When viewing a single image or a carefully generated array image, it is sometimes handy to adjust the palette manually. The F1 through F10, ',', and ',' keys adjust the red leve, green level, blue level, image contrast, image brightness and color level. Reset the individual levels by holding down the shift key and using the same keys. Every time a level is changed, the entire palette is recalculated from the original to prevent eventual palette degradation. Esc Always exits view mode. Enter Exits single view mode. During slide shows, 'Enter' exits if a slide is being drawn. Space When viewing a single image, pressing the spacebar exits back to the file screen unless the scale of the image is not exactly the same as the original image (Note: sometimes the first image displayed is scaled, use space to return automatically scaled images to their original scale). In array generation mode, the spacebar will stop the display of any images in progress and skip directly to the next image in the list. 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. Note that you can use the '/N<template>' command line parameter to change the name template for the files which are written. Alt-P Exactly like Alt-W, but uses the extension ".PCX" instead. This may come in handy for those of you using Deluxe Paint II Enhanced or any of Z-Soft's software. Alt-R Exactly like Alt-W, but uses the extension ".SC<c>" instead, where <c> is the screen resolution indicator as prescribed by RIX Software in Irvine, California. This may come in handy 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 file support, don't bother asking me, and please ask RIX to allow developers to support it. Arrows The arrow keys adjust the position of the lower right hand corner of the image rectangle. Using the arrow keys alone moves the lower right corner by two pixels at a time. Holding the shift key down while using the arrow keys moves it by 20 pixels at a time. If you manage to get the image messed up enough to start over, just hit the space bar and the image will redraw at it's default 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 with an odd screen size. Alt-Z Start 'zoom' sequence. WORKS ONLY WITH A MOUSE. Use 'Alt-Z' as follows when viewing an image: (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 desired rectangle. (5) Let go of the mouse button. The zoom function will preserve the current X to Y ratio for scaling in case you've adjusted it or used 'Alt-F' to fit the image to the screen. If you manage to zoom to the wrong place or mess things up beyond comprehension, just hit the space bar to redraw the image at it's default scale. Alt-F Fit image to screen. This function ATTEMPTS to rescale an image to fit into the full screen. It is useful for scaling images down. Depending on the dimensions of the image, this may not produce the desired results. If the aspect ratio of the graphics mode or the image is not recognizable by GDS, the image may end up very distorted. If this happens, use the spacebar to redraw the image at it's original 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. ',' & '.' Reduce/Increase color. This function can reduce a full color image to grey scale by using ',' to completely eliminate all color content. The image can further be reduced to a monochrome image by increasing the contrast to maximum (F8). This color level control compensates for the eye's responsiveness to red, green, and blue for minimal color distortion. 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. Shift-',' Reset color 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 /N<temp> Set template for filename generation /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. /N<template> This parameter sets the 'printf()' style template for filenames generated by GDS when array files are written. If you don't know what that means, DON'T MESS WITH IT! If you are familiar with printf(), then go ahead and change the template. The default string used by GDS for generating filenames is "GDS%03d", which creates a file such as "GDS042.GIF". /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 NOTE: If you have any problems with the video modes listed in GDS.CFG, or find discrepancies, please FAX or write me a note. I'm interested in supporting cards, although my time is limited. /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. GDS displays the horizontal resolution of the file as '-1'. 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. FAX or write me a note if you find a file that GDS will not display, but other viewers will. 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. Depending on the graphics mode that the image was stored on and the different graphics modes GDS supports for your video board, the aspect ratio of images can be way off. 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 (the 'Shift' key makes the arrows more powerful). To actually FIX these images, just manipulate the image until it fits nicely into the screen and write the image to a new file using 'Alt-W', 'Alt-P', or 'Alt-R'. 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. --> Corrected bug in array generation which could crash a system. The bug occurs when the individual array images were reduced to less than 1:32 of the original image size. This limitation was not protected against in prior versions of GDS. GDS is now capable of 1:64 image reduction and limits the size of array images to prevent users from reaching this limitation. --> Corrected many bugs in 'Alt-Z' zoom function during single image viewing. In prior versions, the zoom feature would inversely compensate for the aspect ratio of the screen. This version should handle the zoom feature as one would expect. --> Corrected nasty bug in two dimensional antialiasing when displaying zoomed areas. This bug would skew some lines in the display to the left of where they should have been drawn. The severity of the display problems depended on the level of zooming, the aspect ratio of the original image, and the position of the upper left zoom rectangle corner. NEW! Added 'READMAC' file format to list of supported formats. Readmac files (.MAC) can be read, but not yet written. Anybody out there want to write these files? Let me know. NEW! Added color control to single and array views. The overall color level in the palette can be adjusted with the ',' and '.' keys (normal case of '<' and '>'). To reset the color level, just hit Shift-',' or Shift-'.' ('<' or '>'). This feature, along with the other image palette options gives the user a surprising amount of control over problem images. NEW! Added page display compensation when generating arrays and using 'Alt-F' to fit an image to the display. In previous versions, high resolution portrait files would just be remapped to the entire screen. GDS now looks at the screen resolution and tries to figure out if it's a high resolution page display file. NEW! Increased EMS support for read-ahead buffering for slideshows. Slideshows now read images of any size while the current image is displayed. This facility will automatically buffer images, provided there is enough available system RAM and/or EMS to hold the images. NEW! Increased file table size to 2800 files. Yes, now you can have a slideshow which will last just under four hours (at 5 seconds between images) without repeating an image. Previous versions were limited to 2048 files. NEW! Added 'label' and 'border' preference buttons to array preview user interface. The 'Labels:' and 'Borders:' buttons may disappear from the text file display screen in future versions. NEW! Changed user interface for selecting array images. In earlier versions, it was necessary to set the 'View:Arrays' and then hit 'Enter' or click on the view button in order to start array generation. GDS now starts array generation immediately when the user selects 'Arrays of reduced images' from the 'View:' menu. There is no longer a 'View:Arrays' mode in GDS. NEW! Increased image reduction by 100%. Array images may now be displayed reduced down to 0.04% in 1024x768 graphics modes. With this increase, it is now possible to display 2304 reduced images on one 1024x768 screen. I encourage anyone who has that many images accessible to one machine to try this. At 150K per image, that's over 345 megabytes of GIF files. Unfortunately, even with antialiasing off, it should take an average of at least 5 seconds per image on a 33Mhz 80386 machine, and that works out to about 3 hours and 12 minutes. I want a copy of the result!