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Text File | 1990-11-25 | 32.3 KB | 1,057 lines

//////// // ///// //// ////// // // // // // /////// ///// //// // // // // // ///// // // // // // // // // // // // // /////// // // //// ////// /////// //// // Version 5.1 Written By Bill Parquet and Dave Sharpless Copyright July, 1990 Introduction ------------------------------------------------------------- How often have you downloaded a GIF file from your favorite BBS only to discover you wasted maybe 15 minutes and 50,000 bytes of download credits on an array of dots that doesn't deserve to be called a picture, or had a "bad code in file" after the first 10 lines? Wouldn't it be better to see the picture as you are getting it? Just abort the transfer, saving your time and credits for something more worthwhile if you don't like it? If so, SHOWGIF is just the program for you! It is a TSR that quietly waits for the system to begin writing a GIF file. Once writing begins, SHOWGIF switches to the appropriate VGA or EGA video mode, and shows the picture as it is coming over. Unlike other view it while you get it setups, it works with nearly ALL protocols available. System Requirements ------------------------------------------------------------- For SHOWGIF to operate properly, your system must be equipped with an EGA, VGA, or Super-VGA video card. It also requires about 32k of memory (mostly for GIF decoding). Configuring ShowGIF ------------------------------------------------------------- The first step in operating ShowGIF is the setup. Configuring ShowGIF is a simple process. The first thing to do in this process is to select a setup file which best matches your card. Each of these files has the extension CNF. The first line of each of these files contains the name of card that it corresponds to. Pick out the one which best matches your video setup. Once you have selected the setup file for your system, run CSHOWGIF followed by the name of the name of the file that you have selected. For example "CSHOWGIF VGA.CFG" CSHOWGIF will print out the current setup and load in the new setup. It will inform you if you are using an unsupported bank switching method or if a resolution is unlikely. The final phase of the setup involves series of questions relating to how the operation of ShowGIF. Most of these options can be altered with the use of command line options, but are also available here for convenience. The first question refers to the message delay. It is the amount of time (in 0.054 second clock cycles) that the result of the view remains on the screen before returning to the original display. Normally it is 36, or about 2 seconds. You MUST enter a number here (the original setting given for reference). Next you're asked if you want to enable or disable stream and extension detection methods. If you hit enter for either of these, than the existing setting will be used. The implications of each will be discussed later. (NOTE: CSHOWGIF will not let you turn both methods off because ShowGIF would not have any way to detect a GIF file). Finally it asks if you wish ShowGIF to pause after the display. This is probably best left off. If enabled, ShowGIF will wait for a key before removing the picture. Like before, enter will keep the existing setting. The next changes are optional. CSHOWGIF will ask you if you wish to redefine the keys. Enter or 'N' will skip this phase. If you do wish to change the ShowGIF keys, hit 'Y'. It will then ask you that key to hit for aborting the view (normally BACKSPACE). Press the key that you wish to use. Next, it will ask you the key to use for blanking the screen (normally TAB). Press the key that you wish to use. Shift key sequences aren't recognized by either prompt, meaning CTRL C will be the same as SHIFT C, ALT C and C by itself. CSHOWGIF will not stop you from setting both functions to the same key, but you setting it as such will disable the screen blanker. NOTE: If you do reconfigure the keys, make sure they aren't keys that your protocol uses. These may included keys such as ESC, CTRL-C, CTRL-X. ShowGIF will trap these keys and prevent you from aborting your transfer. When you have finished, a reconfigured copy of ShowGIF will be written to disk. Operation Instructions ------------------------------------------------------------- Once you have ShowGIF configured, all you need do is type "SHOWGIF" before you load your favorite terminal program and it will be ready to use. Once you begin downloading a GIF file, or an archive that contains GIF files, ShowGIF will start, and begin displaying the data as it goes to disk. ShowGIF may not start immediately, as it must wait until it has collected enough information about the picture to begin drawing. It will usually "kick in" after the second Ymodem/Zmodem block. If anything goes wrong during the transfer, ShowGIF will abort and give you a message explaining what happened. If the transfer goes successfully, ShowGIF will finish with a "view successful" message. After you finishing your session in the terminal program and return to DOS, type "SHOWGIF /u" to remove ShowGIF from memory. Batch Files ------------------------------------------------------------- We recommend that you create that (if you haven't already) you create a batch file that loads ShowGIF, loads your terminal program, then unloads ShowGIF. This prevents ShowGIF from occupying memory any longer than it has to, and it helps to prevent the side effects mentioned later. If you plan to use ShowGIF in immediate mode, another batch file should be created. It should enact the setup for immediate viewing and pass the file you wish to view. There will be much less hassle with command-line switches and accidental installations. Here are a few sample batch files: @echo off showgif e:\modem\qmodem.42\qmodem showgif /u @echo off showgif /p:+ /d:1 %1 The first one installs ShowGIF, runs a terminal program, then uninstalls. The second uses ShowGIF's immediate mode to view a given GIF file with pausing on, then exits. ShowGIF function keys ------------------------------------------------------------- When active, ShowGIF allows you to perform two functions. (This includes both immediate mode and during file transfers) The first function is "Abort-View" It aborts the ShowGIF file viewer, but not the transfer itself. I don't see any practical use for this other than in immediate mode when you've "seen enough of the picture." During a download, you can just abort the transfer itself and ShowGIF will abort with it. The second function is an "on-demand" screen blanker. Its there to prevent those particularly embarrassing moments when your spouse walks into the room and happens to notice that you are downloading that new X-Rated picture. Despite that there is nothing on the screen, the download and view will progress normally. Any subsequent keypress will unblank the screen. The screen will automatically un-blank when ShowGif finishes (ie at end of transfer or if an error occurs). The default settings are backspace for abort view and tab for blank screen. You may change these with CSHOWGIF. Note that, Shift/Ctrl/Alt shift key combinations are NOT recognized! (ie Shift-X, Alt-X, Ctrl-X, and X are all the same). ALSO NOTE: do not choose combinations that your protocol uses for its functions. For example, if you're protocol uses Ctrl-C to abort the transfer, don't set blank- screen to C. How ShowGIF Works ------------------------------------------------------------- *** General Description *** DOS contains several services for opening, closing, writing to files. ShowGIF positions itself between the application program (usually your terminal program or external protocol) and the DOS. In this position it intercepts calls to DOS, checks to see if they are of any importance, then passes them along to DOS unaltered. This sounds dangerous and destructive but, in this situation, it is beneficial. ShowGIF can be in one of two states when it intercepts these DOS calls. The first state is where it monitors all the open and write calls. If one of these calls implies that a GIF file is going to disk, ShowGIF makes note of this file and switches to the second state. In the second state, ShowGIF monitors write and close calls. If the write is to go to aforementioned file, ShowGIF intercepts the data and decodes it to the screen. If it sees that the application is going to close the file one of two things happens. It will either print "View Successful" or "Transfer Aborted or File Incomplete" depending on whether the decoder finished and switched back to the monitoring state. All this happens unbeknownst to the file transfer software. The software assumes that it is performing normal opens, writes, and closes. The upshot of this is that downloads with ShowGIF and downloads without ShowGIF are identical, or nearly so. *** Modes of Detection *** In ShowGIF 5.1, unlike previous versions, there are two ways in which a GIF file can be detected. They are: - Detection by Filename-Extension - This is the original method of detecting GIF files. If a file opens with the GIF extension, ShowGIF will start and begin decoding. The advantages to this method are that it is very simple and quick. The disadvantages to it are that it will not detect a GIF file when the picture in circumstances such as when the protocol uses a temporary name than does not have the GIF extension (as in Procomm Plus and SeaLink) or when the GIF file is in an archive (a common practice among misinformed people). - Detection by File Streams - Detection by file streams works by monitoring the output to all the open files, and checking this output for the presence of the keyword "GIF87a." This will detect a GIF file with any name and even if its part of another file (such as stored in a ZIP file). Unfortunately, this method may slow down drive access (although not noticeably) and may cause it to start unnecessarily. (For instance, it would believe this text file is a GIF because of the header string listed above). Command Line Options ------------------------------------------------------------- /u : Uninstalls ShowGIF. This returns all the memory used by ShowGIF and restores the system vectors tapped by ShowGIF. The Uninstall routine was repaired somewhat, but if it still causes trouble, MARK & RELEASE can be used successfully. A word of warning to the wise: If you install ShowGIF and install another TSR, then uninstall ShowGIF, memory will become fragmented (not unlike fragmentation on your hard drive) and your computer will probably lock up the next time you load a program. /e+ /e- : Enables or Disables detection of GIF files by the extension of their filename. These switches can override the setting made during setup. /s+ /s- : Enables or Disables detection of GIF files by the contents of the file output streams. These switches can override the setting made during setup. /p+ /p- : Forces or prevents ShowGIF from waiting for a keystroke after displaying the picture. This allows you to admire the picture for a little bit after drawing is complete. This will override any setting made in setup. You may want to enable this feature for viewing GIFs in immediate mode: "SHOWGIF /p:+ KYM256.GIF" or if you use ShowGIF for viewing GIF files. /d:xx: Sets a delay for the result to remain on the screen after viewing is complete. xx may range from 1 to 255, and is proportional to the number of seconds (divide by 18.2) /b : Disable BIOS video trapping. I put BIOS trapping in on a bit of a whim and I'm not absolutely sure of the consequences of what I've done. Nothing should go wrong, BUT if something does I've included this switch. 'File': Displays a certain file then exits. (Immediate mode). You may wish to use the /p:+ switch with this command. An example would be "SHOWGIF BALLONS.GIF" [sic] in which showgif would merely display that picture then exit. /h : Displays a help screen listing all the commands (except /b) ShowGIF messages ------------------------------------------------------------- *** Run-Time messages *** "Bad Code In File" Usually means that the picture data is in some way garbled. For those interested, it means that ShowGIF encountered a Zev-Lempel code that exceeded the acceptable range. "Damaged parameter block" ShowGIF found that the screen resolution request was unreasonable (ie 320 ≤ x-resoution ≤ 1280 and 200 ≤ y-resolution ≤ 1024) or the local picture size is larger than the requested resolution. This usually indicates that the text 'GIF87a' was encountered in a text file. "Not a GIF file" A file with the GIF extension was created, but the first 6 characters don't match the GIF header I.D. Its possible that somebody renamed a file of a different type to GIF just to annoy you! "Incomplete picture" This message usually occurs when you abort the transfer, but it also might occur because the person who uploaded the picture aborted and the BBS didn't delete the file. The worst part is there is no way to detect these until they happen. "Transfer aborted or GIF incomplete" The defined abort key was pressed and ShowGIF has returned to protocol's text screen. "View Successful" The picture passed through ShowGIF without any flaws. *** Installation Messages *** "ShowGIF: Already Installed" ShowGIF is already ready to use and won't let you install it twice. "ShowGIF: /u requires that ShowGIF be installed" ShowGIF cannot find its resident portion. "ShowGIF: Cannot open immediate file" You've started ShowGIF with an immediate filename that it cannot locate. "ShowGIF: Both detection methods are disabled, aborting installation" You've attempted to run ShowGIF with no way to detect a GIF file, so it would just sit in memory uselessly. You must use /e:+ and/or /s:+ to provide a means for detection. "ShowGIF: Invalid switch" Use ShowGIF /h to list the valid switches. "ShowGIF: Uninstalled" This just informs you that ShowGIF has been successfully Uninstalled and memory freed. Quirks ------------------------------------------------------------- Most quirks are due to ShowGIF's sensitivity to the creation of a GIF file alone and not its origin. For instance, COPYing a GIF file around also will kick in the viewer. Answers to common questions ------------------------------------------------------------- I'm using showgif in immediate mode. The picture comes up quickly then disappears. Is there any way to make it pause at the end? Yes: Use the command line /p:+ or turn pausing on in the setup. Note that if you turn it on in the setup, you may want it off in regular use, or else the screen will pause at the end of a download! ------------------------------------------------------------ Why won't ShowGIF sense when I'm downloading a GIF file? **Procomm Plus users will experience the problem. Fortunately, ShowGIF 5.1 addresses this issue with stream detection. To use stream detection give /s:+ command line or the change the setup. What usually happens is that the terminal (or protocol driver) makes a temporary file of some sort to be renamed after the transfer. This file usually doesn't have the GIF extension. Stream detection looks at the file contents instead of the extension. ------------------------------------------------------------- Why does showgif wait a very long period of time before starting, and operate in widely spaced bursts? Users of **Telix's built in Zmodem may experience this problem. Telix's sending its output to disk in large bursts causes this problem. Since ShowGIF operates off these disk- writes (not modem accesses), your problem occurs. The best solution to this problem is to disable buffering. If you're using a hard drive to download, the write time for each block is negligible. If you cannot disable buffering, your other options are to use a different protocol or an external protocol driver, or just not let it get to you. ------------------------------------------------------------ Why does ShowGIF activate then deactivate with an incomplete message, then reactivate? **Qmodem users have this problem, as Qmodem opens then closes the file, then reopens it. Either disable extension detection (and enable stream detection) /e:-/s:+ or just ignore it. It is harmless. Why does a lockup often follow uninstallation of ShowGIF? The most probable cause of this is installing something on top of ShowGIF. Here is what happens, you install ShowGIF, then you (mistakenly) install another TSR. After you finish, you uninstall ShowGIF with the /u switch. Now there is a 32k unused 'hole' in your used memory. Next thing you know, a different program tries to fit 200k of data into that 32k hole. Since this data doesn't fit, it over-writes your TSR in memory. Nothing seems wrong until you try to activate this now nonexistent TSR... ------------------------------------------------------------ I have a few unusually sized pictures . . . . . .And ShowGIF won't view them because it looks at the GIF header and checks to see if the information is feasible. Horizontal resolution must be between 320 and 1024. Vertical resolution must be between 200 and 1024, among other things. I implemented this extended checking to protect the stream detection against text files that mention 'GIF87a' or the like. There is no solution to this problem. ------------------------------------------------------------- Why won't ShowGIF use the whole screen on my Video 7 Fastwrite? Try issuing the /b command line switch to disable Video Bios interception. This is the only case I can think of where this switch may become necessary. ------------------------------------------------------------ ShowGIF wraps the picture around several times in the middle of the screen or Showgif gets past the first quarter of the screen and locks up. Recheck which configuration file you are using. The plane switching method probably isn't correct, or you are using an unsupported plane switching technique. Valid techniques are "NONE" "TSENG" "VIDEO7" "TRIDENT" "PARADISE" "CHIPSNTECH" and "ATI." ------------------------------------------------------------- My monitor goes nuts when viewing certain large pictures. Your monitor may not handle the resolution that your card is using. Remove the highest resolution from your current configure file, and try again. What can I do about ShowGIF significantly slowing down my file transfer? Use a different protocol or a different driver. The one that you are currently using depends on completion of drive accesses before proceeding with the transfer. Since ShowGIF "slows down" these transfers, poorly constructed protocols may suffer. ------------------------------------------------------------ I'm concerned that ShowGIF will interfere with the transfer itself. There is no reason to worry about ShowGIF interfering with the transfers themselves. ShowGIF operates transparently with most protocols. The only noticeable effect (for the protocol) is that drive access will be noticeably slower (as ShowGIF is both "un-GIFfing" the data and writing it to the drive). If the protocol uses interrupt driven I/O properly, no loss of speed will occur. Because ShowGIF operates with the streams of data going to the disk, NOT the streams of data coming from the modem, protocol reliability is not affected. Update Information ------------------------------------------------------------- 1.0 α: First version of SHOWGIF <Not released> * Converted from a standalone gif decoder into a decoder/viewer then into a TSR. 1.0 ß: Several features added: <Not released> * Status report at the end of viewing (Not a gif, bad code, etc.) * Support for ATI, TSENG chipsets, separate versions of the program * Switch back normal video if d/l is aborted before viewer is aborted. * Squeezing pictures to fit 320x200 (MCGA version) 2.0 : Several problems fixed: <Beta Test> * Code parsing routine completely re-written for speed * Rest of the main loop translated into machine language * Lockup after "Picture is not a GIF" message resolved * Picture information put up while drawing * Stack frame is normalized after each picture -- no more lockup's after viewing 'too many' pictures * 500% overall increase in speed! (benchmark 20 seconds in 1.0 to 4 seconds in 2.0) 3.0 : Improvements made <Beta Test> * Support for EGA * X axis scaling for pictures larger than 320 MCGA,EGA 3.5 : Improvements made <First release> * One program can handle various video cards * Internal configuration for video hardware * Support for 10 more video cards 3.7 : Improvements made <Beta Test> * 16 color (EGA) modes supported in standard VGA configuration (640x350 and 640x480) * Offset picture difficulties corrected. 4.1 : Improvements made <Rare Second release> * User definable resolutions (compatible with VPIC) * Better judgement is used when choosing video modes. 4.1B : Cosmetic changes <Preferred second release> * Mistake in "VGA.CFG" corrected (oops!) * Thought I fixed the "text at the bottom of the screen problem" but it still didn't work. 5.0 : A hack Version 5.0 is NOT a valid release. If you have a version 5.0 it <MAY> have a virus and should be deleted IMMEDIATELY 5.1 : Many Improvements made <Third release> * Opening screen * EGA routines GREATLY improved -- 3x's improvement in speed * Initialization translated into ml (except EGA color selection) for compactness & control * Various sections carefully optimized for a 50% increase in speed for VGA. * EGA screen output GREATLY improved for about 250% improvement in speed overall. * Bug with viewing certain pictures which are interlaced/smashed in EGA mode corrected * File stream detection added. * Checks the GIF header for information feasibility. * Immediate mode GIF viewing. * Control over the delay after viewing. * Optional press a key pause after picture display. * Bios video functions disabled during view. (Note: if this causes problems, it can be disabled with the /b switch) * More extensive command line options. * Bug with uninstall corrected (I think!) * Problems with memory allocation fixed (Doesn't take any more memory then it really needs -- only about 30k) * Abort-view key made more responsive (though I don't really see a need for using it) * On-demand screen blanker added. * Ability to redefine the control keys. Shareware notice ------------------------------------------------------------- The registration fee for ShowGIF is $30. For this we will give you: 1) A registered ShowGIF on 5 1/4 floppy (unless otherwise specified) with Super-VGA support, and the lengthy title screen removed. 2) A lovely printed version of the documentation. 3) Notice of future updates. If you wish to contact me, Call The Henrietta Outhouse (216/965-5463) or my board (419/531-2693 9p-9a weekdays only) BILL PARQUET 30231 BATES RD. PERRYSBURG, OHIO 43551-3827 Software Credits ------------------------------------------------------------- I will give credit for all the software that I have mentioned throughout this document. **VPIC is a first rate picture file viewer (if you ignore all the bugs). 2.9 is the newest version at the time of this writing. VPIC may be obtained from: BOB MONTGOMERY 132 PARSONS RD LONGWOOD FL 32779 **GIF is a trademark of Compuserve, an H&R Block company. **Qmodem may be the best communications program in existence. 4.2 is the newest version at the time of this writing. Qmodem can be obtained from: THE FORBIN PROJECT, INC. POST OFFICE BOX 702 CEDAR FALLS, IA 50613 **Procomm Plus is a terminal package made by: DATASTORM TECHNOLOGIES, INC POST OFFICE BOX 1471 COLUMBIA, MO 65205 **Telix is terminal package made by: EXIS, INC POST OFFICE BOX 130 WEST HILL, ONTARIO M1E R4 **Mark & Release are TSR management programs and are copyrighted by Turbo-Power software: TURBO-POWER SOFTWARE POST OFFICE BOX 66747 SCOTTS VALLEY, CA 95066-0757 Kudos ------------------------------------------------------------- I'd like to think a few people, without which, ShowGIF would be far less complete. Dave Sharpless: For programming the plane switching routines, entering the large amount of card information in the first release. Writing the intro for release 4.1 and the intro for future release 5.5 or 6.0 (the intro is done, now all I have to do is write the program!) and urging that I charge a fee for this. John Sharpless: Sysop of the Henrietta Outhouse III, For bringing ShowGIF's success & distribution. ShowGIF would probably only be used by the three of us and a couple people in Toledo if it weren't for him. Thank you for using ShowGIF!