Targa.svobject

  © 1994 by Andreas R. Kleinert.

  FREEWARE. All rights reserved.

  Version      : 2.3
  Release Date : 12.06.1994


  Requirements
  ~~~~~~~~~~~~
  - OS V2.04+ (V37)+ and its libraries
  - superviewsupport.library V3+


  Description
  ~~~~~~~~~~~
  Targa.svobject is an external Library-Module for the superview.library V2+.

  It contains SVDriver-Support for the superview.library V3+, and
  needs any SVDriver with Bitplane-Support.

  It supports reading of TGA (Truevision Targa) Files.
  In detail these are :

  Reading :

   - monochrome Targa-Files (1 Bit, planar)
   - Targa with 256 Colors (8 Bit)
     (files without ColorMap are displayed in grey-scales)
   - Targa 24 Bit-Files

  Writing :

   Depending on the Colordepth of the source the following is written :

   Source Colors    Type                           Destination Colors

    2 .. 256        Uncompressed chunky pixel         256
    (24 Bit)        Uncompressed BGR                 (24 Bit)


  Remarks
  ~~~~~~~
   - Currently files with Colorbits other than 1, 8 or 24 (16, 32)
     are not supported yet.
   - ColorMaps have to be of type "3-Byte RGB".
   - RLE-encoded files are rejected yet.
   - The flags for "mirroring" Images vertically and/or horizontally
     are nut fully interpreted yet, nevertheless they are checked and
     reported via SVL_FileInfoRequest().
     If the VERTINV flag is not set, the picture will be assumed to
     be written as "from bottom to top", otherwise as "from top to
     bottom". Some programs do not set these flags right, when writing,
     so that you might get just the opposite result as expected.
     The HORIZINV flag is currently ignored : when reading such a picture
     as usual, you'd get a mirrored image. But this flags is also set
     wrong sometimes ...


  Author
  ~~~~~~
  Andreas R. Kleinert
  Grube Hohe Grethe 23
  D-57074 Siegen
  Germany


  History
  ~~~~~~~
  V2.3 (12.06.1994) :

   - now also writes Targa files (all input converted to either 8 or 24 Bit)
   - now also reads monochrome pictures with pixelbits value of 1 (planar)
   - files with no VERTINV set are now converted (top becomes bottom)
   - changed way of file-recognition : files with unknown flags are now
     read as if theses flags would not have been set. This may cause
     problems with files, which depend on correct interpretation of those
     flags, but often they are written wrong, so that this might have
     caused files to be rejected. Now we check an other Byte-combination
     for plausibility reasons.


  V2.2 (22.05.1994) :

   - removed some unused debugging code : this was accidentally called
     always, when a picture has been loaded.
     This did not crash the program, but always caused a requester, which
     had to be confirmed by the User.


  V2.1 (22.05.1994) :

   - first version


  Literature
  ~~~~~~~~~~
  [1] "Bitmapped Graphics", 2nd Edition, Steve Rimmer, Windcrest/McGraw-Hill,
       © 1993 by Windcrest Books (registered Trademark of TAB Books).
       ISBN 0-8306-4209-9
  [2] "Supercharged Bitmapped Graphics", Steve Rimmer, Windcrest/McGraw-Hill,
       © 1992 by Windcrest Books (registered Trademark of TAB Books).
       ISBN 0-8306-3788-5
  [3] "Das Handbuch der Grafikformate", Klaus Holtorf, © 1994 Franzis-Verlag
       GmbH, München
       ISBN 3-7723-6392-X
  [4] (there was more literature, but I didn't actually need it ;-)


  Copyrights
  ~~~~~~~~~~
  Some of the mentioned names or products above may be copyrighted by
  companies or trademarks of companies.