PCX.svobject

  © 1993-94 by Andreas R. Kleinert.

  FREEWARE. All rights reserved.

  Version      : 2.6
  Release Date : 02.04.1994


  Description
  ~~~~~~~~~~~
  PCX.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-/ChunkyPixel-Support.

  It supports reading and writing of PCX Files.
  In detail these are :

  Reading :

   - PCX V2.5  upto 16 Colors (supports 4/8 color EGA/VGA palette)
   - PCX V2.8a upto 16 Colors (supports 4/8 color EGA/VGA palette)
   - PCX V2.8b
   - PCX V3.00 upto 256 Colors

  Writing :

   Depending on the Colordepth of the source - no matter, which WriteSubType
   has been specified - the following is written :

   Source Colors    Version	 Type		   Destination Colors

    2 ..  16	    PCX V2.8a	 planar bitmap	    16
   32 .. 256	    PCX V3.00	 chunky pixel	   256


  Remarks
  ~~~~~~~
  - Why writing only 16/256 Color files ?

    When loading 4 Color PCX files, some programs might expect a CGA style
    color palette, while we only write EGA/VGA palettes. For 8 Color graphics
    it is not clear how they should be handled.
    Also, most programs do not support 32 .. 128 Color graphics, perhaps
    because it is not clear, how the colormap has to be stored :
    all at the end of the file or one hunk in the header and only the rest
    at the end of the file ?

    So why should PCX.svobject support things, which are not defined as
    clear as they should be ?

  - Then, why reading 4/8 Color files nevertheless ?

    Because PCX.svobject wrote them - this was my fault - before I fixed
    this bug. So it still reads them, but no longer writes them.


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


  History
  ~~~~~~~
  V2.6 (02.04.1994) :

   - improved speed of RLE decoding routines


  V2.5 (27.03.1994) :

   - removed internal SVDriver-Replacement, so that we now are really
     dependent on external SVDrivers in libs:svdrivers.
     This saves about 1600 Bytes diskspace and reduces redundancy.
   - replaced SAS/C's sprintf()-routine with own, RawDoFmt()-based one.
     This saves again about 1800 Bytes.
   - now using Utility-Library for integer operations (activated
     SAS/C's UTILLIB option) : this increases 68000-codesize a little
     bit, but increases speed on 68020+ systems
     (should also decrease codesize, but does not ...)


  V2.4 (25.03.1994) :

   - slightly improved internal BitMap-to-BitMap routine


  V2.3 (18.03.1994) :

   - removed some dead code (not compiled nor linked ?!)


  V2.2 (17.03.1994) :

   - fixed "large memory usage" bug in internal ECS-ChunkyPixel routine
   - added several security checks (zero-pointers)


  V2.1 (09.03.1994) :

   - now with SVDriver-Support. Not yet necessarily needed.
   - improved internal "Chunky Pixel to BitMap" (8 Bit) Routine
   - writing routine(s) :
      - added code for writing 256 Color graphics (chunky pixel)
      - 2, 4, 8, 32, 64 or 128 Colors are expanded to either
	16 or 256 Colors before writing
      - 16 Colors now written as V2.8a, also fixed some small bugs
      - increased speed for writing 16 Colors
      - fixed bug in setting map for 16 Colors
	(same as in reading routine, which was fixed in V1.2)
   - fixed small bug in memory management routines
   - internal routines : AUTOSCROLL now really works with big-sized Screens
   - fixed several little bugs


  V1.3 (24.01.1993) :

   - fixed bug with setting ColorMap under V37/V38


  V1.2 (02.01.1993) :

   - fixed "wrong colors" bug
   - improved speed


  V1.1 (19.12.1993) :

   - first version


  Literature
  ~~~~~~~~~~
  [1] "Supercharged Bitmapped Graphics", Steve Rimmer, Windcrest/McGraw-Hill,
       © 1992 by Windcrest Books (registered Trademark of TAB Books).
       ISBN 0-8306-3788-5
  [2] "Amiga Magazin", Issue 2/1992, Markt & Technik Verlag AG
  [3] "DOS Extra", Issue 4/1993, DMV-Verlag


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