Re: Lout Backends

[Jeff Kingston]

On Sun, 28 Oct 2001 22:21:32 -0500, Ludovic Courtès wrote:
  > 
  > > No, but if you snoop around in z49.c you will find comments on most of
  > > the routines that should shed some light.  Beyond that you will have to
  > > read the code and reverse engineer.
  > 
  > All right, I was just hoping I could find some better documentation. ;)     
  > Also, the Plain Text backend doesn't help much regarding hpos/vpos and
  > color numbering.
  > Where should I look for help on this topics?

The numbers are coordinates in a system in which 20 is a distance of
one point.  Either the origin is at the top left of the page and
y values increase as you go down, or else it's at the bottom left of
the page and y values increase as you go up, depending on just where
in the Lout source you are.  The coordinate system changes inside
@Scale and @Rotate commands.

Reverse engineering tables and paragraphs off coordinates would be
a horrible job.  Don't do it.

The colour numbers are not associated with particular colours
in a fixed way; rather, Lout assigns a colour number to every distinct
value of the left parameter of @SetColour as it arrives, and prints this
left parameter into the PostScript output whenever the colour changes.
Lout does not understand what the colours mean at all.

The only way to understand this further is to read the code.

Jeff Kingston