From: Steve Cheng <elmert@ipoline.com>
  To  : ggi-develop@eskimo.com
  Date: Wed, 12 Aug 1998 14:45:20 -0400 (EDT)

Re: LibGGI colormapping

On Wed, 12 Aug 1998, Andrew Apted wrote:

> The colormapping inside of LibGGI has always been dodgy, and now's a
> great time to clean that up.  [BTW, I was rather surprised to see
> default/linear-*/color.c vanish right before my eyes :)]
> 
> Here's the plan:  The ggi_visual structure has a "ggi_color *palette"
> field which is non-NULL for GT_PALETTE modes, and contains the current
> palette.  
> 
> Then, we have a "generic-color" sub-library which implements
> ggiMapColor() and ggiUnmapPixel() for GT_PALETTE modes (using
> vis->palette) and GT_TRUECOLOR modes (using vis->pixelformat) and
> GT_GREYSCALE modes (using a simple formula).  It also implements
> ggiPackColors() and ggiUnpackPixels().

Also ggiGetPalette().
Targets setting indexed modes would load the current palette (e.g. X,
minimize flashing), or set it to RGB233 (where it does not matter, e.g.
svgalib).

> Although this could be done in generic-stubs, separating the color
> mapping stuff from the drawing stuff is cleaner IMHO,  We could even
> rename "generic-stubs" to "generic-draw" ... that would be nice.
> 
> What do you think ?  Again I'm happy to implement it.

Good idea.  I always wanted to make the color stuff in targets to be common
code, but this is much better.

--
Steve Cheng               

email: steve@ggi-project.org   
www: <http://shell.ipoline.com/~elmert/>;