From: Andrew Apted <ajapted@netspace.net.au>
  To  : ggi-develop@eskimo.com
  Date: Fri, 17 Jul 1998 00:10:36 +1000

Re: New ggi_graphtype

Marcus writes:

>  > There is hardware like this, for example RGB 6:6:4 and (IIRC) RGB 5:7:4,
>  > so these need to be specifiable in the graphtype, especially since the
>  > graphtype is now the pixel-format as well.  Yes, applications will
>  > usually specify GT_AUTO for the subscheme, but they might *get back* an
>  > RGB 6:6:4 format, so the graphtype must differentiate it from any other
>  > 16 bit format (like RGB 5:6:5).
>  
>  Well, you might be right. In that case I'd say we have two alternatives:
>  a) Make the graphtype a struct
>  b) Remove the subscheme from the graphtype and put the information in
>     the mode-struct instead. 

I think we should stick to the subscheme idea.  The values of subscheme
can be arbitrary -- so long as they differentiate different modes at the
same scheme + depth.  This way, graphtype == pixel format ==
ggi_plb_common_setup == get/put buffer format.  Multible problems 
solved in one fell swoop.

>     The new members in ggi_mode would then be:
>     ggi_pixel red_mask,
>     ggi_pixel green_mask,
>     ggi_pixel blue_mask,
>     int reverse_endian,

There's no harm having that functionaly *in addition* to the graphtype,
maybe as an API call (e.g. ggiGetTrueColorMask(vis,*r,*g,*b)) or maybe
in some public structure -- although I doubt ggi_mode is the best place.

>     (For the 16-bit truecolor case reverse_bitness is replaced by the
>      masks. And for indexed modes... Well, what is "reverse bitorder"
>      on a indexed mode anyway? 

On modes < 8, "reverse bitorder" is the different between sp1a8lbl 
(low bit left) and sp1a8hbl (high bit left), for example.

>  On a sidenote - the size entry should go away from the ggi_mode
>  struct.

Agreed.  Monitor size seems like information that won't be available
with most targets anyway.  Maybe add a ggiGetMonitorSize() function to
libggimisc ?

Cheers,
_____________________________________________  ____
                                               \  /
  Andrew Apted   <andrew@ggi-project.org>       \/