/* Copyright (C) 1995, 1996 Aladdin Enterprises.  All rights reserved.
  
  This file is part of GNU Ghostscript.
  
  GNU Ghostscript is distributed in the hope that it will be useful, but
  WITHOUT ANY WARRANTY.  No author or distributor accepts responsibility
  to anyone for the consequences of using it or for whether it serves any
  particular purpose or works at all, unless he says so in writing.  Refer
  to the GNU General Public License for full details.
  
  Everyone is granted permission to copy, modify and redistribute GNU
  Ghostscript, but only under the conditions described in the GNU General
  Public License.  A copy of this license is supposed to have been given
  to you along with GNU Ghostscript so you can know your rights and
  responsibilities.  It should be in a file named COPYING.  Among other
  things, the copyright notice and this notice must be preserved on all
  copies.
*/

/*$RCSfile: gdevstc3.c,v $ $Revision: 1.2.2.1 $*/
/* Epson Stylus-Color Printer-Driver */

/***
     This file holds the sample-implementation of a RGB-algorithm for
     the stcolor-driver. It is available via

          gs -sDEVICE=stcolor -sDithering=gsrgb ...

     Actually this is no dithering-algorithm, it lets ghostscript do the job.
     This achieved, by requesting BYTE-Values between 0 and 1 to be delivered,
     which causes a depth of 1-Bit by default.

 ***/

/*
 * gdevstc.h holds all the includes and the driver-specific definitions, so
 * it is the only include you need. To add a new algorthim, STC_MODI in
 * gdevstc.h should be extended. (see the instructions there)
 */

#include "gdevstc.h"

/*
 * the routine required.
 */

/*ARGSUSED*/
int 
stc_gsrgb(stcolor_device *sdev,int npixel,byte *ip,byte *buf,byte *out)
{

   int   error = 0;

/*
 * There are basically 3 Types of calls:
 * npixel < 0    => initialize buf, if this is required
 *                  (happens only if requested)
 * npixel > 0    => process next scanline, if the flag STC_WHITE is set, then
 *                  in == NULL signals, that the basic-driver has decided
 *                  that this scanline is white. (Useful for really dithering
 *                  drivers)
 */

/* ============================================================= */
   if(npixel > 0) {  /* npixel >  0 -> scanline-processing       */
/* ============================================================= */

      int p;

/*
 *    simply merge the color-values into a single byte 
 *    (RED, GREEN, BLUE are defined in gdevstc.h)
 */
      for(p = 0; p < npixel; ++p,++out) { /* loop over pixels */

         *out = 0;
         if(*ip++) *out |= RED;
         if(*ip++) *out |= GREEN;
         if(*ip++) *out |= BLUE;

      }                                   /* loop over pixels */

/* ============================================================= */
   } else {          /* npixel <= 0 -> initialisation            */
/* ============================================================= */
/*
 * besides buffer-Initialisation, one may check the parameters in
 * the algorithm-table of the driver.
 */

/*    we didn't check for the white-calls above, so they would cause errors */
      if(sdev->stc.dither->flags & STC_WHITE)              error = -1;

/*    if we're not setup for bytes, this is an error too */
      if((sdev->stc.dither->flags & STC_TYPE) != STC_BYTE) error = -2;

/*    and rgb-mode is the only supported mode */
      if(sdev->color_info.num_components != 3)             error = -3;

/*    we can't deal with ghostscript-data directly. */
      if(sdev->stc.dither->flags & STC_DIRECT)             error = -4;

/* ============================================================= */
   } /* scanline-processing or initialisation */
/* ============================================================= */

   return error;
}
