pstoraster/gdev8bcm.h

   1 /* Copyright (C) 1994 Aladdin Enterprises.  All rights reserved.
   2
   3   This file is part of GNU Ghostscript.
   4
   5   GNU Ghostscript is distributed in the hope that it will be useful, but
   6   WITHOUT ANY WARRANTY.  No author or distributor accepts responsibility
   7   to anyone for the consequences of using it or for whether it serves any
   8   particular purpose or works at all, unless he says so in writing.  Refer
   9   to the GNU General Public License for full details.
  10
  11   Everyone is granted permission to copy, modify and redistribute GNU
  12   Ghostscript, but only under the conditions described in the GNU General
  13   Public License.  A copy of this license is supposed to have been given
  14   to you along with GNU Ghostscript so you can know your rights and
  15   responsibilities.  It should be in a file named COPYING.  Among other
  16   things, the copyright notice and this notice must be preserved on all
  17   copies.
  18
  19   Aladdin Enterprises supports the work of the GNU Project, but is not
  20   affiliated with the Free Software Foundation or the GNU Project.  GNU
  21   Ghostscript, as distributed by Aladdin Enterprises, does not require any
  22   GNU software to build or run it.
  23 */
  24
  25 /*$Id$ */
  26 /* Requires gxdevice.h (for gx_color_value) */
  27
  28 #ifndef gdev8bcm_INCLUDED
  29 #  define gdev8bcm_INCLUDED
  30
  31 /*
  32  * The MS-DOS, MS Windows, and X Windows drivers all use (at least on
  33  * some platforms) an 8-bit color map in which some fraction is reserved
  34  * for a pre-allocated cube and some or all of the remainder is
  35  * allocated dynamically.  Since looking up colors in this map can be
  36  * a major performance bottleneck, we provide an efficient implementation
  37  * that can be shared among drivers.
  38  *
  39  * As a performance compromise, we only look up the top 5 bits of the
  40  * RGB value in the color map.  This compromises color quality very little,
  41  * and allows substantial optimizations.
  42  */
  43
  44 #define gx_8bit_map_size 323
  45 #define gx_8bit_map_spreader 123        /* approx. 323 - (1.618 * 323) */
  46 typedef struct gx_8bit_map_entry_s {
  47     ushort rgb;                 /* key = 0rrrrrgggggbbbbb */
  48 #define gx_8bit_no_rgb ((ushort)0xffff)
  49 #define gx_8bit_rgb_key(r, g, b)\
  50   (((r >> (gx_color_value_bits - 5)) << 10) +\
  51    ((g >> (gx_color_value_bits - 5)) << 5) +\
  52    (b >> (gx_color_value_bits - 5)))
  53     short index;                /* value */
  54 } gx_8bit_map_entry;
  55 typedef struct gx_8bit_color_map_s {
  56     int count;                  /* # of occupied entries */
  57     int max_count;              /* max # of occupied entries */
  58     gx_8bit_map_entry map[gx_8bit_map_size + 1];
  59 } gx_8bit_color_map;
  60
  61 /* Initialize an 8-bit color map. */
  62 void gx_8bit_map_init(P2(gx_8bit_color_map *, int));
  63
  64 /* Look up a color in an 8-bit color map. */
  65 /* Return -1 if not found. */
  66 int gx_8bit_map_rgb_color(P4(const gx_8bit_color_map *, gx_color_value,
  67                              gx_color_value, gx_color_value));
  68
  69 /* Test whether an 8-bit color map has room for more entries. */
  70 #define gx_8bit_map_is_full(pcm)\
  71   ((pcm)->count == (pcm)->max_count)
  72
  73 /* Add a color to an 8-bit color map. */
  74 /* Return -1 if the map is full. */
  75 int gx_8bit_add_rgb_color(P4(gx_8bit_color_map *, gx_color_value,
  76                              gx_color_value, gx_color_value));
  77
  78 #endif /* gdev8bcm_INCLUDED */