gtk/gdk/x11/gdkcc-x11.c

/* GDK - The GIMP Drawing Kit
 * Copyright (C) 1995-1997 Peter Mattis, Spencer Kimball and Josh MacDonald
 *
 * This library is free software; you can redistribute it and/or
 * modify it under the terms of the GNU Library General Public
 * License as published by the Free Software Foundation; either
 * version 2 of the License, or (at your option) any later version.
 *
 * This library is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
 * Library General Public License for more details.
 *
 * You should have received a copy of the GNU Library General Public
 * License along with this library; if not, write to the
 * Free Software Foundation, Inc., 59 Temple Place - Suite 330,
 * Boston, MA 02111-1307, USA.
 */

/* Color Context module
 * Copyright 1994,1995 John L. Cwikla
 * Copyright (C) 1997 by Ripley Software Development
 * Copyright (C) 1997 by Federico Mena (port to Gtk/Gdk)
 */

/* Copyright 1994,1995 John L. Cwikla
 *
 * Permission to use, copy, modify, distribute, and sell this software
 * and its documentation for any purpose is hereby granted without fee,
 * provided that the above copyright notice appears in all copies and that
 * both that copyright notice and this permission notice appear in
 * supporting documentation, and that the name of John L. Cwikla or
 * Wolfram Research, Inc not be used in advertising or publicity
 * pertaining to distribution of the software without specific, written
 * prior permission.  John L. Cwikla and Wolfram Research, Inc make no
 * representations about the suitability of this software for any
 * purpose.  It is provided "as is" without express or implied warranty.
 *
 * John L. Cwikla and Wolfram Research, Inc disclaim all warranties with
 * regard to this software, including all implied warranties of
 * merchantability and fitness, in no event shall John L. Cwikla or
 * Wolfram Research, Inc be liable for any special, indirect or
 * consequential damages or any damages whatsoever resulting from loss of
 * use, data or profits, whether in an action of contract, negligence or
 * other tortious action, arising out of or in connection with the use or
 * performance of this software.
 *
 * Author:
 *  John L. Cwikla
 *  X Programmer
 *  Wolfram Research Inc.
 *
 *  cwikla@wri.com
 */

/*
 * Modified by the GTK+ Team and others 1997-1999.  See the AUTHORS
 * file for a list of people on the GTK+ Team.  See the ChangeLog
 * files for a list of changes.  These files are distributed with
 * GTK+ at ftp://ftp.gtk.org/pub/gtk/. 
 */

#include <X11/Xlib.h>
#include <stdlib.h>
#include <string.h>
#include "gdk.h"
#include "gdkprivate.h"
#include "gdkx.h"


#define MAX_IMAGE_COLORS 256


static guint
hash_color (gconstpointer key)
{
  const GdkColor *color = key;
  
  return (color->red * 33023 + color->green * 30013 + color->blue * 27011);
}

static gint
compare_colors (gconstpointer a,
		gconstpointer b)
{
  const GdkColor *aa = a;
  const GdkColor *bb = b;
  
  return ((aa->red == bb->red) && (aa->green == bb->green) && (aa->blue == bb->blue));
}

static void
free_hash_entry (gpointer key,
		 gpointer value,
		 gpointer user_data)
{
  g_free (key); /* key and value are the same GdkColor */
}

static int
pixel_sort (const void *a, const void *b)
{
  return ((GdkColor *) a)->pixel - ((GdkColor *) b)->pixel;
}

/* XXX: This function does an XQueryColors() the hard way, because there is
 * no corresponding function in Gdk.
 */

static void
my_x_query_colors (GdkColormap *colormap,
		   GdkColor    *colors,
		   gint         ncolors)
{
  XColor *xcolors;
  gint    i;
  
  xcolors = g_new (XColor, ncolors);
  for (i = 0; i < ncolors; i++)
    xcolors[i].pixel = colors[i].pixel;
  
  XQueryColors (gdk_display, GDK_COLORMAP_XCOLORMAP (colormap), xcolors, ncolors);
  
  for (i = 0; i < ncolors; i++)
    {
      colors[i].red   = xcolors[i].red;
      colors[i].green = xcolors[i].green;
      colors[i].blue  = xcolors[i].blue;
    }
  
  g_free (xcolors);
}

static void
query_colors (GdkColorContext *cc)
{
  gint i;
  GdkColorContextPrivate *ccp = (GdkColorContextPrivate *) cc;
  cc->cmap = g_new (GdkColor, cc->num_colors);
  
  for (i = 0; i < cc->num_colors; i++)
    cc->cmap[i].pixel = cc->clut ? cc->clut[i] : ccp->std_cmap.base_pixel + i;
  
  my_x_query_colors (cc->colormap, cc->cmap, cc->num_colors);
  
  qsort (cc->cmap, cc->num_colors, sizeof (GdkColor), pixel_sort);
}

static void
init_bw (GdkColorContext *cc)
{
  GdkColor color;
  
  g_warning ("init_bw: failed to allocate colors, falling back to black and white");
  
  cc->mode = GDK_CC_MODE_BW;
  
  color.red = color.green = color.blue = 0;
  
  if (!gdk_color_alloc (cc->colormap, &color))
    cc->black_pixel = 0;
  else
    cc->black_pixel = color.pixel;
  
  color.red = color.green = color.blue = 0xffff;
  
  if (!gdk_color_alloc (cc->colormap, &color))
    cc->white_pixel = cc->black_pixel ? 0 : 1;
  else
    cc->white_pixel = color.pixel;
  
  cc->num_colors = 2;
}

static void
init_gray (GdkColorContext *cc)
{
  GdkColorContextPrivate *ccp = (GdkColorContextPrivate *) cc;
  GdkColor *clrs, *cstart;
  gint i;
  gdouble dinc;
  
  cc->num_colors = GDK_VISUAL_XVISUAL (cc->visual)->map_entries;
  
  cc->clut = g_new (gulong, cc->num_colors);
  cstart = g_new (GdkColor, cc->num_colors);
  
 retrygray:
  
  dinc = 65535.0 / (cc->num_colors - 1);
  
  clrs = cstart;
  
  for (i = 0; i < cc->num_colors; i++)
    {
      clrs->red = clrs->green = clrs->blue = dinc * i;
      
      if (!gdk_color_alloc (cc->colormap, clrs))
	{
	  gdk_colors_free (cc->colormap, cc->clut, i, 0);
	  
	  cc->num_colors /= 2;
	  
	  if (cc->num_colors > 1)
	    goto retrygray;
	  else
	    {
	      g_free (cc->clut);
	      cc->clut = NULL;
	      init_bw (cc);
	      g_free (cstart);
	      return;
	    }
	}
      
      cc->clut[i] = clrs++->pixel;
    }
  
  g_free (cstart);
  
  /* XXX: is this the right thing to do? */
  ccp->std_cmap.colormap = GDK_COLORMAP_XCOLORMAP (cc->colormap);
  ccp->std_cmap.base_pixel = 0;
  ccp->std_cmap.red_max = cc->num_colors - 1;
  ccp->std_cmap.green_max = 0;
  ccp->std_cmap.blue_max = 0;
  ccp->std_cmap.red_mult = 1;
  ccp->std_cmap.green_mult = 0;
  ccp->std_cmap.blue_mult = 0;
  
  cc->white_pixel = WhitePixel (ccp->xdisplay, gdk_screen);
  cc->black_pixel = BlackPixel (ccp->xdisplay, gdk_screen);
  
  query_colors (cc);
  
  cc->mode = GDK_CC_MODE_MY_GRAY;
}

static void
init_color (GdkColorContext *cc)
{
  GdkColorContextPrivate *ccp = (GdkColorContextPrivate *) cc;
  gint cubeval;
  
  cubeval = 1;
  while ((cubeval * cubeval * cubeval) < GDK_VISUAL_XVISUAL (cc->visual)->map_entries)
    cubeval++;
  cubeval--;
  
  cc->num_colors = cubeval * cubeval * cubeval;
  
  ccp->std_cmap.red_max    = cubeval - 1;
  ccp->std_cmap.green_max  = cubeval - 1;
  ccp->std_cmap.blue_max   = cubeval - 1;
  ccp->std_cmap.red_mult   = cubeval * cubeval;
  ccp->std_cmap.green_mult = cubeval;
  ccp->std_cmap.blue_mult  = 1;
  ccp->std_cmap.base_pixel = 0;
  
  cc->white_pixel = WhitePixel (ccp->xdisplay, gdk_screen);
  cc->black_pixel = BlackPixel (ccp->xdisplay, gdk_screen);
  cc->num_colors = DisplayCells (ccp->xdisplay, gdk_screen);
  
  /* a CLUT for storing allocated pixel indices */
  
  cc->max_colors = cc->num_colors;
  cc->clut = g_new (gulong, cc->max_colors);
  
  for (cubeval = 0; cubeval < cc->max_colors; cubeval++)
    cc->clut[cubeval] = cubeval;
  
  query_colors (cc);
  
  cc->mode = GDK_CC_MODE_STD_CMAP;
}


static void
init_true_color (GdkColorContext *cc)
{
  GdkColorContextPrivate *ccp = (GdkColorContextPrivate *) cc;
  gulong rmask, gmask, bmask;
  
  cc->mode = GDK_CC_MODE_TRUE;
  
  /* Red */
  
  rmask = cc->masks.red = cc->visual->red_mask;
  
  cc->shifts.red = 0;
  cc->bits.red = 0;
  
  while (!(rmask & 1))
    {
      rmask >>= 1;
      cc->shifts.red++;
    }
  
  while (rmask & 1)
    {
      rmask >>= 1;
      cc->bits.red++;
    }
  
  /* Green */
  
  gmask = cc->masks.green = cc->visual->green_mask;
  
  cc->shifts.green = 0;
  cc->bits.green = 0;
  
  while (!(gmask & 1))
    {
      gmask >>= 1;
      cc->shifts.green++;
    }
  
  while (gmask & 1)
    {
      gmask >>= 1;
      cc->bits.green++;
    }
  
  /* Blue */
  
  bmask = cc->masks.blue = cc->visual->blue_mask;
  
  cc->shifts.blue = 0;
  cc->bits.blue = 0;
  
  while (!(bmask & 1))
    {
      bmask >>= 1;
      cc->shifts.blue++;
    }
  
  while (bmask & 1)
    {
      bmask >>= 1;
      cc->bits.blue++;
    }
  
  cc->num_colors = (cc->visual->red_mask | cc->visual->green_mask | cc->visual->blue_mask) + 1;
  cc->white_pixel = WhitePixel (ccp->xdisplay, gdk_screen);
  cc->black_pixel = BlackPixel (ccp->xdisplay, gdk_screen);
}

static void
init_direct_color (GdkColorContext *cc)
{
  gint n, count;
  GdkColor *clrs, *cstart;
  gulong rval, gval, bval;
  gulong *rtable;
  gulong *gtable;
  gulong *btable;
  gdouble dinc;
  
  init_true_color (cc); /* for shift stuff */
  
  rval = cc->visual->red_mask >> cc->shifts.red;
  gval = cc->visual->green_mask >> cc->shifts.green;
  bval = cc->visual->blue_mask >> cc->shifts.blue;
  
  rtable = g_new (gulong, rval + 1);
  gtable = g_new (gulong, gval + 1);
  btable = g_new (gulong, bval + 1);
  
  cc->max_entry = MAX (rval, gval);
  cc->max_entry = MAX (cc->max_entry, bval);
  
  cstart = g_new (GdkColor, cc->max_entry + 1);
  cc->clut = g_new (gulong, cc->max_entry + 1);
  
 retrydirect:
  
  for (n = 0; n < rval; n++)
    rtable[n] = rval ? (65535.0 / rval * n) : 0;
  
  for (n = 0; n < gval; n++)
    gtable[n] = gval ? (65535.0 / gval * n) : 0;
  
  for (n = 0; n < bval; n++)
    btable[n] = bval ? (65535.0 / bval * n) : 0;
  
  cc->max_entry = MAX (rval, gval);
  cc->max_entry = MAX (cc->max_entry, bval);
  
  count = 0;
  clrs = cstart;
  cc->num_colors = (rval + 1) * (gval + 1) * (bval + 1);
  
  for (n = 0; n < cc->max_entry; n++)
    {
      dinc = (double) n / cc->max_entry;
      
      clrs->red   = rtable[(int) (dinc * rval)];
      clrs->green = gtable[(int) (dinc * gval)];
      clrs->blue  = btable[(int) (dinc * bval)];
      
      if (gdk_color_alloc (cc->colormap, clrs))
	{
	  cc->clut[count++] = clrs->pixel;
	  clrs++;
	}
      else
	{
	  gdk_colors_free (cc->colormap, cc->clut, count, 0);
	  
	  rval >>= 1;
	  gval >>= 1;
	  bval >>= 1;
	  
	  cc->masks.red   = (cc->masks.red >> 1) & cc->visual->red_mask;
	  cc->masks.green = (cc->masks.green >> 1) & cc->visual->green_mask;
	  cc->masks.blue  = (cc->masks.blue >> 1) & cc->visual->blue_mask;
	  
	  cc->shifts.red++;
	  cc->shifts.green++;
	  cc->shifts.blue++;
	  
	  cc->bits.red--;
	  cc->bits.green--;
	  cc->bits.blue--;
	  
	  cc->num_colors = (rval + 1) * (gval + 1) * (bval + 1);
	  
	  if (cc->num_colors >1)
	    goto retrydirect;
	  else
	    {
	      g_free (cc->clut);
	      cc->clut = NULL;
	      init_bw (cc);
	      break;
	    }
	}
    }
  
  /* Update allocated color count; original num_colors is max_entry, which
   * is not necessarily the same as the really allocated number of colors.
   */
  
  cc->num_colors = count;
  
  g_free (rtable);
  g_free (gtable);
  g_free (btable);
  g_free (cstart);
}

static void
init_palette (GdkColorContext *cc)
{
  /* restore correct mode for this cc */
  
  switch (cc->visual->type)
    {
    case GDK_VISUAL_STATIC_GRAY:
    case GDK_VISUAL_GRAYSCALE:
      if (GDK_VISUAL_XVISUAL (cc->visual)->map_entries == 2)
	cc->mode = GDK_CC_MODE_BW;
      else
	cc->mode = GDK_CC_MODE_MY_GRAY;
      break;
      
    case GDK_VISUAL_TRUE_COLOR:
    case GDK_VISUAL_DIRECT_COLOR:
      cc->mode = GDK_CC_MODE_TRUE;
      break;
      
    case GDK_VISUAL_STATIC_COLOR:
    case GDK_VISUAL_PSEUDO_COLOR:
      cc->mode = GDK_CC_MODE_STD_CMAP;
      break;
      
    default:
      cc->mode = GDK_CC_MODE_UNDEFINED;
      break;
    }
  
  /* previous palette */
  
  if (cc->num_palette)
    g_free (cc->palette);
  
  if (cc->fast_dither)
    g_free (cc->fast_dither);
  
  /* clear hash table if present */
  
  if (cc->color_hash)
    {
      g_hash_table_foreach (cc->color_hash,
			    free_hash_entry,
			    NULL);
      g_hash_table_destroy (cc->color_hash);
      cc->color_hash = NULL;
    }
  
  cc->palette = NULL;
  cc->num_palette = 0;
  cc->fast_dither = NULL;
}

GdkColorContext *
gdk_color_context_new (GdkVisual   *visual,
		       GdkColormap *colormap)
{
  GdkColorContextPrivate *ccp;
  gint use_private_colormap = FALSE; /* XXX: maybe restore full functionality later? */
  GdkColorContext *cc;
  gint retry_count;
  GdkColormap *default_colormap;
  
  g_assert (visual != NULL);
  g_assert (colormap != NULL);
  
  ccp = g_new (GdkColorContextPrivate, 1);
  cc = (GdkColorContext *) ccp;
  ccp->xdisplay = gdk_display;
  cc->visual = visual;
  cc->colormap = colormap;
  cc->clut = NULL;
  cc->cmap = NULL;
  cc->mode = GDK_CC_MODE_UNDEFINED;
  cc->need_to_free_colormap = FALSE;
  
  cc->color_hash = NULL;
  cc->palette = NULL;
  cc->num_palette = 0;
  cc->fast_dither = NULL;
  
  default_colormap = gdk_colormap_get_system ();
  
  retry_count = 0;
  
  while (retry_count < 2)
    {
      /* Only create a private colormap if the visual found isn't equal
       * to the default visual and we don't have a private colormap,
       * -or- if we are instructed to create a private colormap (which
       * never is the case for XmHTML).
       */
      
      if (use_private_colormap
	  || ((cc->visual != gdk_visual_get_system ()) /* default visual? */
	      && (GDK_COLORMAP_XCOLORMAP (colormap) == GDK_COLORMAP_XCOLORMAP (default_colormap))))
	{
	  g_warning ("gdk_color_context_new: non-default visual detected, "
		     "using private colormap");
	  
	  cc->colormap = gdk_colormap_new (cc->visual, FALSE);
	  
	  cc->need_to_free_colormap = (GDK_COLORMAP_XCOLORMAP (colormap)
				       != GDK_COLORMAP_XCOLORMAP (default_colormap));
	}
      
      switch (visual->type)
	{
	case GDK_VISUAL_STATIC_GRAY:
	case GDK_VISUAL_GRAYSCALE:
	  GDK_NOTE (COLOR_CONTEXT,
		    g_message ("gdk_color_context_new: visual class is %s\n",
			       (visual->type == GDK_VISUAL_STATIC_GRAY) ?
			       "GDK_VISUAL_STATIC_GRAY" :
			       "GDK_VISUAL_GRAYSCALE"));
	  
	  if (GDK_VISUAL_XVISUAL (cc->visual)->map_entries == 2)
	    init_bw (cc);
	  else
	    init_gray (cc);
	  
	  break;
	  
	case GDK_VISUAL_TRUE_COLOR: /* shifts */
	  GDK_NOTE (COLOR_CONTEXT,
		    g_message ("gdk_color_context_new: visual class is GDK_VISUAL_TRUE_COLOR\n"));
	  
	  init_true_color (cc);
	  break;
	  
	case GDK_VISUAL_DIRECT_COLOR: /* shifts and fake CLUT */
	  GDK_NOTE (COLOR_CONTEXT,
		    g_message ("gdk_color_context_new: visual class is GDK_VISUAL_DIRECT_COLOR\n"));
	  
	  init_direct_color (cc);
	  break;
	  
	case GDK_VISUAL_STATIC_COLOR:
	case GDK_VISUAL_PSEUDO_COLOR:
	  GDK_NOTE (COLOR_CONTEXT,
		    g_message ("gdk_color_context_new: visual class is %s\n",
			       (visual->type == GDK_VISUAL_STATIC_COLOR) ?
			       "GDK_VISUAL_STATIC_COLOR" :
			       "GDK_VISUAL_PSEUDO_COLOR"));
	  
	  init_color (cc);
	  break;
	  
	default:
	  g_assert_not_reached ();
	}
      
      if ((cc->mode == GDK_CC_MODE_BW) && (cc->visual->depth > 1))
	{
	  use_private_colormap = TRUE;
	  retry_count++;
	}
      else
	break;
    }
  
  /* no. of colors allocated yet */
  
  cc->num_allocated = 0;
  
  GDK_NOTE (COLOR_CONTEXT,
	    g_message ("gdk_color_context_new: screen depth is %i, no. of colors is %i\n",
		       cc->visual->depth, cc->num_colors));
  
  return (GdkColorContext *) cc;
}

GdkColorContext *
gdk_color_context_new_mono (GdkVisual   *visual,
			    GdkColormap *colormap)
{
  GdkColorContextPrivate *ccp;
  GdkColorContext *cc;
  
  g_assert (visual != NULL);
  g_assert (colormap != NULL);
  
  cc = g_new (GdkColorContext, 1);
  ccp = (GdkColorContextPrivate *) cc;
  ccp->xdisplay = gdk_display;
  cc->visual = visual;
  cc->colormap = colormap;
  cc->clut = NULL;
  cc->cmap = NULL;
  cc->mode = GDK_CC_MODE_UNDEFINED;
  cc->need_to_free_colormap = FALSE;
  
  init_bw (cc);
  
  return (GdkColorContext *) cc;
}

/* This doesn't currently free black/white, hmm... */

void
gdk_color_context_free (GdkColorContext *cc)
{
  g_assert (cc != NULL);
  
  if ((cc->visual->type == GDK_VISUAL_STATIC_COLOR)
      || (cc->visual->type == GDK_VISUAL_PSEUDO_COLOR))
    {
      gdk_colors_free (cc->colormap, cc->clut, cc->num_allocated, 0);
      g_free (cc->clut);
    }
  else if (cc->clut != NULL)
    {
      gdk_colors_free (cc->colormap, cc->clut, cc->num_colors, 0);
      g_free (cc->clut);
    }
  
  if (cc->cmap != NULL)
    g_free (cc->cmap);
  
  if (cc->need_to_free_colormap)
    gdk_colormap_unref (cc->colormap);
  
  /* free any palette that has been associated with this GdkColorContext */

  init_palette (cc);
  
  g_free (cc);
}

gulong
gdk_color_context_get_pixel (GdkColorContext *cc,
			     gushort          red,
			     gushort          green,
			     gushort          blue,
			     gint            *failed)
{
  GdkColorContextPrivate *ccp = (GdkColorContextPrivate *) cc;
  g_assert (cc != NULL);
  g_assert (failed != NULL);
  
  *failed = FALSE;
  
  switch (cc->mode)
    {
    case GDK_CC_MODE_BW:
    {
      gdouble value;
      
      value = (red / 65535.0 * 0.30
	       + green / 65535.0 * 0.59
	       + blue / 65535.0 * 0.11);
      
      if (value > 0.5)
	return cc->white_pixel;
      
      return cc->black_pixel;
    }
    
    case GDK_CC_MODE_MY_GRAY:
    {
      gulong ired, igreen, iblue;
      
      red   = red * 0.30 + green * 0.59 + blue * 0.11;
      green = 0;
      blue  = 0;
      
      if ((ired = red * (ccp->std_cmap.red_max + 1) / 0xffff) > ccp->std_cmap.red_max)
	ired = ccp->std_cmap.red_max;
      
      ired *= ccp->std_cmap.red_mult;
      
      if ((igreen = green * (ccp->std_cmap.green_max + 1) / 0xffff) > ccp->std_cmap.green_max)
	igreen = ccp->std_cmap.green_max;
      
      igreen *= ccp->std_cmap.green_mult;
      
      if ((iblue = blue * (ccp->std_cmap.blue_max + 1) / 0xffff) > ccp->std_cmap.blue_max)
	iblue = ccp->std_cmap.blue_max;
      
      iblue *= ccp->std_cmap.blue_mult;
      
      if (cc->clut != NULL)
	return cc->clut[ccp->std_cmap.base_pixel + ired + igreen + iblue];
      
      return ccp->std_cmap.base_pixel + ired + igreen + iblue;
    }
    
    case GDK_CC_MODE_TRUE:
    {
      gulong ired, igreen, iblue;
      
      if (cc->clut == NULL)
	{
	  red   >>= 16 - cc->bits.red;
	  green >>= 16 - cc->bits.green;
	  blue  >>= 16 - cc->bits.blue;
	  
	  ired   = (red << cc->shifts.red) & cc->masks.red;
	  igreen = (green << cc->shifts.green) & cc->masks.green;
	  iblue  = (blue << cc->shifts.blue) & cc->masks.blue;
	  
	  return ired | igreen | iblue;
	}
      
      ired   = cc->clut[red * cc->max_entry / 65535] & cc->masks.red;
      igreen = cc->clut[green * cc->max_entry / 65535] & cc->masks.green;
      iblue  = cc->clut[blue * cc->max_entry / 65535] & cc->masks.blue;
      
      return ired | igreen | iblue;
    }
    
    case GDK_CC_MODE_PALETTE:
      return gdk_color_context_get_pixel_from_palette (cc, &red, &green, &blue, failed);
      
    case GDK_CC_MODE_STD_CMAP:
    default:
    {
      GdkColor color;
      GdkColor *result = NULL;
      
      color.red   = red;
      color.green = green;
      color.blue  = blue;

      if (cc->color_hash)
	result = g_hash_table_lookup (cc->color_hash, &color);
      
      if (!result)
	{
	  color.red   = red;
	  color.green = green;
	  color.blue  = blue;
	  color.pixel = 0;
	  
	  if (!gdk_color_alloc (cc->colormap, &color))
	    *failed = TRUE;
	  else
	    {
	      GdkColor *cnew;
	      
	      /* XXX: the following comment comes directly from
	       * XCC.c.  I don't know if it is relevant for
	       * gdk_color_alloc() as it is for XAllocColor()
	       * - Federico
	       */
	      /*
	       * I can't figure this out entirely, but it *is* possible
	       * that XAllocColor succeeds, even if the number of
	       * allocations we've made exceeds the number of available
	       * colors in the current colormap. And therefore it
	       * might be necessary for us to resize the CLUT.
	       */
	      
	      if (cc->num_allocated == cc->max_colors)
		{
		  cc->max_colors *= 2;
		  
		  GDK_NOTE (COLOR_CONTEXT,
			    g_message ("gdk_color_context_get_pixel: "
				       "resizing CLUT to %i entries\n",
				       cc->max_colors));
		  
		  cc->clut = g_realloc (cc->clut,
					cc->max_colors * sizeof (gulong));
		}
	      
	      /* Key and value are the same color structure */
	      
	      cnew = g_new (GdkColor, 1);
	      *cnew = color;
	      
	      if (!cc->color_hash)
		cc->color_hash = g_hash_table_new (hash_color, compare_colors);
	      g_hash_table_insert (cc->color_hash, cnew, cnew);
	      
	      cc->clut[cc->num_allocated] = color.pixel;
	      cc->num_allocated++;
	      return color.pixel;
	    }
	}
      
      return result->pixel;
    }
    }
}

void
gdk_color_context_get_pixels (GdkColorContext *cc,
			      gushort         *reds,
			      gushort         *greens,
			      gushort         *blues,
			      gint             ncolors,
			      gulong          *colors,
			      gint            *nallocated)
{
  gint i, k, idx;
  gint cmapsize, ncols = 0, nopen = 0, counter = 0;
  gint bad_alloc = FALSE;
  gint failed[MAX_IMAGE_COLORS], allocated[MAX_IMAGE_COLORS];
  GdkColor defs[MAX_IMAGE_COLORS], cmap[MAX_IMAGE_COLORS];
#ifdef G_ENABLE_DEBUG  
  gint exact_col = 0, subst_col = 0, close_col = 0, black_col = 0;
#endif
  g_assert (cc != NULL);
  g_assert (reds != NULL);
  g_assert (greens != NULL);
  g_assert (blues != NULL);
  g_assert (colors != NULL);
  g_assert (nallocated != NULL);
  
  memset (defs, 0, MAX_IMAGE_COLORS * sizeof (GdkColor));
  memset (failed, 0, MAX_IMAGE_COLORS * sizeof (gint));
  memset (allocated, 0, MAX_IMAGE_COLORS * sizeof (gint));
  
  /* Will only have a value if used by the progressive image loader */
  
  ncols = *nallocated;
  
  *nallocated = 0;
  
  /* First allocate all pixels */
  
  for (i = 0; i < ncolors; i++)
    {
      /* colors[i] is only zero if the pixel at that location hasn't
       * been allocated yet.  This is a sanity check required for proper
       * color allocation by the progressive image loader
       */
      
      if (colors[i] == 0)
	{
	  defs[i].red   = reds[i];
	  defs[i].green = greens[i];
	  defs[i].blue  = blues[i];
	  
	  colors[i] = gdk_color_context_get_pixel (cc, reds[i], greens[i], blues[i],
						   &bad_alloc);
	  
	  /* successfully allocated, store it */
	  
	  if (!bad_alloc)
	    {
	      defs[i].pixel = colors[i];
	      allocated[ncols++] = colors[i];
	    }
	  else
	    failed[nopen++] = i;
	}
    }
  
  *nallocated = ncols;
  
  /* all colors available, all done */
  
  if ((ncols == ncolors) || (nopen == 0))
    {
      GDK_NOTE (COLOR_CONTEXT,
		g_message ("gdk_color_context_get_pixels: got all %i colors; "
			   "(%i colors allocated so far)\n", ncolors, cc->num_allocated));
      
      return;
    }
  
  /* The fun part.  We now try to allocate the colors we couldn't allocate
   * directly.  The first step will map a color onto its nearest color
   * that has been allocated (either by us or someone else).  If any colors
   * remain unallocated, we map these onto the colors that we have allocated
   * ourselves.
   */
  
  /* read up to MAX_IMAGE_COLORS colors of the current colormap */
  
  cmapsize = MIN (cc->num_colors, MAX_IMAGE_COLORS);
  
  /* see if the colormap has any colors to read */
  
  if (cmapsize < 0)
    {
      g_warning ("gdk_color_context_get_pixels: oops!  no colors available, "
		 "your images will look *really* ugly.");
      
      return;
    }
  
#ifdef G_ENABLE_DEBUG
  exact_col = ncols;
#endif
  
  /* initialize pixels */
  
  for (i = 0; i < cmapsize; i++)
    {
      cmap[i].pixel = i;
      cmap[i].red = cmap[i].green = cmap[i].blue = 0;
    }
  
  /* read the colormap */
  
  my_x_query_colors (cc->colormap, cmap, cmapsize);
  
  /* get a close match for any unallocated colors */
  
  counter = nopen;
  nopen = 0;
  idx = 0;
  
  do
    {
      gint d, j, mdist, close, ri, gi, bi;
      gint rd, gd, bd;
      
      i = failed[idx];
      
      mdist = 0x1000000;
      close = -1;
      
      /* Store these vals.  Small performance increase as this skips three
       * indexing operations in the loop code.
       */
      
      ri = reds[i];
      gi = greens[i];
      bi = blues[i];
      
      /* Walk all colors in the colormap and see which one is the
       * closest.  Uses plain least squares.
       */
      
      for (j = 0; (j < cmapsize) && (mdist != 0); j++)
	{
	  /* Don't replace these by shifts; the sign may get clobbered */
	  
	  rd = (ri - cmap[j].red) / 256;
	  gd = (gi - cmap[j].green) / 256;
	  bd = (bi - cmap[j].blue) / 256;
	  
	  d = rd * rd + gd * gd + bd * bd;
	  
	  if (d < mdist)
	    {
	      close = j;
	      mdist = d;
	    }
	}
      
      if (close != -1)
	{
	  rd = cmap[close].red;
	  gd = cmap[close].green;
	  bd = cmap[close].blue;
	  
	  /* allocate */
	  
	  colors[i] = gdk_color_context_get_pixel (cc, rd, gd, bd, &bad_alloc);
	  
	  /* store */
	  
	  if (!bad_alloc)
	    {
	      defs[i] = cmap[close];
	      defs[i].pixel = colors[i];
	      allocated[ncols++] = colors[i];
#ifdef G_ENABLE_DEBUG
	      close_col++;
#endif
	    } else
	      failed[nopen++] = i;
	} else
	  failed[nopen++] = i;
      /* deal with in next stage if allocation failed */
    }
  while (++idx < counter);
  
  *nallocated = ncols;
  
  /* This is the maximum no. of allocated colors.  See also the nopen == 0
   * note above.
   */
  
  if ((ncols == ncolors) || (nopen == 0))
    {
      GDK_NOTE (COLOR_CONTEXT,
		g_message ("gdk_color_context_get_pixels: got %i colors, %i exact and "
			   "%i close (%i colors allocated so far)\n",
			   ncolors, exact_col, close_col, cc->num_allocated));
      
      return;
    }
  
  /* Now map any remaining unallocated pixels into the colors we did get */
  
  idx = 0;
  
  do
    {
      gint d, mdist, close, ri, gi, bi;
      gint j, rd, gd, bd;
      
      i = failed[idx];
      
      mdist = 0x1000000;
      close = -1;
      
      /* store */
      
      ri = reds[i];
      gi = greens[i];
      bi = blues[i];
      
      /* search allocated colors */
      
      for (j = 0; (j < ncols) && (mdist != 0); j++)
	{
	  k = allocated[j];
	  
	  /* Don't replace these by shifts; the sign may get clobbered */
	  
	  rd = (ri - defs[k].red) / 256;
	  gd = (gi - defs[k].green) / 256;
	  bd = (bi - defs[k].blue) / 256;
	  
	  d = rd * rd + gd * gd + bd * bd;
	  
	  if (d < mdist)
	    {
	      close = k;
	      mdist = d;
	    }
	}
      
      if (close < 0)
	{
	  /* too bad, map to black */
	  
	  defs[i].pixel = cc->black_pixel;
	  defs[i].red = defs[i].green = defs[i].blue = 0;
#ifdef G_ENABLE_DEBUG
	  black_col++;
#endif
	}
      else
	{
	  defs[i] = defs[close];
#ifdef G_ENABLE_DEBUG
	  subst_col++;
#endif
	}
      
      colors[i] = defs[i].pixel;
    }
  while (++idx < nopen);
  
  GDK_NOTE (COLOR_CONTEXT,
	    g_message ("gdk_color_context_get_pixels: got %i colors, %i exact, %i close, "
		       "%i substituted, %i to black (%i colors allocated so far)\n",
		       ncolors, exact_col, close_col, subst_col, black_col, cc->num_allocated));
}

void
gdk_color_context_get_pixels_incremental (GdkColorContext *cc,
					  gushort         *reds,
					  gushort         *greens,
					  gushort         *blues,
					  gint             ncolors,
					  gint            *used,
					  gulong          *colors,
					  gint            *nallocated)
{
  gint i, k, idx;
  gint cmapsize, ncols = 0, nopen = 0, counter = 0;
  gint bad_alloc = FALSE;
  gint failed[MAX_IMAGE_COLORS], allocated[MAX_IMAGE_COLORS];
  GdkColor defs[MAX_IMAGE_COLORS], cmap[MAX_IMAGE_COLORS];
#ifdef G_ENABLE_DEBUG  
  gint exact_col = 0, subst_col = 0, close_col = 0, black_col = 0;
#endif  
  
  g_assert (cc != NULL);
  g_assert (reds != NULL);
  g_assert (greens != NULL);
  g_assert (blues != NULL);
  g_assert (used != NULL);
  g_assert (colors != NULL);
  g_assert (nallocated != NULL);
  
  memset (defs, 0, MAX_IMAGE_COLORS * sizeof (GdkColor));
  memset (failed, 0, MAX_IMAGE_COLORS * sizeof (gint));
  memset (allocated, 0, MAX_IMAGE_COLORS * sizeof (gint));
  
  /* Will only have a value if used by the progressive image loader */
  
  ncols = *nallocated;
  
  *nallocated = 0;
  
  /* First allocate all pixels */
  
  for (i = 0; i < ncolors; i++)
    {
      /* used[i] is only -1 if the pixel at that location hasn't
       * been allocated yet.  This is a sanity check required for proper
       * color allocation by the progressive image loader.
       * When colors[i] == 0 it indicates the slot is available for
       * allocation.
       */
      
      if (used[i] != FALSE)
	{
	  if (colors[i] == 0)
	    {
	      defs[i].red   = reds[i];
	      defs[i].green = greens[i];
	      defs[i].blue  = blues[i];
	      
	      colors[i] = gdk_color_context_get_pixel (cc, reds[i], greens[i], blues[i], &bad_alloc);
	      
	      /* successfully allocated, store it */
	      
	      if (!bad_alloc)
		{
		  defs[i].pixel = colors[i];
		  allocated[ncols++] = colors[i];
		}
	      else
		failed[nopen++] = i;
	    }
#ifdef DEBUG
	  else
	    GDK_NOTE (COLOR_CONTEXT,
		      g_message ("gdk_color_context_get_pixels_incremental: "
				 "pixel at slot %i already allocated, skipping\n", i));
#endif
	}
    }
  
  *nallocated = ncols;
  
  if ((ncols == ncolors) || (nopen == 0))
    {
      GDK_NOTE (COLOR_CONTEXT,
		g_message ("gdk_color_context_get_pixels_incremental: got all %i colors "
			   "(%i colors allocated so far)\n",
			   ncolors, cc->num_allocated));
      
      return;
    }
  
  cmapsize = MIN (cc->num_colors, MAX_IMAGE_COLORS);
  
  if (cmapsize < 0)
    {
      g_warning ("gdk_color_context_get_pixels_incremental: oops!  "
		 "No colors available images will look *really* ugly.");
      return;
    }
  
#ifdef G_ENABLE_DEBUG
  exact_col = ncols;
#endif
  
  /* initialize pixels */
  
  for (i = 0; i < cmapsize; i++)
    {
      cmap[i].pixel = i;
      cmap[i].red = cmap[i].green = cmap[i].blue = 0;
    }
  
  /* read */
  
  my_x_query_colors (cc->colormap, cmap, cmapsize);
  
  /* now match any unallocated colors */
  
  counter = nopen;
  nopen = 0;
  idx = 0;
  
  do
    {
      gint d, j, mdist, close, ri, gi, bi;
      gint rd, gd, bd;
      
      i = failed[idx];
      
      mdist = 0x1000000;
      close = -1;
      
      /* store */
      
      ri = reds[i];
      gi = greens[i];
      bi = blues[i];
      
      for (j = 0; (j < cmapsize) && (mdist != 0); j++)
	{
	  /* Don't replace these by shifts; the sign may get clobbered */
	  
	  rd = (ri - cmap[j].red) / 256;
	  gd = (gi - cmap[j].green) / 256;
	  bd = (bi - cmap[j].blue) / 256;
	  
	  d = rd * rd + gd * gd + bd * bd;
	  
	  if (d < mdist)
	    {
	      close = j;
	      mdist = d;
	    }
	}
      
      if (close != -1)
	{
	  rd = cmap[close].red;
	  gd = cmap[close].green;
	  bd = cmap[close].blue;
	  
	  /* allocate */
	  
	  colors[i] = gdk_color_context_get_pixel (cc, rd, gd, bd, &bad_alloc);
	  
	  /* store */
	  
	  if (!bad_alloc)
	    {
	      defs[i] = cmap[close];
	      defs[i].pixel = colors[i];
	      allocated[ncols++] = colors[i];
#ifdef G_ENABLE_DEBUG
	      close_col++;
#endif
	    }
	  else
	    failed[nopen++] = i;
	}
      else
	failed[nopen++] = i;
      /* deal with in next stage if allocation failed */
    }
  while (++idx < counter);
  
  *nallocated = ncols;
  
  if ((ncols == ncolors) || (nopen == 0))
    {
      GDK_NOTE (COLOR_CONTEXT,
		g_message ("gdk_color_context_get_pixels_incremental: "
			   "got %i colors, %i exact and %i close "
			   "(%i colors allocated so far)\n",
			   ncolors, exact_col, close_col, cc->num_allocated));
      
      return;
    }
  
  /* map remaining unallocated pixels into colors we did get */
  
  idx = 0;
  
  do
    {
      gint d, mdist, close, ri, gi, bi;
      gint j, rd, gd, bd;
      
      i = failed[idx];
      
      mdist = 0x1000000;
      close = -1;
      
      ri = reds[i];
      gi = greens[i];
      bi = blues[i];
      
      /* search allocated colors */
      
      for (j = 0; (j < ncols) && (mdist != 0); j++)
	{
	  k = allocated[j];
	  
	  /* downscale */
	  /* Don't replace these by shifts; the sign may get clobbered */
	  
	  rd = (ri - defs[k].red) / 256;
	  gd = (gi - defs[k].green) / 256;
	  bd = (bi - defs[k].blue) / 256;
	  
	  d = rd * rd + gd * gd + bd * bd;
	  
	  if (d < mdist)
	    {
	      close = k;
	      mdist = d;
	    }
	}
      
      if (close < 0)
	{
	  /* too bad, map to black */
	  
	  defs[i].pixel = cc->black_pixel;
	  defs[i].red = defs[i].green = defs[i].blue = 0;
#ifdef G_ENABLE_DEBUG
	  black_col++;
#endif
	}
      else
	{
	  defs[i] = defs[close];
#ifdef G_ENABLE_DEBUG
	  subst_col++;
#endif
	}
      
      colors[i] = defs[i].pixel;
    }
  while (++idx < nopen);
  
  GDK_NOTE (COLOR_CONTEXT,
	    g_message ("gdk_color_context_get_pixels_incremental: "
		       "got %i colors, %i exact, %i close, %i substituted, %i to black "
		       "(%i colors allocated so far)\n",
		       ncolors, exact_col, close_col, subst_col, black_col, cc->num_allocated));
}

gint
gdk_color_context_query_color (GdkColorContext *cc,
			       GdkColor        *color)
{
  return gdk_color_context_query_colors (cc, color, 1);
}

gint
gdk_color_context_query_colors (GdkColorContext *cc,
				GdkColor        *colors,
				gint             num_colors)
{
  gint i;
  GdkColor *tc;
  
  g_assert (cc != NULL);
  g_assert (colors != NULL);
  
  switch (cc->mode)
    {
    case GDK_CC_MODE_BW:
      for (i = 0, tc = colors; i < num_colors; i++, tc++)
	{
	  if (tc->pixel == cc->white_pixel)
	    tc->red = tc->green = tc->blue = 65535;
	  else
	    tc->red = tc->green = tc->blue = 0;
	}
      break;
      
    case GDK_CC_MODE_TRUE:
      if (cc->clut == NULL)
	for (i = 0, tc = colors; i < num_colors; i++, tc++)
	  {
	    tc->red   = ((tc->pixel & cc->masks.red) >> cc->shifts.red) << (16 - cc->bits.red);
	    tc->green = ((tc->pixel & cc->masks.green) >> cc->shifts.green) << (16 - cc->bits.green);
	    tc->blue  = ((tc->pixel & cc->masks.blue) >> cc->shifts.blue) << (16 - cc->bits.blue);
	  }
      else
	{
	  my_x_query_colors (cc->colormap, colors, num_colors);
	  return 1;
	}
      break;
      
    case GDK_CC_MODE_STD_CMAP:
    default:
      if (cc->cmap == NULL)
	{
	  my_x_query_colors (cc->colormap, colors, num_colors);
	  return 1;
	}
      else
	{
	  gint first, last, half;
	  gulong half_pixel;
	  
	  for (i = 0, tc = colors; i < num_colors; i++)
	    {
	      first = 0;
	      last = cc->num_colors - 1;
	      
	      while (first <= last)
		{
		  half = (first + last) / 2;
		  half_pixel = cc->cmap[half].pixel;
		  
		  if (tc->pixel == half_pixel)
		    {
		      tc->red   = cc->cmap[half].red;
		      tc->green = cc->cmap[half].green;
		      tc->blue  = cc->cmap[half].blue;
		      first = last + 1; /* false break */
		    }
		  else
		    {
		      if (tc->pixel > half_pixel)
			first = half + 1;
		      else
			last = half - 1;
		    }
		}
	    }
	  return 1;
	}
      break;
    }
  return 1;
}

gint
gdk_color_context_add_palette (GdkColorContext *cc,
			       GdkColor        *palette,
			       gint             num_palette)
{
  gint i, j, erg;
  gushort r, g, b;
  gulong pixel[1];
  
  g_assert (cc != NULL);
  
  /* initialize this palette (will also erase previous palette as well) */
  
  init_palette (cc);
  
  /* restore previous mode if we aren't adding a new palette */
  
  if (num_palette == 0)
    return 0;
  
  /* copy incoming palette */
  
  cc->palette = g_new0(GdkColor, num_palette);
  
  j = 0;
  
  for (i = 0; i < num_palette; i++)
    {
      erg = 0;
      pixel[0] = 0;
      
      /* try to allocate this color */
      
      r = palette[i].red;
      g = palette[i].green;
      b = palette[i].blue;
      
      gdk_color_context_get_pixels (cc, &r, &g, &b, 1, pixel, &erg);
      
      /* only store if we succeed */
      
      if (erg)
	{
	  /* store in palette */
	  
	  cc->palette[j].red   = r;
	  cc->palette[j].green = g;
	  cc->palette[j].blue  = b;
	  cc->palette[j].pixel = pixel[0];
	  
	  /* move to next slot */
	  
	  j++;
	}
    }
  
  /* resize to fit */
  
  if (j != num_palette)
    cc->palette = g_realloc (cc->palette, j * sizeof (GdkColor));
  
  /* clear the hash table, we don't use it when dithering */
  
  if (cc->color_hash)
    {
      g_hash_table_foreach (cc->color_hash,
			    free_hash_entry,
			    NULL);
      g_hash_table_destroy (cc->color_hash);
      cc->color_hash = NULL;
    }
  
  /* store real palette size */
  
  cc->num_palette = j;
  
  /* switch to palette mode */
  
  cc->mode = GDK_CC_MODE_PALETTE;
  
  /* sort palette */
  
  qsort (cc->palette, cc->num_palette, sizeof (GdkColor), pixel_sort);
  
  cc->fast_dither = NULL;
  
  return j;
}

void
gdk_color_context_init_dither (GdkColorContext *cc)
{
  gint rr, gg, bb, err, erg, erb;
  gint success = FALSE;
  
  g_assert (cc != NULL);
  
  /* now we can initialize the fast dither matrix */
  
  if (cc->fast_dither == NULL)
    cc->fast_dither = g_new (GdkColorContextDither, 1);
  
  /* Fill it.  We ignore unsuccessful allocations, they are just mapped
   * to black instead */
  
  for (rr = 0; rr < 32; rr++)
    for (gg = 0; gg < 32; gg++)
      for (bb = 0; bb < 32; bb++)
	{
	  err = (rr << 3) | (rr >> 2);
	  erg = (gg << 3) | (gg >> 2);
	  erb = (bb << 3) | (bb >> 2);
	  
	  cc->fast_dither->fast_rgb[rr][gg][bb] =
	    gdk_color_context_get_index_from_palette (cc, &err, &erg, &erb, &success);
	  cc->fast_dither->fast_err[rr][gg][bb] = err;
	  cc->fast_dither->fast_erg[rr][gg][bb] = erg;
	  cc->fast_dither->fast_erb[rr][gg][bb] = erb;
	}
}

void
gdk_color_context_free_dither (GdkColorContext *cc)
{
  g_assert (cc != NULL);
  
  if (cc->fast_dither)
    g_free (cc->fast_dither);
  
  cc->fast_dither = NULL;
}

gulong
gdk_color_context_get_pixel_from_palette (GdkColorContext *cc,
					  gushort         *red,
					  gushort         *green,
					  gushort         *blue,
					  gint            *failed)
{
  gulong pixel = 0;
  gint dif, dr, dg, db, j = -1;
  gint mindif = 0x7fffffff;
  gint err = 0, erg = 0, erb = 0;
  gint i;
  
  g_assert (cc != NULL);
  g_assert (red != NULL);
  g_assert (green != NULL);
  g_assert (blue != NULL);
  g_assert (failed != NULL);
  
  *failed = FALSE;
  
  for (i = 0; i < cc->num_palette; i++)
    {
      dr = *red - cc->palette[i].red;
      dg = *green - cc->palette[i].green;
      db = *blue - cc->palette[i].blue;
      
      dif = dr * dr + dg * dg + db * db;
      
      if (dif < mindif)
	{
	  mindif = dif;
	  j = i;
	  pixel = cc->palette[i].pixel;
	  err = dr;
	  erg = dg;
	  erb = db;
	  
	  if (mindif == 0)
	    break;
	}
    }
  
  /* we failed to map onto a color */
  
  if (j == -1)
    *failed = TRUE;
  else
    {
      *red   = ABS (err);
      *green = ABS (erg);
      *blue  = ABS (erb);
    }
  
  return pixel;
}

guchar
gdk_color_context_get_index_from_palette (GdkColorContext *cc,
					  gint            *red,
					  gint            *green,
					  gint            *blue,
					  gint            *failed)
{
  gint dif, dr, dg, db, j = -1;
  gint mindif = 0x7fffffff;
  gint err = 0, erg = 0, erb = 0;
  gint i;
  
  g_assert (cc != NULL);
  g_assert (red != NULL);
  g_assert (green != NULL);
  g_assert (blue != NULL);
  g_assert (failed != NULL);
  
  *failed = FALSE;
  
  for (i = 0; i < cc->num_palette; i++)
    {
      dr = *red - cc->palette[i].red;
      dg = *green - cc->palette[i].green;
      db = *blue - cc->palette[i].blue;
      
      dif = dr * dr + dg * dg + db * db;
      
      if (dif < mindif)
	{
	  mindif = dif;
	  j = i;
	  err = dr;
	  erg = dg;
	  erb = db;
	  
	  if (mindif == 0)
	    break;
	}
    }
  
  /* we failed to map onto a color */
  
  if (j == -1)
    {
      *failed = TRUE;
      j = 0;
    }
  else
    {
      /* return error fractions */
      
      *red   = err;
      *green = erg;
      *blue  = erb;
    }
  
  return j;
}