/* Copyright (C) 1999 Aladdin Enterprises.  All rights reserved.
  
  This program is free software; you can redistribute it and/or modify it
  under the terms of the GNU General Public License version 2
  as published by the Free Software Foundation.


  This software is provided AS-IS with no warranty, either express or
  implied. That is, this program 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
  General Public License for more details

  You should have received a copy of the GNU General Public License along
  with this program; if not, write to the Free Software Foundation, Inc.,
  59 Temple Place, Suite 330, Boston, MA, 02111-1307.
  
  For more information about licensing, please refer to
  http://www.ghostscript.com/licensing/. For information on
  commercial licensing, go to http://www.artifex.com/licensing/ or
  contact Artifex Software, Inc., 101 Lucas Valley Road #110,
  San Rafael, CA  94903, U.S.A., +1(415)492-9861.
*/

/* $Id: gdevxcmp.c,v 1.8 2002/08/22 07:12:28 henrys Exp $ */
/* X Windows color mapping */
#include "math_.h"
#include "x_.h"
#include "gx.h"			/* for gx_bitmap; includes std.h */
#include "gserrors.h"
#include "gxdevice.h"
#include "gdevx.h"

/* ---------------- Utilities ---------------- */

private void
gs_x_free(void *obj, client_name_t cname)
{
    gs_free(obj, 0 /*ignored*/, 0 /*ignored*/, cname);
}

/* ---------------- Color mapping setup / cleanup ---------------- */

#if HaveStdCMap

/* Install a standard color map in the device. */
/* Sets std_cmap.* except for free_map. */
private bool
set_cmap_values(x11_cmap_values_t *values, int maxv, int mult)
{
    int i;

    if (maxv < 1 || maxv > 63 || (maxv & (maxv + 1)) ||
	(mult & (mult - 1))
	)
	return false;
    values->cv_shift = 16 - small_exact_log2(maxv + 1);
    for (i = 0; i <= maxv; ++i)
	values->nearest[i] = X_max_color_value * i / maxv;
    for (i = 0; mult != (1 << i); ++i)
	DO_NOTHING;
    values->pixel_shift = i;
    return true;
}
private void
set_std_cmap(gx_device_X *xdev, XStandardColormap *map)
{
    xdev->cman.std_cmap.map = map;
    xdev->cman.std_cmap.fast =
	set_cmap_values(&xdev->cman.std_cmap.red, map->red_max, map->red_mult) &&
	set_cmap_values(&xdev->cman.std_cmap.green, map->green_max, map->green_mult) &&
	set_cmap_values(&xdev->cman.std_cmap.blue, map->blue_max, map->blue_mult);
}

/* Get the Standard colormap if available. */
/* Uses: dpy, scr, cmap. */
private XStandardColormap *
x_get_std_cmap(gx_device_X * xdev, Atom prop)
{
    int i;
    XStandardColormap *scmap, *sp;
    int nitems;

    if (XGetRGBColormaps(xdev->dpy, RootWindowOfScreen(xdev->scr),
			 &scmap, &nitems, prop))
	for (i = 0, sp = scmap; i < nitems; i++, sp++)
	    if (xdev->cmap == sp->colormap)
		return sp;

    return NULL;
}

/* Create a Standard colormap for a TrueColor or StaticGray display. */
/* Return true if the allocation was successful. */
/* Uses: vinfo.  Sets: std_cmap.*. */
private bool
alloc_std_cmap(gx_device_X *xdev, bool colored)
{
    XStandardColormap *cmap = XAllocStandardColormap();

    if (cmap == 0)
	return false;		/* can't allocate */
    /*
     * Some buggy X servers (including XFree86) don't set any of the
     * _mask values for StaticGray visuals.  Compensate for that here.
     */
    if ((cmap->red_max = xdev->vinfo->red_mask) == 0) {
	cmap->red_max = (1 << xdev->vinfo->depth) - 1;
	cmap->red_mult = 1;
    } else {
	for (cmap->red_mult = 1; (cmap->red_max & 1) == 0;) {
	    cmap->red_max >>= 1;
	    cmap->red_mult <<= 1;
	}
    }
    if (colored) {
	for (cmap->green_max = xdev->vinfo->green_mask, cmap->green_mult = 1;
	     (cmap->green_max & 1) == 0;
	     ) {
	    cmap->green_max >>= 1;
	    cmap->green_mult <<= 1;
	}
	for (cmap->blue_max = xdev->vinfo->blue_mask, cmap->blue_mult = 1;
	     (cmap->blue_max & 1) == 0;
	     ) {
	    cmap->blue_max >>= 1;
	    cmap->blue_mult <<= 1;
	}
    } else {
        cmap->green_max = cmap->blue_max = cmap->red_max;
        cmap->green_mult = cmap->blue_mult = cmap->red_mult;
    }
    set_std_cmap(xdev, cmap);
    xdev->cman.std_cmap.free_map = true;
    return true;
}

#endif

/* Allocate the dynamic color table, if needed and possible. */
/* Uses: vinfo, cman.num_rgb.  Sets: cman.dynamic.*. */
private void
alloc_dynamic_colors(gx_device_X * xdev, int num_colors)
{
    if (num_colors > 0) {
	xdev->cman.dynamic.colors = (x11_color_t **)
	    gs_malloc(sizeof(x11_color_t *), xdev->cman.num_rgb,
		      "x11 cman.dynamic.colors");
	if (xdev->cman.dynamic.colors) {
	    int i;

	    xdev->cman.dynamic.size = xdev->cman.num_rgb;
	    xdev->cman.dynamic.shift = 16 - xdev->vinfo->bits_per_rgb;
	    for (i = 0; i < xdev->cman.num_rgb; i++)
		xdev->cman.dynamic.colors[i] = NULL;
	    xdev->cman.dynamic.max_used = min(256, num_colors);
	    xdev->cman.dynamic.used = 0;
	}
    }
}

/* Allocate an X color, updating the reverse map. */
/* Return true if the allocation was successful. */
private bool
x_alloc_color(gx_device_X *xdev, XColor *xcolor)
{
    x11_rgb_t rgb;

    rgb.rgb[0] = xcolor->red;
    rgb.rgb[1] = xcolor->green;
    rgb.rgb[2] = xcolor->blue;
    if (!XAllocColor(xdev->dpy, xdev->cmap, xcolor))
	return false;
    if (xcolor->pixel < xdev->cman.color_to_rgb.size) {
	x11_rgb_t *pxrgb = &xdev->cman.color_to_rgb.values[xcolor->pixel];

	memcpy(pxrgb->rgb, rgb.rgb, sizeof(rgb.rgb));
	pxrgb->defined = true;
    }
    return true;
}

/* Free X colors, updating the reverse map. */
private void
x_free_colors(gx_device_X *xdev, x_pixel *pixels /*[count]*/, int count)
{
    int i;
    x_pixel pixel;

    XFreeColors(xdev->dpy, xdev->cmap, pixels, count, 0);
    for (i = 0; i < count; ++i)
	if ((pixel = pixels[i]) < xdev->cman.color_to_rgb.size)
	    xdev->cman.color_to_rgb.values[pixel].defined = false;
}

/* Free a partially filled color cube or ramp. */
/* Uses: dpy, cmap.  Uses and sets: cman.dither_ramp. */
private void
free_ramp(gx_device_X * xdev, int num_used, int size)
{
    if (num_used - 1 > 0)
	x_free_colors(xdev, xdev->cman.dither_ramp + 1, num_used - 1);
    gs_x_free(xdev->cman.dither_ramp, "x11_setup_colors");
    xdev->cman.dither_ramp = NULL;
}

/* Allocate and fill in a color cube or ramp. */
/* Return true if the operation succeeded. */
/* Uses: dpy, cmap, foreground, background, cman.color_mask. */
/* Sets: cman.dither_ramp. */
private bool
setup_cube(gx_device_X * xdev, int ramp_size, bool colors)
{
    int step, num_entries;
    int max_rgb = ramp_size - 1;
    int index;

    if (colors) {
	num_entries = ramp_size * ramp_size * ramp_size;
	step = 1;		/* all colors */
    } else {
	num_entries = ramp_size;
	step = (ramp_size + 1) * ramp_size + 1;		/* gray only */
    }

    xdev->cman.dither_ramp =
	(x_pixel *) gs_malloc(sizeof(x_pixel), num_entries,
			      "gdevx setup_cube");
    if (xdev->cman.dither_ramp == NULL)
	return false;

    xdev->cman.dither_ramp[0] = xdev->foreground;
    xdev->cman.dither_ramp[num_entries - 1] = xdev->background;
    for (index = 1; index < num_entries - 1; index++) {
	int rgb_index = index * step;
	int q = rgb_index / ramp_size,
	    r = q / ramp_size,
	    g = q % ramp_size,
	    b = rgb_index % ramp_size;
	XColor xc;

	xc.red = (X_max_color_value * r / max_rgb) & xdev->cman.color_mask.red;
	xc.green = (X_max_color_value * g / max_rgb) & xdev->cman.color_mask.green;
	xc.blue = (X_max_color_value * b / max_rgb) & xdev->cman.color_mask.blue;
	if (!x_alloc_color(xdev, &xc)) {
	    free_ramp(xdev, index, num_entries);
	    return false;
	}
	xdev->cman.dither_ramp[index] = xc.pixel;
    }

    return true;
}

/* Setup color mapping. */
int
gdev_x_setup_colors(gx_device_X * xdev)
{
    char palette =
	((xdev->vinfo->class != StaticGray) &&
	 (xdev->vinfo->class != GrayScale) ? 'C' :	/* Color */
	 (xdev->vinfo->colormap_size > 2) ? 'G' :		/* GrayScale */
	 'M');		/* MonoChrome */

    if (xdev->ghostview) {
	Atom gv_colors = XInternAtom(xdev->dpy, "GHOSTVIEW_COLORS", False);
	Atom type;
	int format;
	unsigned long nitems, bytes_after;
	char *buf;

	/* Delete property if explicit dest is given */
	if (XGetWindowProperty(xdev->dpy, xdev->win, gv_colors, 0,
			       256, (xdev->dest != 0), XA_STRING,
			       &type, &format, &nitems, &bytes_after,
			       (unsigned char **)&buf) == 0 &&
	    type == XA_STRING) {
	    nitems = sscanf(buf, "%*s %ld %ld", &(xdev->foreground),
			    &(xdev->background));
	    if (nitems != 2 || (*buf != 'M' && *buf != 'G' && *buf != 'C')) {
		eprintf("Malformed GHOSTVIEW_COLOR property.\n");
		return_error(gs_error_rangecheck);
	    }
	    palette = max(palette, *buf);
	}
    } else {
	if (xdev->palette[0] == 'c')
	    xdev->palette[0] = 'C';
	else if (xdev->palette[0] == 'g')
	    xdev->palette[0] = 'G';
	else if (xdev->palette[0] == 'm')
	    xdev->palette[0] = 'M';
	palette = max(palette, xdev->palette[0]);
    }

    /* set up color mappings here */
    xdev->cman.color_mask.red = xdev->cman.color_mask.green =
	xdev->cman.color_mask.blue = X_max_color_value -
	  (X_max_color_value >> xdev->vinfo->bits_per_rgb);
    xdev->cman.match_mask = xdev->cman.color_mask; /* default */
    xdev->cman.num_rgb = 1 << xdev->vinfo->bits_per_rgb;

#if HaveStdCMap
    xdev->cman.std_cmap.map = NULL;
    xdev->cman.std_cmap.free_map = false;
#endif
    xdev->cman.dither_ramp = NULL;
    xdev->cman.dynamic.colors = NULL;
    xdev->cman.dynamic.size = 0;
    xdev->cman.dynamic.used = 0;
    switch (xdev->vinfo->depth) {
    case 1: case 2: case 4: case 8: case 16: case 24: case 32:
	xdev->color_info.depth = xdev->vinfo->depth;
	break;
    case 15:
	xdev->color_info.depth = 16;
	break;
    default:
	eprintf1("Unsupported X visual depth: %d\n", xdev->vinfo->depth);
	return_error(gs_error_rangecheck);
    }
    {	/* Set up the reverse map from pixel values to RGB. */
	int count = 1 << min(xdev->color_info.depth, 8);

	xdev->cman.color_to_rgb.values =
	    (x11_rgb_t *)gs_malloc(sizeof(x11_rgb_t), count,
				   "gdevx color_to_rgb");
	if (xdev->cman.color_to_rgb.values) {
	    int i;

	    for (i = 0; i < count; ++i)
		xdev->cman.color_to_rgb.values[i].defined = false;
	    xdev->cman.color_to_rgb.size = count;
	} else
	    xdev->cman.color_to_rgb.size = 0;
    }
    switch ((int)palette) {
    case 'C':
	xdev->color_info.num_components = 3;
	xdev->color_info.max_gray =
	    xdev->color_info.max_color = xdev->cman.num_rgb - 1;
#if HaveStdCMap
	/* Get a standard color map if available */
	if (xdev->vinfo->visual == DefaultVisualOfScreen(xdev->scr)) {
	    xdev->cman.std_cmap.map = x_get_std_cmap(xdev, XA_RGB_DEFAULT_MAP);
	} else {
	    xdev->cman.std_cmap.map = x_get_std_cmap(xdev, XA_RGB_BEST_MAP);
	}
	if (xdev->cman.std_cmap.map ||
	    (xdev->vinfo->class == TrueColor && alloc_std_cmap(xdev, true))
	    ) {
	    xdev->color_info.dither_grays = xdev->color_info.dither_colors =
		min(xdev->cman.std_cmap.map->red_max,
		    min(xdev->cman.std_cmap.map->green_max,
			xdev->cman.std_cmap.map->blue_max)) + 1;
	    if (xdev->cman.std_cmap.map)
		set_std_cmap(xdev, xdev->cman.std_cmap.map);
	} else
#endif
	    /* Otherwise set up a rgb cube of our own */
	    /* The color cube is limited to about 1/2 of the available */
	    /* colormap, the user specified maxRGBRamp (usually 5), */
	    /* or the number of representable colors */
#define CUBE(r) (r*r*r)
#define CBRT(r) pow(r, 1.0/3.0)
	{
	    int ramp_size =
		min((int)CBRT(xdev->vinfo->colormap_size / 2.0),
		    min(xdev->maxRGBRamp, xdev->cman.num_rgb));

	    while (!xdev->cman.dither_ramp && ramp_size >= 2) {
		xdev->color_info.dither_grays =
		    xdev->color_info.dither_colors = ramp_size;
		if (!setup_cube(xdev, ramp_size, true)) {
#ifdef DEBUG
		    eprintf3("Warning: failed to allocate %dx%dx%d RGB cube.\n",
			     ramp_size, ramp_size, ramp_size);
#endif
		    ramp_size--;
		    continue;
		}
	    }

	    if (!xdev->cman.dither_ramp) {
		goto grayscale;
	    }
	}

	/* Allocate the dynamic color table. */
	alloc_dynamic_colors(xdev, CUBE(xdev->cman.num_rgb) -
			     CUBE(xdev->color_info.dither_colors));
#undef CUBE
#undef CBRT
	break;
    case 'G':
grayscale:
	xdev->color_info.num_components = 1;
	xdev->color_info.max_gray = xdev->cman.num_rgb - 1;
#if HaveStdCMap
	/* Get a standard color map if available */
	xdev->cman.std_cmap.map = x_get_std_cmap(xdev, XA_RGB_GRAY_MAP);
	if (xdev->cman.std_cmap.map ||
	    (xdev->vinfo->class == StaticGray && alloc_std_cmap(xdev, false))
	    ) {
	    xdev->color_info.dither_grays =
		xdev->cman.std_cmap.map->red_max + 1;
	    if (xdev->cman.std_cmap.map)
		set_std_cmap(xdev, xdev->cman.std_cmap.map);
	} else
#endif
	    /* Otherwise set up a gray ramp of our own */
	    /* The gray ramp is limited to about 1/2 of the available */
	    /* colormap, the user specified maxGrayRamp (usually 128), */
	    /* or the number of representable grays */
	{
	    int ramp_size = min(xdev->vinfo->colormap_size / 2,
				min(xdev->maxGrayRamp, xdev->cman.num_rgb));

	    while (!xdev->cman.dither_ramp && ramp_size >= 3) {
		xdev->color_info.dither_grays = ramp_size;
		if (!setup_cube(xdev, ramp_size, false)) {
#ifdef DEBUG
		    eprintf1("Warning: failed to allocate %d level gray ramp.\n",
			     ramp_size);
#endif
		    ramp_size /= 2;
		    continue;
		}
	    }
	    if (!xdev->cman.dither_ramp) {
		goto monochrome;
	    }
	}

	/* Allocate the dynamic color table. */
	alloc_dynamic_colors(xdev, xdev->cman.num_rgb -
			     xdev->color_info.dither_grays);
	break;
    case 'M':
monochrome:
	xdev->color_info.num_components = 1;
	xdev->color_info.max_gray = 1;
	xdev->color_info.dither_grays = 2;
	break;
    default:
	eprintf1("Unknown palette: %s\n", xdev->palette);
	if (xdev->cman.color_to_rgb.values) {
	    gs_x_free(xdev->cman.color_to_rgb.values, "gdevx color_to_rgb");
	    xdev->cman.color_to_rgb.values = 0;
	}
	return_error(gs_error_rangecheck);
    }

#if HaveStdCMap
    /*
     * When comparing colors, if not halftoning, we must only compare as
     * many bits as actually fit in a pixel, even if the hardware has more.
     */
    if (!gx_device_must_halftone(xdev)) {
	if (xdev->cman.std_cmap.map) {
	    xdev->cman.match_mask.red &=
		X_max_color_value << xdev->cman.std_cmap.red.cv_shift;
	    xdev->cman.match_mask.green &=
		X_max_color_value << xdev->cman.std_cmap.green.cv_shift;
	    xdev->cman.match_mask.blue &=
		X_max_color_value << xdev->cman.std_cmap.blue.cv_shift;
	}
    }
#endif

    return 0;
}

/* Free the dynamic colors when doing an erasepage. */
/* Uses: cman.dynamic.*.  Sets: cman.dynamic.used. */
void
gdev_x_free_dynamic_colors(gx_device_X *xdev)
{
    if (xdev->cman.dynamic.colors) {
	int i;
	x11_color_t *xcp;
	x11_color_t *next;

	for (i = 0; i < xdev->cman.dynamic.size; i++) {
	    for (xcp = xdev->cman.dynamic.colors[i]; xcp; xcp = next) {
		next = xcp->next;
		if (xcp->color.pad)
		    x_free_colors(xdev, &xcp->color.pixel, 1);
		gs_x_free(xcp, "x11_dynamic_color");
	    }
	    xdev->cman.dynamic.colors[i] = NULL;
	}
	xdev->cman.dynamic.used = 0;
    }
}

/*
 * Free storage and color map entries when closing the device.
 * Uses and sets: cman.{std_cmap.map, dither_ramp, dynamic.colors,
 * color_to_rgb}.  Uses: cman.std_cmap.free_map.
 */
void
gdev_x_free_colors(gx_device_X *xdev)
{
    if (xdev->cman.std_cmap.free_map) {
	/* XFree is declared as taking a char *, not a void *! */
	XFree((void *)xdev->cman.std_cmap.map);
	xdev->cman.std_cmap.free_map = false;
    }
    xdev->cman.std_cmap.map = 0;
    if (xdev->cman.dither_ramp)
	gs_x_free(xdev->cman.dither_ramp, "x11 dither_colors");
    if (xdev->cman.dynamic.colors) {
	gdev_x_free_dynamic_colors(xdev);
	gs_x_free(xdev->cman.dynamic.colors, "x11 cman.dynamic.colors");
	xdev->cman.dynamic.colors = NULL;
    }
    if (xdev->cman.color_to_rgb.values) {
	gs_x_free(xdev->cman.color_to_rgb.values, "x11 color_to_rgb");
	xdev->cman.color_to_rgb.values = NULL;
	xdev->cman.color_to_rgb.size = 0;
    }
}

/* ---------------- Driver color mapping calls ---------------- */

/* Define a table for computing N * X_max_color_value / D for 0 <= N <= D, */
/* 1 <= D <= 7. */
/* This requires a multiply and a divide otherwise; */
/* integer multiply and divide are slow on all platforms. */
#define CV_FRACTION(n, d) ((X_color_value)(X_max_color_value * (n) / (d)))
#define ND(n, d) CV_FRACTION(n, d)
private const X_color_value cv_tab1[] = {
    ND(0,1), ND(1,1)
};
private const X_color_value cv_tab2[] = {
    ND(0,2), ND(1,2), ND(2,2)
};
private const X_color_value cv_tab3[] = {
    ND(0,3), ND(1,3), ND(2,3), ND(3,3)
};
private const X_color_value cv_tab4[] = {
    ND(0,4), ND(1,4), ND(2,4), ND(3,4), ND(4,4)
};
private const X_color_value cv_tab5[] = {
    ND(0,5), ND(1,5), ND(2,5), ND(3,5), ND(4,5), ND(5,5)
};
private const X_color_value cv_tab6[] = {
    ND(0,6), ND(1,6), ND(2,6), ND(3,6), ND(4,6), ND(5,6), ND(6,6)
};
private const X_color_value cv_tab7[] = {
    ND(0,7), ND(1,7), ND(2,7), ND(3,7), ND(4,7), ND(5,7), ND(6,7), ND(7,7)
};
#undef ND
private const X_color_value *const cv_tables[] =
{
    0, cv_tab1, cv_tab2, cv_tab3, cv_tab4, cv_tab5, cv_tab6, cv_tab7
};

/* Some C compilers don't declare the abs function in math.h. */
/* Provide one of our own. */
private inline int
iabs(int x)
{
    return (x < 0 ? -x : x);
}

/* Map RGB values to a pixel value. */
gx_color_index
gdev_x_map_rgb_color(gx_device * dev, const gx_color_value cv[])
{
    gx_device_X *const xdev = (gx_device_X *) dev;
    gx_color_value r = cv[0];
    gx_color_value g = cv[1];
    gx_color_value b = cv[2];

    /* X and ghostscript both use shorts for color values. */
    /* Set drgb to the nearest color that the device can represent. */
    X_color_value dr = r & xdev->cman.color_mask.red;
    X_color_value dg = g & xdev->cman.color_mask.green;
    X_color_value db = b & xdev->cman.color_mask.blue;

    {
	/* Foreground and background get special treatment: */
	/* They may be mapped to other colors. */
	/* Set mrgb to the color to be used for match testing. */
	X_color_value mr = r & xdev->cman.match_mask.red;
	X_color_value mg = g & xdev->cman.match_mask.green;
	X_color_value mb = b & xdev->cman.match_mask.blue;

	if ((mr | mg | mb) == 0) {	/* i.e., all 0 */
	    if_debug4('C', "[cX]%u,%u,%u => foreground = %lu\n",
		      r, g, b, (ulong) xdev->foreground);
	    return xdev->foreground;
	}
	if (mr == xdev->cman.match_mask.red &&
	    mg == xdev->cman.match_mask.green &&
	    mb == xdev->cman.match_mask.blue
	    ) {
	    if_debug4('C', "[cX]%u,%u,%u => background = %lu\n",
		      r, g, b, (ulong) xdev->background);
	    return xdev->background;
	}
    }

#define CV_DENOM (gx_max_color_value + 1)

#if HaveStdCMap
    /* check the standard colormap first */
    if (xdev->cman.std_cmap.map) {
	const XStandardColormap *cmap = xdev->cman.std_cmap.map;

	if (gx_device_has_color(xdev)) {
	    uint cr, cg, cb;	/* rgb cube indices */
	    X_color_value cvr, cvg, cvb;	/* color value on cube */

	    if (xdev->cman.std_cmap.fast) {
		cr = r >> xdev->cman.std_cmap.red.cv_shift;
		cvr = xdev->cman.std_cmap.red.nearest[cr];
		cg = g >> xdev->cman.std_cmap.green.cv_shift;
		cvg = xdev->cman.std_cmap.green.nearest[cg];
		cb = b >> xdev->cman.std_cmap.blue.cv_shift;
		cvb = xdev->cman.std_cmap.blue.nearest[cb];
	    } else {
		cr = r * (cmap->red_max + 1) / CV_DENOM;
		cg = g * (cmap->green_max + 1) / CV_DENOM;
		cb = b * (cmap->blue_max + 1) / CV_DENOM;
		cvr = X_max_color_value * cr / cmap->red_max;
		cvg = X_max_color_value * cg / cmap->green_max;
		cvb = X_max_color_value * cb / cmap->blue_max;
	    }
	    if ((iabs((int)r - (int)cvr) & xdev->cman.match_mask.red) == 0 &&
		(iabs((int)g - (int)cvg) & xdev->cman.match_mask.green) == 0 &&
		(iabs((int)b - (int)cvb) & xdev->cman.match_mask.blue) == 0) {
		gx_color_index pixel =
		    (xdev->cman.std_cmap.fast ?
		     (cr << xdev->cman.std_cmap.red.pixel_shift) +
		     (cg << xdev->cman.std_cmap.green.pixel_shift) +
		     (cb << xdev->cman.std_cmap.blue.pixel_shift) :
		     cr * cmap->red_mult + cg * cmap->green_mult +
		     cb * cmap->blue_mult) + cmap->base_pixel;

		if_debug4('C', "[cX]%u,%u,%u (std cmap) => %lu\n",
			  r, g, b, pixel);
		return pixel;
	    }
	    if_debug3('C', "[cX]%u,%u,%u (std cmap fails)\n", r, g, b);
	} else {
	    uint cr;
	    X_color_value cvr;

	    cr = r * (cmap->red_max + 1) / CV_DENOM;
	    cvr = X_max_color_value * cr / cmap->red_max;
	    if ((iabs((int)r - (int)cvr) & xdev->cman.match_mask.red) == 0) {
		gx_color_index pixel = cr * cmap->red_mult + cmap->base_pixel;

		if_debug2('C', "[cX]%u (std cmap) => %lu\n", r, pixel);
		return pixel;
	    }
	    if_debug1('C', "[cX]%u (std cmap fails)\n", r);
	}
    } else
#endif

	/* If there is no standard colormap, check the dither cube/ramp */
    if (xdev->cman.dither_ramp) {
	if (gx_device_has_color(xdev)) {
	    uint cr, cg, cb;	/* rgb cube indices */
	    X_color_value cvr, cvg, cvb;	/* color value on cube */
	    int dither_rgb = xdev->color_info.dither_colors;
	    uint max_rgb = dither_rgb - 1;

	    cr = r * dither_rgb / CV_DENOM;
	    cg = g * dither_rgb / CV_DENOM;
	    cb = b * dither_rgb / CV_DENOM;
	    if (max_rgb < countof(cv_tables)) {
		const ushort *cv_tab = cv_tables[max_rgb];

		cvr = cv_tab[cr];
		cvg = cv_tab[cg];
		cvb = cv_tab[cb];
	    } else {
		cvr = CV_FRACTION(cr, max_rgb);
		cvg = CV_FRACTION(cg, max_rgb);
		cvb = CV_FRACTION(cb, max_rgb);
	    }
	    if ((iabs((int)r - (int)cvr) & xdev->cman.match_mask.red) == 0 &&
		(iabs((int)g - (int)cvg) & xdev->cman.match_mask.green) == 0 &&
		(iabs((int)b - (int)cvb) & xdev->cman.match_mask.blue) == 0) {
		gx_color_index pixel =
		    xdev->cman.dither_ramp[CUBE_INDEX(cr, cg, cb)];

		if_debug4('C', "[cX]%u,%u,%u (dither cube) => %lu\n",
			  r, g, b, pixel);
		return pixel;
	    }
	    if_debug3('C', "[cX]%u,%u,%u (dither cube fails)\n", r, g, b);
	} else {
	    uint cr;
	    X_color_value cvr;
	    int dither_grays = xdev->color_info.dither_grays;
	    uint max_gray = dither_grays - 1;

	    cr = r * dither_grays / CV_DENOM;
	    cvr = (X_max_color_value * cr / max_gray);
	    if ((iabs((int)r - (int)cvr) & xdev->cman.match_mask.red) == 0) {
		gx_color_index pixel = xdev->cman.dither_ramp[cr];

		if_debug2('C', "[cX]%u (dither ramp) => %lu\n", r, pixel);
		return pixel;
	    }
	    if_debug1('C', "[cX]%u (dither ramp fails)\n", r);
	}
    }

    /* Finally look through the list of dynamic colors */
    if (xdev->cman.dynamic.colors) {
	int i = (dr ^ dg ^ db) >> xdev->cman.dynamic.shift;
	x11_color_t *xcp = xdev->cman.dynamic.colors[i];
	x11_color_t *prev = NULL;
	XColor xc;

	for (; xcp; prev = xcp, xcp = xcp->next)
	    if (xcp->color.red == dr && xcp->color.green == dg &&
		xcp->color.blue == db) {
		/* Promote the found entry to the front of the list. */
		if (prev) {
		    prev->next = xcp->next;
		    xcp->next = xdev->cman.dynamic.colors[i];
		    xdev->cman.dynamic.colors[i] = xcp;
		}
		if (xcp->color.pad) {
		    if_debug4('C', "[cX]%u,%u,%u (dynamic) => %lu\n",
			      r, g, b, (ulong) xcp->color.pixel);
		    return xcp->color.pixel;
		} else {
		    if_debug3('C', "[cX]%u,%u,%u (dynamic) => missing\n",
			      r, g, b);
		    return gx_no_color_index;
		}
	    }

	/* If not in our list of dynamic colors, */
	/* ask the X server and add an entry. */
	/* First check if dynamic table is exhausted */
	if (xdev->cman.dynamic.used > xdev->cman.dynamic.max_used) {
	    if_debug3('C', "[cX]%u,%u,%u (dynamic) => full\n", r, g, b);
	    return gx_no_color_index;
	}
	xcp = (x11_color_t *)
	    gs_malloc(sizeof(x11_color_t), 1, "x11_dynamic_color");
	if (!xcp)
	    return gx_no_color_index;
	xc.red = xcp->color.red = dr;
	xc.green = xcp->color.green = dg;
	xc.blue = xcp->color.blue = db;
	xcp->next = xdev->cman.dynamic.colors[i];
	xdev->cman.dynamic.colors[i] = xcp;
	xdev->cman.dynamic.used++;
	if (x_alloc_color(xdev, &xc)) {
	    xcp->color.pixel = xc.pixel;
	    xcp->color.pad = true;
	    if_debug5('c', "[cX]0x%x,0x%x,0x%x (dynamic) => added [%d]%lu\n",
		      dr, dg, db, xdev->cman.dynamic.used - 1,
		      (ulong)xc.pixel);
	    return xc.pixel;
	} else {
	    xcp->color.pad = false;
	    if_debug3('c', "[cX]0x%x,0x%x,0x%x (dynamic) => can't alloc\n",
		      dr, dg, db);
	    return gx_no_color_index;
	}
    }
    if_debug3('C', "[cX]%u,%u,%u fails\n", r, g, b);
    return gx_no_color_index;
#undef CV_DENOM
}


/* Map a pixel value back to r-g-b. */
int
gdev_x_map_color_rgb(gx_device * dev, gx_color_index color,
		     gx_color_value prgb[3])
{
    const gx_device_X *const xdev = (const gx_device_X *) dev;
#if HaveStdCMap
    const XStandardColormap *cmap = xdev->cman.std_cmap.map;
#endif

    if (color == xdev->foreground) {
	prgb[0] = prgb[1] = prgb[2] = 0;
	return 0;
    }
    if (color == xdev->background) {
	prgb[0] = prgb[1] = prgb[2] = gx_max_color_value;
	return 0;
    }
    if (color < xdev->cman.color_to_rgb.size) {
	const x11_rgb_t *pxrgb = &xdev->cman.color_to_rgb.values[color];

	if (pxrgb->defined) {
	    prgb[0] = pxrgb->rgb[0];
	    prgb[1] = pxrgb->rgb[1];
	    prgb[2] = pxrgb->rgb[2];
	    return 0;
	}
#if HaveStdCMap
    }

    /* Check the standard colormap. */
    if (cmap) {
	if (color >= cmap->base_pixel) {
	    x_pixel value = color - cmap->base_pixel;
	    uint r = (value / cmap->red_mult) % (cmap->red_max + 1);
	    uint g = (value / cmap->green_mult) % (cmap->green_max + 1);
	    uint b = (value / cmap->blue_mult) % (cmap->blue_max + 1);

	    if (value == r * cmap->red_mult + g * cmap->green_mult +
		b * cmap->blue_mult) {
		/* When mapping color buckets back to specific colors,
		 * we can choose to map them to the darkest shades
		 * (e.g., 0, 1/3, 2/3), to the lightest shades (e.g.,
		 * 1/3-epsilon, 2/3-epsilon, 1-epsilon), to the middle
		 * shades (e.g., 1/6, 1/2, 5/6), or for maximum range
		 * (e.g., 0, 1/2, 1).  The last of these matches the
		 * assumptions of the halftoning code, so that is what
		 * we choose.
		 */
		prgb[0] = r * gx_max_color_value / cmap->red_max;
		prgb[1] = g * gx_max_color_value / cmap->green_max;
		prgb[2] = b * gx_max_color_value / cmap->blue_max;
		return 0;
	    }
	}
    }
    if (color < xdev->cman.color_to_rgb.size) {
#endif
	/* Error -- undefined pixel value. */
	return_error(gs_error_unknownerror);
    }
    /*
     * Check the dither cube/ramp.  This is hardly ever used, since if
     * there are few enough colors to require dithering, the pixel values
     * are likely to be small enough to index color_to_rgb.
     */
    if (xdev->cman.dither_ramp) {
	if (gx_device_has_color(xdev)) {
	    int size = xdev->color_info.dither_colors;
	    int size3 = size * size * size;
	    int i;

	    for (i = 0; i < size3; ++i)
		if (xdev->cman.dither_ramp[i] == color) {
		    uint max_rgb = size - 1;
		    uint q = i / size,
			r = q / size,
			g = q % size,
			b = i % size;

		    /*
		     * See above regarding the choice of color mapping
		     * algorithm.
		     */
		    prgb[0] = r * gx_max_color_value / max_rgb;
		    prgb[1] = g * gx_max_color_value / max_rgb;
		    prgb[2] = b * gx_max_color_value / max_rgb;
		    return 0;
		}
	} else {
	    int size = xdev->color_info.dither_grays;
	    int i;

	    for (i = 0; i < size; ++i)
		if (xdev->cman.dither_ramp[i] == color) {
		    prgb[0] = prgb[1] = prgb[2] =
			i * gx_max_color_value / (size - 1);
		    return 0;
		}
	}
    }

    /* Finally, search the list of dynamic colors. */
    if (xdev->cman.dynamic.colors) {
	int i;
	const x11_color_t *xcp;

	for (i = xdev->cman.dynamic.size; --i >= 0;)
	    for (xcp = xdev->cman.dynamic.colors[i]; xcp; xcp = xcp->next)
		if (xcp->color.pixel == color && xcp->color.pad) {
		    prgb[0] = xcp->color.red;
		    prgb[1] = xcp->color.green;
		    prgb[2] = xcp->color.blue;
		    return 0;
		}
    }

    /* Not found -- not possible! */
    return_error(gs_error_unknownerror);
}
