gimp/app/paint_funcs.c

/* The GIMP -- an image manipulation program
 * Copyright (C) 1995 Spencer Kimball and Peter Mattis
 *
 * This program is free software; you can redistribute it and/or modify
 * it under the terms of the GNU General Public License as published by
 * the Free Software Foundation; either version 2 of the License, or
 * (at your option) any later version.
 *
 * 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, USA.
 */

#include "config.h"

#include <stdlib.h>
#include <string.h>
#include <stdio.h>

#include <glib.h>

#include "libgimpcolor/gimpcolor.h"
#include "libgimpmath/gimpmath.h"

#include "apptypes.h"

#include "gimprc.h"
#include "paint_funcs.h"
#include "pixel_processor.h"
#include "pixel_region.h"
#include "tile_manager.h"
#include "tile.h"


#define STD_BUF_SIZE       1021
#define MAXDIFF            195076
#define HASH_TABLE_SIZE    1021
#define RANDOM_TABLE_SIZE  4096
#define RANDOM_SEED        314159265
#define EPSILON            0.0001

#define INT_MULT(a,b,t)  ((t) = (a) * (b) + 0x80, ((((t) >> 8) + (t)) >> 8))

/* This version of INT_MULT3 is very fast, but suffers from some
   slight roundoff errors.  It returns the correct result 99.987
   percent of the time */
#define INT_MULT3(a,b,c,t)  ((t) = (a) * (b) * (c)+ 0x7F5B, \
                            ((((t) >> 7) + (t)) >> 16))
/*
  This version of INT_MULT3 always gives the correct result, but runs at
  approximatly one third the speed. */
/*  #define INT_MULT3(a,b,c,t) (((a) * (b) * (c)+ 32512) / 65025.0)
 */

#define INT_BLEND(a,b,alpha,tmp)  (INT_MULT((a)-(b), alpha, tmp) + (b))

typedef enum
{
  MinifyX_MinifyY,
  MinifyX_MagnifyY,
  MagnifyX_MinifyY,
  MagnifyX_MagnifyY
} ScaleType;


/*  Layer modes information  */
typedef struct _LayerMode LayerMode;
struct _LayerMode
{
  gboolean   affect_alpha;     /*  does the layer mode affect the alpha channel  */
  gboolean   increase_opacity; /*  layer mode can increase opacity */
  gboolean   decrease_opacity; /*  layer mode can decrease opacity */
};

static const LayerMode layer_modes[] =	
                               /* This must obviously be in the same
			        * order as the corresponding values
		         	* in the LayerModeEffects enumeration.
				*/
{
  { TRUE,  TRUE,  FALSE, },  /*  NORMAL_MODE        */
  { TRUE,  TRUE,  FALSE, },  /*  DISSOLVE_MODE      */
  { TRUE,  TRUE,  FALSE, },  /*  BEHIND_MODE        */
  { FALSE, FALSE, FALSE, },  /*  MULTIPLY_MODE      */
  { FALSE, FALSE, FALSE, },  /*  SCREEN_MODE        */
  { FALSE, FALSE, FALSE, },  /*  OVERLAY_MODE       */
  { FALSE, FALSE, FALSE, },  /*  DIFFERENCE_MODE    */
  { FALSE, FALSE, FALSE, },  /*  ADDITION_MODE      */
  { FALSE, FALSE, FALSE, },  /*  SUBTRACT_MODE      */
  { FALSE, FALSE, FALSE, },  /*  DARKEN_ONLY_MODE   */
  { FALSE, FALSE, FALSE, },  /*  LIGHTEN_ONLY_MODE  */
  { FALSE, FALSE, FALSE, },  /*  HUE_MODE           */
  { FALSE, FALSE, FALSE, },  /*  SATURATION_MODE    */
  { FALSE, FALSE, FALSE, },  /*  COLOR_MODE         */
  { FALSE, FALSE, FALSE, },  /*  VALUE_MODE         */
  { FALSE, FALSE, FALSE, },  /*  DIVIDE_MODE        */
  { FALSE, FALSE, FALSE, },  /*  DODGE_MODE         */
  { FALSE, FALSE, FALSE, },  /*  BURN_MODE          */
  { FALSE, FALSE, FALSE, },  /*  HARDLIGHT_MODE     */
  { TRUE,  FALSE, TRUE,  },  /*  ERASE_MODE         */
  { TRUE,  TRUE,  TRUE,  },  /*  REPLACE_MODE       */
  { TRUE,  FALSE, TRUE,  }   /*  ANTI_ERASE_MODE    */
};

/*  ColorHash structure  */
typedef struct _ColorHash ColorHash;

struct _ColorHash
{
  gint       pixel;           /*  R << 16 | G << 8 | B  */
  gint       index;           /*  colormap index        */
  GimpImage *gimage;     
};

static ColorHash  color_hash_table[HASH_TABLE_SIZE];
static gint       random_table[RANDOM_TABLE_SIZE];
static gint       color_hash_misses;
static gint       color_hash_hits;
static guchar    *tmp_buffer;  /* temporary buffer available upon request */
static gint       tmp_buffer_size;
static guchar     no_mask = OPAQUE_OPACITY;
static gint       add_lut[256][256];


/*  Local function prototypes  */

static gint *   make_curve               (gdouble  sigma,
					  gint    *length);
static void     run_length_encode        (guchar   *src,
					  gint     *dest,
					  gint      w,
					  gint      bytes);
static gdouble  cubic                    (gdouble   dx,
					  gint      jm1,
					  gint      j,
					  gint      jp1,
					  gint      jp2);
static void     apply_layer_mode_replace (guchar   *src1,
					  guchar   *src2,
					  guchar   *dest,
					  guchar   *mask,
					  gint      x,
					  gint      y,
					  gint      opacity,
					  gint      length,
					  gint      bytes1,
					  gint      bytes2,
					  gboolean *affect);
static void     rotate_pointers          (gpointer *p, 
					  guint32   n);
/* MMX stuff */
extern gboolean use_mmx;

#ifdef HAVE_ASM_MMX
extern int use_mmx;

#define MMX_PIXEL_OP(x) \
void \
x( \
  const unsigned char *src1, \
  const unsigned char *src2, \
  unsigned count, \
  unsigned char *dst) __attribute((regparm(3)));

#define MMX_PIXEL_OP_3A_1A(op) \
  MMX_PIXEL_OP(op##_pixels_3a_3a) \
  MMX_PIXEL_OP(op##_pixels_1a_1a)

#define USE_MMX_PIXEL_OP_3A_1A(op) \
  if (use_mmx && has_alpha1 && has_alpha2) \
    { \
      if (bytes1==2 && bytes2==2) \
	return op##_pixels_1a_1a(src1, src2, length, dest); \
      if (bytes1==4 && bytes2==4) \
	return op##_pixels_3a_3a(src1, src2, length, dest); \
    } \
  /*fprintf(stderr, "non-MMX: %s(%d, %d, %d, %d)\n", #op, \
    bytes1, bytes2, has_alpha1, has_alpha2);*/
#else

#define MMX_PIXEL_OP_3A_1A(op)
#define USE_MMX_PIXEL_OP_3A_1A(op)
#endif


void
update_tile_rowhints (Tile *tile,
		      gint  ymin,
		      gint  ymax)
{
  gint         bpp, ewidth;
  gint         x, y;
  guchar      *ptr;
  guchar       alpha;
  TileRowHint  thishint;

#ifdef HINTS_SANITY
  g_assert (tile != NULL);
#endif

  tile_sanitize_rowhints (tile);

  bpp = tile_bpp (tile);
  ewidth = tile_ewidth (tile);

  if (bpp == 1 || bpp == 3)
    {
      for (y = ymin; y <= ymax; y++)
	tile_set_rowhint (tile, y, TILEROWHINT_OPAQUE);

      return;
    }

  if (bpp == 4)
    {
#ifdef HINTS_SANITY
      g_assert (tile != NULL);
#endif

      ptr = tile_data_pointer (tile, 0, ymin);

#ifdef HINTS_SANITY
      g_assert (ptr != NULL);
#endif

      for (y = ymin; y <= ymax; y++)
	{
	  thishint = tile_get_rowhint (tile, y);

#ifdef HINTS_SANITY
	  if (thishint == TILEROWHINT_BROKEN)
	    g_error ("BROKEN y=%d",y);
	  if (thishint == TILEROWHINT_OUTOFRANGE)
	    g_error ("OOR y=%d",y);
	  if (thishint == TILEROWHINT_UNDEFINED)
	    g_error ("UNDEFINED y=%d - bpp=%d ew=%d eh=%d",
		     y, bpp, ewidth, eheight);
#endif

#ifdef HINTS_SANITY
	  if (thishint == TILEROWHINT_TRANSPARENT ||
	      thishint == TILEROWHINT_MIXED ||
	      thishint == TILEROWHINT_OPAQUE)
	    {
	      goto next_row4;
	    }

	  if (thishint != TILEROWHINT_UNKNOWN)
	    {
	      g_error ("MEGABOGUS y=%d - bpp=%d ew=%d eh=%d",
		       y, bpp, ewidth, eheight);
	    }
#endif

	  if (thishint == TILEROWHINT_UNKNOWN)
	    {
	      alpha = ptr[3];

	      /* row is all-opaque or all-transparent? */
	      if (alpha == 0 || alpha == 255)
		{
		  if (ewidth > 1)
		    {
		      for (x = 1; x < ewidth; x++)
			{
			  if (ptr[x * 4 + 3] != alpha)
			    {
			      tile_set_rowhint (tile, y, TILEROWHINT_MIXED);
			      goto next_row4;
			    }
			}
		    }
		  tile_set_rowhint (tile, y,
				    (alpha == 0) ?
				    TILEROWHINT_TRANSPARENT :
				    TILEROWHINT_OPAQUE);
		}
	      else
		{
		  tile_set_rowhint (tile, y, TILEROWHINT_MIXED);
		}
	    }

	next_row4:
	  ptr += 4 * ewidth;
	}
      
      return;
    }

  if (bpp == 2)
    {
#ifdef HINTS_SANITY
      g_assert (tile != NULL);
#endif

      ptr = tile_data_pointer (tile, 0, ymin);

#ifdef HINTS_SANITY
      g_assert (ptr != NULL);
#endif

      for (y = ymin; y <= ymax; y++)
	{
	  thishint = tile_get_rowhint (tile, y);

#ifdef HINTS_SANITY
	  if (thishint == TILEROWHINT_BROKEN)
	    g_error ("BROKEN y=%d",y);
	  if (thishint == TILEROWHINT_OUTOFRANGE)
	    g_error ("OOR y=%d",y);
	  if (thishint == TILEROWHINT_UNDEFINED)
	    g_error ("UNDEFINED y=%d - bpp=%d ew=%d eh=%d",
		     y, bpp, ewidth, eheight);
#endif

#ifdef HINTS_SANITY
	  if (thishint == TILEROWHINT_TRANSPARENT ||
	      thishint == TILEROWHINT_MIXED ||
	      thishint == TILEROWHINT_OPAQUE)
	    {
	      goto next_row2;
	    }

	  if (thishint != TILEROWHINT_UNKNOWN)
	    {
	      g_error ("MEGABOGUS y=%d - bpp=%d ew=%d eh=%d",
		       y, bpp, ewidth, eheight);
	    }
#endif

	  if (thishint == TILEROWHINT_UNKNOWN)
	    {
	      alpha = ptr[1];

	      /* row is all-opaque or all-transparent? */
	      if (alpha == 0 || alpha == 255)
		{
		  if (ewidth > 1)
		    {
		      for (x = 1; x < ewidth; x++)
			{
			  if (ptr[x*2 + 1] != alpha)
			    {
			      tile_set_rowhint (tile, y, TILEROWHINT_MIXED);
			      goto next_row2;
			    }
			}
		    }
		  tile_set_rowhint (tile, y,
				    (alpha == 0) ?
				    TILEROWHINT_TRANSPARENT :
				    TILEROWHINT_OPAQUE);
		}
	      else
		{
		  tile_set_rowhint (tile, y, TILEROWHINT_MIXED);
		}
	    }

	next_row2:
	  ptr += 2 * ewidth;
	}
      
      return;
    }

  g_warning ("update_tile_rowhints: Don't know about tiles with bpp==%d", bpp);
}


static guchar *
paint_funcs_get_buffer (gint size)
{
  if (size > tmp_buffer_size)
    {
      tmp_buffer_size = size;
      tmp_buffer = (guchar *) g_realloc (tmp_buffer, size);
    }

  return tmp_buffer;
}


/*
 * The equations: g(r) = exp (- r^2 / (2 * sigma^2))
 *                   r = sqrt (x^2 + y ^2)
 */

static gint *
make_curve (gdouble  sigma,
	    gint    *length)
{
  gint    *curve;
  gdouble  sigma2;
  gdouble  l;
  gint     temp;
  gint     i, n;

  sigma2 = 2 * sigma * sigma;
  l = sqrt (-sigma2 * log (1.0 / 255.0));

  n = ceil (l) * 2;
  if ((n % 2) == 0)
    n += 1;

  curve = g_new (gint, n);

  *length = n / 2;
  curve += *length;
  curve[0] = 255;

  for (i = 1; i <= *length; i++)
    {
      temp = (gint) (exp (- (i * i) / sigma2) * 255);
      curve[-i] = temp;
      curve[i] = temp;
    }

  return curve;
}


static void
run_length_encode (guchar *src,
		   gint   *dest,
		   gint    w,
		   gint    bytes)
{
  gint   start;
  gint   i;
  gint   j;
  guchar last;

  last = *src;
  src += bytes;
  start = 0;

  for (i = 1; i < w; i++)
    {
      if (*src != last)
	{
	  for (j = start; j < i; j++)
	    {
	      *dest++ = (i - j);
	      *dest++ = last;
	    }
	  start = i;
	  last = *src;
	}
      src += bytes;
    }

  for (j = start; j < i; j++)
    {
      *dest++ = (i - j);
      *dest++ = last;
    }
}

/* Note: cubic function no longer clips result */
static inline gdouble
cubic (gdouble dx,
       gint    jm1,
       gint    j,
       gint    jp1,
       gint    jp2)
{
  /* Catmull-Rom - not bad */
  return (gdouble) ((( ( - jm1 + 3 * j - 3 * jp1 + jp2 ) * dx +
		       ( 2 * jm1 - 5 * j + 4 * jp1 - jp2 ) ) * dx +
		     ( - jm1 + jp1 ) ) * dx + (j + j) ) / 2.0;
}

/*********************/
/*  FUNCTIONS        */
/*********************/

void
paint_funcs_setup (void)
{
  gint i;
  gint j, k;
  gint tmp_sum;

  /*  allocate the temporary buffer  */
  tmp_buffer      = g_new (guchar, STD_BUF_SIZE);
  tmp_buffer_size = STD_BUF_SIZE;

  /*  initialize the color hash table--invalidate all entries  */
  for (i = 0; i < HASH_TABLE_SIZE; i++)
    color_hash_table[i].gimage = NULL;
  color_hash_misses = 0;
  color_hash_hits = 0;

  /*  generate a table of random seeds  */
  srand (RANDOM_SEED);

  /* FIXME: Why creating an array of random values and shuffle it randomly
   * afterwards??? 
   */

  for (i = 0; i < RANDOM_TABLE_SIZE; i++)
    random_table[i] = rand ();

  for (i = 0; i < RANDOM_TABLE_SIZE; i++)
    {
      gint tmp;
      gint swap = i + rand () % (RANDOM_TABLE_SIZE - i);

      tmp = random_table[i];
      random_table[i] = random_table[swap];
      random_table[swap] = tmp;
    }

  for (j = 0; j < 256; j++)
    {    /* rows */
      for (k = 0; k < 256; k++)
	{   /* column */
	  tmp_sum = j + k;

	  if (tmp_sum > 255)
	    tmp_sum = 255;

	  add_lut[j][k] = tmp_sum; 
	}
    }
}

void
paint_funcs_free (void)
{
  /*  free the temporary buffer  */
  g_free (tmp_buffer);

  /*  print out the hash table statistics
      printf ("RGB->indexed hash table lookups: %d\n", color_hash_hits + color_hash_misses);
      printf ("RGB->indexed hash table hits: %d\n", color_hash_hits);
      printf ("RGB->indexed hash table misses: %d\n", color_hash_misses);
      printf ("RGB->indexed hash table hit rate: %f\n",
      100.0 * color_hash_hits / (color_hash_hits + color_hash_misses));
      */
}

void
paint_funcs_invalidate_color_hash_table (GimpImage* gimage,
					 gint       index)
{
  gint i;

  g_return_if_fail (gimage != NULL);

  if (index == -1) /* invalidate all entries */
    {
      for (i = 0; i < HASH_TABLE_SIZE; i++)
	if (color_hash_table[i].gimage == gimage)
	  color_hash_table[i].gimage = NULL;
    }
  else
    {
      for (i = 0; i < HASH_TABLE_SIZE; i++)
	if (color_hash_table[i].gimage == gimage && 
	    color_hash_table[i].index  == index)
	  color_hash_table[i].gimage = NULL;      
    }
}


void
color_pixels (guchar       *dest,
	      const guchar *color,
	      gint          w,
	      gint          bytes)
{
  /* dest % bytes and color % bytes must be 0 or we will crash 
     when bytes = 2 or 4.
     Is this safe to assume?  Lets find out.
     This is 4-7X as fast as the simple version.
     */

#if defined(sparc) || defined(__sparc__)
  register guchar   c0, c1, c2, c3;
#else
  register guchar   c0, c1, c2;
  register guint32 *longd, longc;
  register guint16 *shortd, shortc;
#endif

  switch (bytes)
    {
    case 1:
      memset (dest, *color, w);
      break;

    case 2:
#if defined(sparc) || defined(__sparc__)
      c0 = color[0];
      c1 = color[1];
      while (w--)
	{
	  dest[0] = c0;
	  dest[1] = c1;
	  dest += 2;
	}
#else
      shortc = ((guint16 *) color)[0];
      shortd = (guint16 *) dest;
      while (w--)
	{
	  *shortd = shortc;
	  shortd++;
	}
#endif /* sparc || __sparc__ */
      break;
    case 3:
      c0 = color[0];
      c1 = color[1];
      c2 = color[2];
      while (w--)
	{
	  dest[0] = c0;
	  dest[1] = c1;
	  dest[2] = c2;
	  dest += 3;
	}
      break;
    case 4:
#if defined(sparc) || defined(__sparc__)
      c0 = color[0];
      c1 = color[1];
      c2 = color[2];
      c3 = color[3];
      while (w--)
	{
	  dest[0] = c0;
	  dest[1] = c1;
	  dest[2] = c2;
	  dest[3] = c3;
	  dest += 4;
	}
#else
      longc = ((guint32 *) color)[0];
      longd = (guint32 *) dest;
      while (w--)
	{
	  *longd = longc;
	  longd++;
	}
#endif /* sparc || __sparc__ */
      break;
    default:
      while (w--)
	{
	  memcpy (dest, color, bytes);
	  dest += bytes;
	}
    }
}


void
blend_pixels (const guchar *src1,
	      const guchar *src2,
	      guchar       *dest,
	      gint          blend,
	      gint          w,
	      gint          bytes,
	      gint          has_alpha)
{
  gint   b;
  guchar blend2 = (255 - blend);

  while (w --)
    {
      for (b = 0; b < bytes; b++)
	dest[b] = (src1[b] * blend2 + src2[b] * blend) / 255;

      src1 += bytes;
      src2 += bytes;
      dest += bytes;
    }
}


void
shade_pixels (const guchar *src,
	      guchar       *dest,
	      const guchar *col,
	      gint          blend,
	      gint          w,
	      gint          bytes,
	      gint          has_alpha)
{
  gint   alpha, b;
  guchar blend2 = (255 - blend);

  alpha = (has_alpha) ? bytes - 1 : bytes;
  while (w --)
    {
      for (b = 0; b < alpha; b++)
	dest[b] = (src[b] * blend2 + col[b] * blend) / 255;

      if (has_alpha)
	dest[alpha] = src[alpha];  /* alpha channel */

      src += bytes;
      dest += bytes;
    }
}


void
extract_alpha_pixels (const guchar *src,
		      const guchar *mask,
		      guchar       *dest,
		      gint          w,
		      gint          bytes)
{
  const guchar *m;
  gint          tmp;

  const gint alpha = bytes - 1;
  
  if (mask)
    {
      m = mask;
      while (w --)
        {
          *dest++ = INT_MULT(src[alpha], *m, tmp);
          m++;
          src += bytes;
        }
    }
  else
    { 
      m = &no_mask;
      while (w --)
        { 
          *dest++ = INT_MULT(src[alpha], *m, tmp);
          src += bytes;
        }
    }
}

MMX_PIXEL_OP_3A_1A(darken)
void
darken_pixels (const guchar *src1,
	       const guchar *src2,
	       guchar       *dest,
	       gint          length,
	       gint          bytes1,
	       gint          bytes2,
	       gint          has_alpha1,
	       gint          has_alpha2)
{
  gint   b, alpha;
  guchar s1, s2;

  USE_MMX_PIXEL_OP_3A_1A(darken)

  alpha = (has_alpha1 || has_alpha2) ? MAX (bytes1, bytes2) - 1 : bytes1;

  while (length--)
    {
      for (b = 0; b < alpha; b++)
	{
	  s1 = src1[b];
	  s2 = src2[b];
	  dest[b] = (s1 < s2) ? s1 : s2;
	}

      if (has_alpha1 && has_alpha2)
	dest[alpha] = MIN (src1[alpha], src2[alpha]);
      else if (has_alpha2)
	dest[alpha] = src2[alpha];

      src1 += bytes1;
      src2 += bytes2;
      dest += bytes2;
    }
}

MMX_PIXEL_OP_3A_1A(lighten)
void
lighten_pixels (const guchar *src1,
		const guchar *src2,
		guchar       *dest,
		gint          length,
		gint          bytes1,
		gint          bytes2,
		gint          has_alpha1,
		gint          has_alpha2)
{
  gint   b, alpha;
  guchar s1, s2;

  USE_MMX_PIXEL_OP_3A_1A(lighten)

  alpha = (has_alpha1 || has_alpha2) ? MAX (bytes1, bytes2) - 1 : bytes1;

  while (length--)
    {
      for (b = 0; b < alpha; b++)
	{
	  s1 = src1[b];
	  s2 = src2[b];
	  dest[b] = (s1 < s2) ? s2 : s1;
	}

      if (has_alpha1 && has_alpha2)
	dest[alpha] = MIN (src1[alpha], src2[alpha]);
      else if (has_alpha2)
	dest[alpha] = src2[alpha];

      src1 += bytes1;
      src2 += bytes2;
      dest += bytes2;
    }
}


void
hsv_only_pixels (const guchar *src1,
		 const guchar *src2,
		 guchar       *dest,
		 gint          mode,
		 gint          length,
		 gint          bytes1,
		 gint          bytes2,
		 gint          has_alpha1,
		 gint          has_alpha2)
{
  gint r1, g1, b1;
  gint r2, g2, b2;

  /*  assumes inputs are only 4 byte RGBA pixels  */
  while (length--)
    {
      r1 = src1[0]; g1 = src1[1]; b1 = src1[2];
      r2 = src2[0]; g2 = src2[1]; b2 = src2[2];
      gimp_rgb_to_hsv_int (&r1, &g1, &b1);
      gimp_rgb_to_hsv_int (&r2, &g2, &b2);

      switch (mode)
	{
	case HUE_MODE:
	  r1 = r2;
	  break;
	case SATURATION_MODE:
	  g1 = g2;
	  break;
	case VALUE_MODE:
	  b1 = b2;
	  break;
	}

      /*  set the destination  */
      gimp_hsv_to_rgb_int (&r1, &g1, &b1);

      dest[0] = r1; dest[1] = g1; dest[2] = b1;

      if (has_alpha1 && has_alpha2)
	dest[3] = MIN (src1[3], src2[3]);
      else if (has_alpha2)
	dest[3] = src2[3];

      src1 += bytes1;
      src2 += bytes2;
      dest += bytes2;
    }
}


void
color_only_pixels (const guchar *src1,
		   const guchar *src2,
		   guchar       *dest,
		   gint          mode,
		   gint          length,
		   gint          bytes1,
		   gint          bytes2,
		   gint          has_alpha1,
		   gint          has_alpha2)
{
  gint r1, g1, b1;
  gint r2, g2, b2;

  /*  assumes inputs are only 4 byte RGBA pixels  */
  while (length--)
    {
      r1 = src1[0]; g1 = src1[1]; b1 = src1[2];
      r2 = src2[0]; g2 = src2[1]; b2 = src2[2];
      gimp_rgb_to_hls_int (&r1, &g1, &b1);
      gimp_rgb_to_hls_int (&r2, &g2, &b2);

      /*  transfer hue and saturation to the source pixel  */
      r1 = r2;
      b1 = b2;

      /*  set the destination  */
      gimp_hls_to_rgb_int (&r1, &g1, &b1);

      dest[0] = r1; dest[1] = g1; dest[2] = b1;

      if (has_alpha1 && has_alpha2)
	dest[3] = MIN (src1[3], src2[3]);
      else if (has_alpha2)
	dest[3] = src2[3];

      src1 += bytes1;
      src2 += bytes2;
      dest += bytes2;
    }
}

MMX_PIXEL_OP_3A_1A(multiply)
void
multiply_pixels (const guchar *src1,
		 const guchar *src2,
		 guchar       *dest,
		 gint          length,
		 gint          bytes1,
		 gint          bytes2,
		 gint          has_alpha1,
		 gint          has_alpha2)
{
  gint alpha, b;
  gint tmp;

  USE_MMX_PIXEL_OP_3A_1A(multiply)

  alpha = (has_alpha1 || has_alpha2) ? MAX (bytes1, bytes2) - 1 : bytes1;

  if (has_alpha1 && has_alpha2)
    {
      while (length --)
	{
	  for (b = 0; b < alpha; b++)
	    dest[b] = INT_MULT(src1[b], src2[b], tmp);

	  dest[alpha] = MIN (src1[alpha], src2[alpha]);

	  src1 += bytes1;
	  src2 += bytes2;
	  dest += bytes2;
	}
    }
  else if (has_alpha2)
    {
      while (length --)
	{
	  for (b = 0; b < alpha; b++)
	    dest[b] = INT_MULT(src1[b], src2[b], tmp);

	  dest[alpha] = src2[alpha];

	  src1 += bytes1;
	  src2 += bytes2;
	  dest += bytes2;
	}
    }
  else
    {
      while (length --)
	{
	  for (b = 0; b < alpha; b++)
	    dest[b] = INT_MULT(src1[b], src2[b], tmp);

	  src1 += bytes1;
	  src2 += bytes2;
	  dest += bytes2;
	}
    }
}


void
divide_pixels (const guchar *src1,
	       const guchar *src2,
	       guchar       *dest,
	       gint          length,
	       gint          bytes1,
	       gint          bytes2,
	       gint          has_alpha1,
	       gint          has_alpha2)
{
  gint alpha, b, result;

  alpha = (has_alpha1 || has_alpha2) ? MAX (bytes1, bytes2) - 1 : bytes1;

  while (length --)
    {
      for (b = 0; b < alpha; b++)
	{
	  result = ((src1[b] * 256) / (1+src2[b]));
	  dest[b] = MIN (result, 255);
	}

      if (has_alpha1 && has_alpha2)
	dest[alpha] = MIN (src1[alpha], src2[alpha]);
      else if (has_alpha2)
	dest[alpha] = src2[alpha];

      src1 += bytes1;
      src2 += bytes2;
      dest += bytes2;
    }
}


MMX_PIXEL_OP_3A_1A(screen)

void
screen_pixels (const guchar *src1,
	       const guchar *src2,
	       guchar       *dest,
	       gint          length,
	       gint          bytes1,
	       gint          bytes2,
	       gint          has_alpha1,
	       gint          has_alpha2)
{
  gint alpha, b;
  gint tmp;

  USE_MMX_PIXEL_OP_3A_1A(screen)

  alpha = (has_alpha1 || has_alpha2) ? MAX (bytes1, bytes2) - 1 : bytes1;

  while (length --)
    {
      for (b = 0; b < alpha; b++)
	dest[b] = 255 - INT_MULT((255 - src1[b]), (255 - src2[b]), tmp);

      if (has_alpha1 && has_alpha2)
	dest[alpha] = MIN (src1[alpha], src2[alpha]);
      else if (has_alpha2)
	dest[alpha] = src2[alpha];

      src1 += bytes1;
      src2 += bytes2;
      dest += bytes2;
    }
}


MMX_PIXEL_OP_3A_1A(overlay)

void
overlay_pixels (const guchar *src1,
		const guchar *src2,
		guchar       *dest,
		gint          length,
		gint          bytes1,
		gint          bytes2,
		gint          has_alpha1,
		gint          has_alpha2)
{
  gint alpha, b;
  gint tmp;

  alpha = (has_alpha1 || has_alpha2) ? MAX (bytes1, bytes2) - 1 : bytes1;

  while (length --)
    {
      for (b = 0; b < alpha; b++)
	{
	  dest[b] = INT_MULT(src1[b], src1[b] + INT_MULT(2 * src2[b],
							 255 - src1[b],
							 tmp), tmp);
	}

      if (has_alpha1 && has_alpha2)
	dest[alpha] = MIN (src1[alpha], src2[alpha]);
      else if (has_alpha2)
	dest[alpha] = src2[alpha];

      src1 += bytes1;
      src2 += bytes2;
      dest += bytes2;
    }
}



void
dodge_pixels (const guchar *src1,
		const guchar *src2,
		guchar *dest,
		gint            length,
		gint            b1,
		gint            b2,
		gint            ha1,
		gint            ha2)
{
  gint alpha, b;
  int tmp1;

  alpha = (ha1 || ha2) ? MAX (b1, b2) - 1 : b1;

  while (length --)
    {
      for (b = 0; b < alpha; b++)
	{
	  tmp1 = src1[b] << 8;
	  tmp1 /= 256 - src2[b];
	  dest[b] = (guchar) CLAMP (tmp1, 0, 255);
	}

      if (ha1 && ha2)
	dest[alpha] = MIN (src1[alpha], src2[alpha]);
      else if (ha2)
	dest[alpha] = src2[alpha];

      src1 += b1;
      src2 += b2;
      dest += b2;
    }
}


void
burn_pixels (const guchar *src1,
		const guchar  *src2,
		guchar         *dest,
		gint            length,
		gint            b1,
		gint            b2,
		gint            ha1,
		gint            ha2)
{
  gint alpha, b;
  gint tmp1;

  alpha = (ha1 || ha2) ? MAX (b1, b2) - 1 : b1;

  while (length --)
    {
      for (b = 0; b < alpha; b++)
	{
	    tmp1 = (255 - src1[b]) << 8;
	    tmp1 /= src2[b] + 1;
	    dest[b] = (guchar) CLAMP (255 - tmp1, 0, 255);
	}

      if (ha1 && ha2)
	dest[alpha] = MIN (src1[alpha], src2[alpha]);
      else if (ha2)
	dest[alpha] = src2[alpha];

      src1 += b1;
      src2 += b2;
      dest += b2;
    }
}

void
hardlight_pixels (const guchar *src1,
		  const guchar *src2,
		  guchar       *dest,
		  gint            length,
		  gint            b1,
		  gint            b2,
		  gint            ha1,
		  gint            ha2)
{
  gint alpha, b;
  gint tmp1;

  alpha = (ha1 || ha2) ? MAX (b1, b2) - 1 : b1;

  while (length --)
    {
      for (b = 0; b < alpha; b++)
	{
	  if (src2[b] > 128) {
	    tmp1 = ((gint)255 - src1[b]) * ((gint)255 - ((src2[b] - 128) << 1));
	    dest[b] = (guchar)CLAMP(255 - (tmp1 >> 8), 0, 255);
	  } else {
	    tmp1 = (gint)src1[b] * ((gint)src2[b] << 1);
	    dest[b] = (guchar)CLAMP(tmp1 >> 8, 0, 255);
	  }
	}

      if (ha1 && ha2)
	dest[alpha] = MIN (src1[alpha], src2[alpha]);
      else if (ha2)
	dest[alpha] = src2[alpha];

      src1 += b1;
      src2 += b2;
      dest += b2;
    }
}


MMX_PIXEL_OP_3A_1A(add)

void
add_pixels (const guchar *src1,
	    const guchar *src2,
	    guchar       *dest,
	    gint          length,
	    gint          bytes1,
	    gint          bytes2,
	    gint          has_alpha1,
	    gint          has_alpha2)
{
  gint alpha, b;

  USE_MMX_PIXEL_OP_3A_1A(add)

  alpha = (has_alpha1 || has_alpha2) ? MAX (bytes1, bytes2) - 1 : bytes1;

  while (length --)
    {
      for (b = 0; b < alpha; b++)
	{
	  /* TODO: wouldn't it be better use a 1 dimensional lut ie. add_lut[src1+src2]; */
	  dest[b] = add_lut[(src1[b])] [(src2[b])];
	}

      if (has_alpha1 && has_alpha2)
	dest[alpha] = MIN (src1[alpha], src2[alpha]);
      else if (has_alpha2)
	dest[alpha] = src2[alpha];

      src1 += bytes1;
      src2 += bytes2;
      dest += bytes2;
    }
}


MMX_PIXEL_OP_3A_1A(substract)

void
subtract_pixels (const guchar *src1,
		 const guchar *src2,
		 guchar       *dest,
		 gint          length,
		 gint          bytes1,
		 gint          bytes2,
		 gint          has_alpha1,
		 gint          has_alpha2)
{
  gint alpha, b;
  gint diff;

  USE_MMX_PIXEL_OP_3A_1A(substract)

  alpha = (has_alpha1 || has_alpha2) ? MAX (bytes1, bytes2) - 1 : bytes1;

  while (length --)
    {
      for (b = 0; b < alpha; b++)
	{
	  diff = src1[b] - src2[b];
	  dest[b] = (diff < 0) ? 0 : diff;
	}

      if (has_alpha1 && has_alpha2)
	dest[alpha] = MIN (src1[alpha], src2[alpha]);
      else if (has_alpha2)
	dest[alpha] = src2[alpha];

      src1 += bytes1;
      src2 += bytes2;
      dest += bytes2;
    }
}


MMX_PIXEL_OP_3A_1A(difference)

void
difference_pixels (const guchar *src1,
		   const guchar *src2,
		   guchar       *dest,
		   gint          length,
		   gint          bytes1,
		   gint          bytes2,
		   gint          has_alpha1,
		   gint          has_alpha2)
{
  gint alpha, b;
  gint diff;

  USE_MMX_PIXEL_OP_3A_1A(difference)

  alpha = (has_alpha1 || has_alpha2) ? MAX (bytes1, bytes2) - 1 : bytes1;

  while (length --)
    {
      for (b = 0; b < alpha; b++)
	{
	  diff = src1[b] - src2[b];
	  dest[b] = (diff < 0) ? -diff : diff;
	}

      if (has_alpha1 && has_alpha2)
	dest[alpha] = MIN (src1[alpha], src2[alpha]);
      else if (has_alpha2)
	dest[alpha] = src2[alpha];

      src1 += bytes1;
      src2 += bytes2;
      dest += bytes2;
    }
}


void
dissolve_pixels (const guchar *src,
		 guchar       *dest,
		 gint          x,
		 gint          y,
		 gint          opacity,
		 gint          length,
		 gint          sb,
		 gint          db,
		 gint          has_alpha)
{
  gint alpha, b;
  gint rand_val;
  
#if defined(ENABLE_MP) && defined(__GLIBC__)
  /* The glibc 2.1 documentation recommends using the SVID random functions
   * instead of rand_r
   */
  struct drand48_data seed;
  glong               temp_val;

  srand48_r (random_table[y % RANDOM_TABLE_SIZE], &seed);
  for (b = 0; b < x; b++)
    lrand48_r (&seed, &temp_val);
#elif defined(ENABLE_MP) && !defined(__GLIBC__)
  /* If we are running with multiple threads rand_r give _much_ better
   * performance than rand
   */
  guint seed;
  seed = random_table[y % RANDOM_TABLE_SIZE];
  for (b = 0; b < x; b++)
    rand_r (&seed);
#else
  /* Set up the random number generator */
  srand (random_table[y % RANDOM_TABLE_SIZE]);
  for (b = 0; b < x; b++)
    rand ();
#endif

  alpha = db - 1;

  while (length--)
    {
      /*  preserve the intensity values  */
      for (b = 0; b < alpha; b++)
	dest[b] = src[b];

      /*  dissolve if random value is > opacity  */
#if defined(ENABLE_MP) && defined(__GLIBC__)
      lrand48_r (&seed, &temp_val);
      rand_val = temp_val & 0xff;
#elif defined(ENABLE_MP) && !defined(__GLIBC__)
      rand_val = (rand_r (&seed) & 0xff);
#else
      rand_val = (rand () & 0xff);
#endif
      if (has_alpha)
	dest[alpha] = (rand_val > src[alpha]) ? 0 : src[alpha];
      else
	dest[alpha] = (rand_val > opacity) ? 0 : OPAQUE_OPACITY;

      dest += db;
      src  += sb;
    }
}

void
replace_pixels (guchar   *src1,
		guchar   *src2,
		guchar   *dest,
		guchar   *mask,
		gint      length,
		gint      opacity,
		gboolean *affect,
		gint      bytes1,
		gint      bytes2)
{
  gint    alpha;
  gint    b;
  gdouble a_val, a_recip, mask_val;
  gdouble norm_opacity;
  gint    s1_a, s2_a;
  gint    new_val;

  if (bytes1 != bytes2)
    {
      g_warning ("replace_pixels only works on commensurate pixel regions");
      return;
    }

  alpha = bytes1 - 1;
  norm_opacity = opacity * (1.0 / 65536.0);

  while (length --)
    {
      mask_val = mask[0] * norm_opacity;
      /* calculate new alpha first. */
      s1_a = src1[alpha];
      s2_a = src2[alpha];
      a_val = s1_a + mask_val * (s2_a - s1_a);
 
      if (a_val == 0) /* In any case, write out versions of the blending function */
                      /* that result when combinations of s1_a, s2_a, and         */
	              /* mask_val --> 0 (or mask_val -->1)                        */
        {
          /* Case 1: s1_a, s2_a, AND mask_val all approach 0+:               */
	  /* Case 2: s1_a AND s2_a both approach 0+, regardless of mask_val: */

          if (s1_a + s2_a == 0.0)
            {
              for (b = 0; b < alpha; b++)
	        {
                  new_val = 0.5 + (gdouble) src1[b] + 
		    mask_val * ((gdouble) src2[b] - (gdouble) src1[b]);
 
                  dest[b] = affect[b] ? MIN (new_val, 255) : src1[b];
                }
            }

	  /* Case 3: mask_val AND s1_a both approach 0+, regardless of s2_a  */
          else if (s1_a + mask_val == 0.0)
            {
              for (b = 0; b < alpha; b++)
	        {
                  dest[b] = src1[b]; 
                }
            }

	  /* Case 4: mask_val -->1 AND s2_a -->0, regardless of s1_a         */
          else if (1.0 - mask_val + s2_a == 0.0)
            {
              for (b = 0; b < alpha; b++)
	        {
                  dest[b] = affect[b] ? src2[b] : src1[b]; 
                }
            }
	}
      else
	{
	  a_recip = 1.0 / a_val;
          /* possible optimization: fold a_recip into s1_a and s2_a              */
          for (b = 0; b < alpha; b++)
	    {
	      new_val = 0.5 + a_recip * (src1[b] * s1_a + mask_val *
		 		        (src2[b] * s2_a - src1[b] * s1_a));
	      dest[b] = affect[b] ? MIN (new_val, 255) : src1[b];
            }
        }

      dest[alpha] = affect[alpha] ? a_val + 0.5: s1_a;
      src1 += bytes1;
      src2 += bytes2;
      dest += bytes2;
      mask++;
    }
}

void
swap_pixels (guchar *src,
	     guchar *dest,
	     gint    length)
{
  while (length--)
    {
      *src = *src ^ *dest;
      *dest = *dest ^ *src;
      *src = *src ^ *dest;
      src++;
      dest++;
    }
}

void
scale_pixels (const guchar *src,
	      guchar       *dest,
	      gint          length,
	      gint          scale)
{
  gint tmp;

  while (length --)
    {
      *dest++ = (guchar) INT_MULT (*src, scale, tmp);
      src++;
    }
}

void
add_alpha_pixels (const guchar *src,
		  guchar       *dest,
		  gint          length,
		  gint          bytes)
{
  gint alpha, b;

  alpha = bytes + 1;

  while (length --)
    {
      for (b = 0; b < bytes; b++)
	dest[b] = src[b];

      dest[b] = OPAQUE_OPACITY;

      src += bytes;
      dest += alpha;
    }
}


void
flatten_pixels (const guchar *src,
		guchar       *dest,
		const guchar *bg,
		gint          length,
		gint          bytes)
{
  gint alpha, b;
  gint t1, t2;

  alpha = bytes - 1;
  while (length --)
    {
      for (b = 0; b < alpha; b++)
	dest[b] = INT_MULT (src[b], src[alpha], t1) + 
	          INT_MULT (bg[b], (255 - src[alpha]), t2);

      src += bytes;
      dest += alpha;
    }
}


void
gray_to_rgb_pixels (const guchar *src,
		    guchar       *dest,
		    gint          length,
		    gint          bytes)
{
  gint     b;
  gint     dest_bytes;
  gboolean has_alpha;

  has_alpha = (bytes == 2) ? TRUE : FALSE;
  dest_bytes = (has_alpha) ? 4 : 3;

  while (length --)
    {
      for (b = 0; b < bytes; b++)
	dest[b] = src[0];

      if (has_alpha)
	dest[3] = src[1];

      src += bytes;
      dest += dest_bytes;
    }
}


void
apply_mask_to_alpha_channel (guchar       *src,
			     const guchar *mask,
			     gint          opacity,
			     gint          length,
			     gint          bytes)
{
  glong tmp;

  src += bytes - 1;

  if (opacity == 255)
    {
      while (length --)
	{
	  *src = INT_MULT(*src, *mask, tmp);
	  mask++;
	  src += bytes;
	}
    }
  else
    {
      while (length --)
	{
	  *src = INT_MULT3(*src, *mask, opacity, tmp);
	  mask++;
	  src += bytes;
	}
    }
}


void
combine_mask_and_alpha_channel (guchar       *src,
				const guchar *mask,
				gint          opacity,
				gint          length,
				gint          bytes)
{
  gint mask_val;
  gint alpha;
  gint tmp;

  alpha = bytes - 1;
  src += alpha;

  if (opacity != 255)
    while (length --)
    {
      mask_val = INT_MULT(*mask, opacity, tmp);
      mask++;
      *src = *src + INT_MULT((255 - *src) , mask_val, tmp);
      src += bytes;
    }
  else
    while (length --)
    {
      *src = *src + INT_MULT((255 - *src) , *mask, tmp);
      src += bytes;
      mask++;
    }
}


void
copy_gray_to_inten_a_pixels (const guchar *src,
			     guchar       *dest,
			     gint          length,
			     gint          bytes)
{
  gint b;
  gint alpha;

  alpha = bytes - 1;

  while (length --)
    {
      for (b = 0; b < alpha; b++)
	dest[b] = *src;
      dest[b] = OPAQUE_OPACITY;

      src ++;
      dest += bytes;
    }
}


void
initial_channel_pixels (const guchar *src,
			guchar       *dest,
			gint          length,
			gint          bytes)
{
  gint alpha, b;

  alpha = bytes - 1;

  while (length --)
    {
      for (b = 0; b < alpha; b++)
	dest[b] = src[0];

      dest[alpha] = OPAQUE_OPACITY;

      dest += bytes;
      src ++;
    }
}


void
initial_indexed_pixels (const guchar *src,
			guchar       *dest,
			const guchar *cmap,
			gint          length)
{
  gint col_index;

  /*  This function assumes always that we're mapping from
   *  an RGB colormap to an RGBA image...
   */
  while (length--)
    {
      col_index = *src++ * 3;
      *dest++ = cmap[col_index++];
      *dest++ = cmap[col_index++];
      *dest++ = cmap[col_index++];
      *dest++ = OPAQUE_OPACITY;
    }
}


void
initial_indexed_a_pixels (const guchar *src,
			  guchar       *dest,
			  const guchar *mask,
			  const guchar *cmap,
			  gint          opacity,
			  gint          length)
{
  gint          col_index;
  guchar        new_alpha;
  const guchar *m;
  glong         tmp;

  if (mask)
    m = mask;
  else
    m = &no_mask;

  while (length --)
    {
      col_index = *src++ * 3;
      new_alpha = INT_MULT3(*src, *m, opacity, tmp);
      src++;
      *dest++ = cmap[col_index++];
      *dest++ = cmap[col_index++];
      *dest++ = cmap[col_index++];
      /*  Set the alpha channel  */
      *dest++ = (new_alpha > 127) ? OPAQUE_OPACITY : TRANSPARENT_OPACITY;

      if (mask)
	m++;
    }
}


void
initial_inten_pixels (const guchar *src,
		      guchar       *dest,
		      const guchar *mask,
		      gint          opacity,
		      const gint   *affect,
		      gint          length,
		      gint          bytes)
{
  gint  b;
  gint  tmp;
  gint  l;
  const guchar *m;
  guchar       *destp;
  const guchar *srcp;
  const gint    dest_bytes = bytes + 1;

  if (mask)
  {
    m = mask;
    
    /*  This function assumes the source has no alpha channel and
     *  the destination has an alpha channel.  So dest_bytes = bytes + 1
     */
   
    if (bytes == 3 && affect[0] && affect[1] && affect[2])
      {
	if (!affect[bytes])
	  opacity = 0;
    
	destp = dest + bytes;
	
	if (opacity != 0)
	  while(length--)
	    {
	      dest[0] = src[0];
	      dest[1] = src[1];
	      dest[2] = src[2];
	      dest[3] = INT_MULT(opacity, *m, tmp);
	      src  += bytes;
	      dest += dest_bytes;
	      m++;
	    }
	else
	  while(length--)
	    {
	      dest[0] = src[0];
	      dest[1] = src[1];
	      dest[2] = src[2];
	      dest[3] = opacity;
	      src  += bytes;
	      dest += dest_bytes;
	    }
	return;
      }

    for (b =0; b < bytes; b++)
      {
	destp = dest + b;
	srcp = src + b;
	l = length;

	if (affect[b])
	  while(l--)
	    {
	      *destp = *srcp;
	      srcp  += bytes;
	      destp += dest_bytes;
	    }
	else
	  while(l--)
	    {
	      *destp = 0;
	      destp += dest_bytes;
	    }
      }
    
    /* fill the alpha channel */ 
    if (!affect[bytes])
      opacity = 0;
 
    destp = dest + bytes;
   
    if (opacity != 0)
      while (length--)
	{
	  *destp = INT_MULT(opacity , *m, tmp);
	  destp += dest_bytes;
	  m++;
	}
    else
      while (length--)
	{
	  *destp = opacity;
	  destp += dest_bytes;
	}
  }
  
  /* If no mask */
  else
    {
      m = &no_mask;
      
      /*  This function assumes the source has no alpha channel and
       *  the destination has an alpha channel.  So dest_bytes = bytes + 1
       */
      
      if (bytes == 3 && affect[0] && affect[1] && affect[2])
	{
	  if (!affect[bytes])
	    opacity = 0;

	  destp = dest + bytes;
	  
	  while(length--)
	    {
	      dest[0] = src[0];
	      dest[1] = src[1];
	      dest[2] = src[2];
	      dest[3] = opacity;
	      src  += bytes;
	      dest += dest_bytes;
	    }
	  return;
	}
      
      for (b =0; b < bytes; b++)
	{
	  destp = dest + b;
	  srcp = src + b;
	  l = length;

	  if (affect[b])
	    while(l--)
	      {
		*destp = *srcp;
		srcp  += bytes;
		destp += dest_bytes;
	      }
	  else
	    while(l--)
	      {
		*destp = 0;
		destp += dest_bytes;
	      }
      }
      
      /* fill the alpha channel */ 
      if (!affect[bytes])
	opacity = 0;

      destp = dest + bytes;
    
      while (length--)
	{
	  *destp = opacity;
	  destp += dest_bytes;
	}
    }
}


void
initial_inten_a_pixels (const guchar   *src,
			guchar         *dest,
			const guchar   *mask,
			gint            opacity,
			const gboolean *affect,
			gint            length,
			gint            bytes)
{
  gint          alpha, b;
  const guchar *m;
  glong         tmp;

  alpha = bytes - 1;
  if (mask)
    {
      m = mask;
      while (length --)
	{
	  for (b = 0; b < alpha; b++)
	    dest[b] = src[b] * affect[b];
	  
	  /*  Set the alpha channel  */
	  dest[alpha] = affect [alpha] ? INT_MULT3(opacity, src[alpha], *m, tmp)
	    : 0;
	  
	  m++;
	  
	  dest += bytes;
	  src += bytes;
	}
    }
  else
    {
      while (length --)
	{
	  for (b = 0; b < alpha; b++)
	    dest[b] = src[b] * affect[b];
	  
	  /*  Set the alpha channel  */
	  dest[alpha] = affect [alpha] ? INT_MULT(opacity , src[alpha], tmp) : 0;
	  
	  dest += bytes;
	  src += bytes;
	}
    }
}


void
combine_indexed_and_indexed_pixels (const guchar   *src1,
				    const guchar   *src2,
				    guchar         *dest,
				    const guchar   *mask,
				    gint            opacity,
				    const gboolean *affect,
				    gint            length,
				    gint            bytes)
{
  gint          b;
  guchar        new_alpha;
  const guchar *m;
  gint          tmp;

  if (mask)
    {
      m = mask;
      while (length --)
	{
	  new_alpha = INT_MULT(*m , opacity, tmp);
	  
	  for (b = 0; b < bytes; b++)
	    dest[b] = (affect[b] && new_alpha > 127) ? src2[b] : src1[b];
	  
	  m++;
	  
	  src1 += bytes;
	  src2 += bytes;
	  dest += bytes;
	}
    }
  else
    {
      while (length --)
	{
	  new_alpha = opacity;
	  
	  for (b = 0; b < bytes; b++)
	    dest[b] = (affect[b] && new_alpha > 127) ? src2[b] : src1[b];
	  
	  src1 += bytes;
	  src2 += bytes;
	  dest += bytes;
	}
    }
}


void
combine_indexed_and_indexed_a_pixels (const guchar   *src1,
				      const guchar   *src2,
				      guchar         *dest,
				      const guchar   *mask,
				      gint            opacity,
				      const gboolean *affect,
				      gint            length,
				      gint            bytes)
{
  gint   b, alpha;
  guchar new_alpha;
  gint   src2_bytes;
  glong  tmp;
  const guchar *m;

  alpha = 1;
  src2_bytes = 2;

  if (mask)
    {
      m = mask;
      while (length --)
	{
	  new_alpha = INT_MULT3(src2[alpha], *m, opacity, tmp);

	  for (b = 0; b < bytes; b++)
	    dest[b] = (affect[b] && new_alpha > 127) ? src2[b] : src1[b];

	  m++;

	  src1 += bytes;
	  src2 += src2_bytes;
	  dest += bytes;
	}
    }
  else
    {
      while (length --)
	{
	  new_alpha = INT_MULT(src2[alpha], opacity, tmp);

	  for (b = 0; b < bytes; b++)
	    dest[b] = (affect[b] && new_alpha > 127) ? src2[b] : src1[b];

	  src1 += bytes;
	  src2 += src2_bytes;
	  dest += bytes;
	}
    }
}


void
combine_indexed_a_and_indexed_a_pixels (const guchar   *src1,
					const guchar   *src2,
					guchar         *dest,
					const guchar   *mask,
					gint            opacity,
					const gboolean *affect,
					gint            length,
					gint            bytes)
{
  const guchar * m;
  gint   b, alpha;
  guchar new_alpha;
  glong  tmp;

  alpha = 1;

  if (mask)
    {
      m = mask;
   
      while (length --)
	{
	  new_alpha = INT_MULT3(src2[alpha], *m, opacity, tmp);

	  for (b = 0; b < alpha; b++)
	    dest[b] = (affect[b] && new_alpha > 127) ? src2[b] : src1[b];

	  dest[alpha] = (affect[alpha] && new_alpha > 127) ? 
	    OPAQUE_OPACITY : src1[alpha];

	  m++;

	  src1 += bytes;
	  src2 += bytes;
	  dest += bytes;
	}
    }
  else
    {
      while (length --)
	{
	  new_alpha = INT_MULT(src2[alpha], opacity, tmp);

	  for (b = 0; b < alpha; b++)
	    dest[b] = (affect[b] && new_alpha > 127) ? src2[b] : src1[b];

	  dest[alpha] = (affect[alpha] && new_alpha > 127) ? 
	    OPAQUE_OPACITY : src1[alpha];

	  src1 += bytes;
	  src2 += bytes;
	  dest += bytes;
	}
    }
}


void
combine_inten_a_and_indexed_a_pixels (const guchar *src1,
				      const guchar *src2,
				      guchar       *dest,
				      const guchar *mask,
				      const guchar *cmap,
				      gint          opacity,
				      gint          length,
				      gint          bytes)
{
  gint   b, alpha;
  guchar new_alpha;
  gint   src2_bytes;
  gint   index;
  glong  tmp;
  const guchar *m;

  alpha = 1;
  src2_bytes = 2;

  if (mask)
    {
      m = mask;
 
      while (length --)
	{
	  new_alpha = INT_MULT3(src2[alpha], *m, opacity, tmp);

	  index = src2[0] * 3;

	  for (b = 0; b < bytes-1; b++)
	    dest[b] = (new_alpha > 127) ? cmap[index + b] : src1[b];

	  dest[b] = (new_alpha > 127) ? OPAQUE_OPACITY : src1[b];  
	  /*  alpha channel is opaque  */

	  m++;

	  src1 += bytes;
	  src2 += src2_bytes;
	  dest += bytes;
	}
    }
  else
    {
      while (length --)
	{
	  new_alpha = INT_MULT(src2[alpha], opacity, tmp);

	  index = src2[0] * 3;

	  for (b = 0; b < bytes-1; b++)
	    dest[b] = (new_alpha > 127) ? cmap[index + b] : src1[b];

	  dest[b] = (new_alpha > 127) ? OPAQUE_OPACITY : src1[b];  
	  /*  alpha channel is opaque  */

	  /* m++; /Per */

	  src1 += bytes;
	  src2 += src2_bytes;
	  dest += bytes;
	}
    }
}


void
combine_inten_and_inten_pixels (const guchar   *src1,
				const guchar   *src2,
				guchar         *dest,
				const guchar   *mask,
				gint            opacity,
				const gboolean *affect,
				gint            length,
				gint            bytes)
{
  const guchar * m;
  gint   b;
  guchar new_alpha;
  gint   tmp;

  if (mask)
    {
      m = mask;
      while (length --)
	{
	  new_alpha = INT_MULT(*m, opacity, tmp);

	  for (b = 0; b < bytes; b++)
	    dest[b] = (affect[b]) ?
	      INT_BLEND(src2[b], src1[b], new_alpha, tmp) :
	    src1[b];

	  m++;

	  src1 += bytes;
	  src2 += bytes;
	  dest += bytes;
	}
    }
  else
    {
      while (length --)
	{

	  for (b = 0; b < bytes; b++)
	    dest[b] = (affect[b]) ?
	      INT_BLEND(src2[b], src1[b], opacity, tmp) :
	    src1[b];

	  src1 += bytes;
	  src2 += bytes;
	  dest += bytes;
	}
    }
}


void
combine_inten_and_inten_a_pixels (const guchar   *src1,
				  const guchar   *src2,
				  guchar         *dest,
				  const guchar   *mask,
				  gint            opacity,
				  const gboolean *affect,
				  gint            length,
				  gint            bytes)
{
  gint   alpha, b;
  gint   src2_bytes;
  guchar new_alpha;
  const guchar   *m;
  register glong  t1;

  alpha = bytes;
  src2_bytes = bytes + 1;

  if (mask)
    {
      m = mask;
      while (length --)
	{
	  new_alpha = INT_MULT3(src2[alpha], *m, opacity, t1);

	  for (b = 0; b < bytes; b++)
	    dest[b] = (affect[b]) ?
	      INT_BLEND(src2[b], src1[b], new_alpha, t1) :
	      src1[b];

	  m++;
	  src1 += bytes;
	  src2 += src2_bytes;
	  dest += bytes;
	}
    }
  else
    {
      if (bytes == 3 && affect[0] && affect[1] && affect[2])
	while (length --)
	{
	  new_alpha = INT_MULT(src2[alpha],opacity,t1);
	  dest[0] = INT_BLEND(src2[0] , src1[0] , new_alpha, t1);
	  dest[1] = INT_BLEND(src2[1] , src1[1] , new_alpha, t1);
	  dest[2] = INT_BLEND(src2[2] , src1[2] , new_alpha, t1);
	  src1 += bytes;
	  src2 += src2_bytes;
	  dest += bytes;
	}
      else
	while (length --)
	{
	  new_alpha = INT_MULT(src2[alpha],opacity,t1);
	  for (b = 0; b < bytes; b++)
	    dest[b] = (affect[b]) ?
	      INT_BLEND(src2[b] , src1[b] , new_alpha, t1) :
	    src1[b];

	  src1 += bytes;
	  src2 += src2_bytes;
	  dest += bytes;
	}
    }
}

/*orig #define alphify(src2_alpha,new_alpha) \
	if (new_alpha == 0 || src2_alpha == 0)							\
	  {											\
	    for (b = 0; b < alpha; b++)								\
	      dest[b] = src1 [b];								\
	  }											\
	else if (src2_alpha == new_alpha){							\
	  for (b = 0; b < alpha; b++)								\
	    dest [b] = affect [b] ? src2 [b] : src1 [b];					\
	} else {										\
	  ratio = (float) src2_alpha / new_alpha;						\
	  compl_ratio = 1.0 - ratio;								\
	  											\
	  for (b = 0; b < alpha; b++)								\
	    dest[b] = affect[b] ?								\
	      (guchar) (src2[b] * ratio + src1[b] * compl_ratio + EPSILON) : src1[b];	\
	}*/

/*shortened #define alphify(src2_alpha,new_alpha) \
	if (src2_alpha != 0 && new_alpha != 0)							\
	  {											\
	    if (src2_alpha == new_alpha){							\
	      for (b = 0; b < alpha; b++)							\
	      dest [b] = affect [b] ? src2 [b] : src1 [b];					\
	    } else {										\
	      ratio = (float) src2_alpha / new_alpha;						\
	      compl_ratio = 1.0 - ratio;							\
	  											\
	      for (b = 0; b < alpha; b++)							\
	        dest[b] = affect[b] ?								\
	          (guchar) (src2[b] * ratio + src1[b] * compl_ratio + EPSILON) : src1[b];\
	    }                                                                                   \
	  }*/

#define alphify(src2_alpha,new_alpha) \
	if (src2_alpha != 0 && new_alpha != 0)							\
	  {											\
            b = alpha; \
	    if (src2_alpha == new_alpha){							\
	      do { \
	      b--; dest [b] = affect [b] ? src2 [b] : src1 [b];} while (b);	\
	    } else {										\
	      ratio = (float) src2_alpha / new_alpha;						\
	      compl_ratio = 1.0 - ratio;							\
	  											\
              do { b--; \
	        dest[b] = affect[b] ?								\
	          (guchar) (src2[b] * ratio + src1[b] * compl_ratio + EPSILON) : src1[b];\
         	  } while (b); \
	    }    \
	  }

/*special #define alphify4(src2_alpha,new_alpha) \
	if (src2_alpha != 0 && new_alpha != 0)							\
	  {											\
	    if (src2_alpha == new_alpha){							\
	      dest [0] = affect [0] ? src2 [0] : src1 [0];					\
	      dest [1] = affect [1] ? src2 [1] : src1 [1];					\
	      dest [2] = affect [2] ? src2 [2] : src1 [2];					\
	    } else {										\
	      ratio = (float) src2_alpha / new_alpha;						\
	      compl_ratio = 1.0 - ratio;							\
	  											\
	      dest[0] = affect[0] ?								\
	        (guchar) (src2[0] * ratio + src1[0] * compl_ratio + EPSILON) : src1[0];  \
	      dest[1] = affect[1] ?								\
	        (guchar) (src2[1] * ratio + src1[1] * compl_ratio + EPSILON) : src1[1];  \
	      dest[2] = affect[2] ?								\
	        (guchar) (src2[2] * ratio + src1[2] * compl_ratio + EPSILON) : src1[2];  \
	    }                                                                                   \
	  }*/
	
void
combine_inten_a_and_inten_pixels (const guchar   *src1,
				  const guchar   *src2,
				  guchar         *dest,
				  const guchar   *mask,
				  gint            opacity,
				  const gboolean *affect,
				  gint            mode_affect,  /*  how does the combination mode affect alpha?  */
				  gint            length,
				  gint            bytes)        /*  4 or 2 depending on RGBA or GRAYA  */
{
  gint          alpha, b;
  gint          src2_bytes;
  guchar        src2_alpha;
  guchar        new_alpha;
  const guchar *m;
  gfloat        ratio, compl_ratio;
  glong         tmp;

  src2_bytes = bytes - 1;
  alpha = bytes - 1;

  if (mask)
    {
      m = mask;
      if (opacity == OPAQUE_OPACITY) /* HAS MASK, FULL OPACITY */
	{
	  while (length--)
	    {
	      src2_alpha = *m;
	      new_alpha = src1[alpha] +
		INT_MULT((255 - src1[alpha]), src2_alpha, tmp);
	      alphify (src2_alpha, new_alpha);
	      
	      if (mode_affect)
		{
		  dest[alpha] = (affect[alpha]) ? new_alpha : src1[alpha];
		}
	      else
		{
		  dest[alpha] = (src1[alpha]) ? src1[alpha] :
		    (affect[alpha] ? new_alpha : src1[alpha]);
		}
		
	      m++;
	      src1 += bytes;
	      src2 += src2_bytes;
	      dest += bytes;
	    }
	}
      else /* HAS MASK, SEMI-OPACITY */
	{
	  while (length--)
	    {
	      src2_alpha = INT_MULT(*m, opacity, tmp);
	      new_alpha = src1[alpha] +
		INT_MULT((255 - src1[alpha]), src2_alpha, tmp);
	      alphify (src2_alpha, new_alpha);
	      
	      if (mode_affect)
		{
		  dest[alpha] = (affect[alpha]) ? new_alpha : src1[alpha];
		}
	      else
		{
		  dest[alpha] = (src1[alpha]) ? src1[alpha] :
		    (affect[alpha] ? new_alpha : src1[alpha]);
		}
		
	      m++;
	      src1 += bytes;
	      src2 += src2_bytes;
	      dest += bytes;
	    }
	}
    }
  else /* NO MASK */
    {
      while (length --)
	{
	  src2_alpha = opacity;
	  new_alpha = src1[alpha] +
	    INT_MULT((255 - src1[alpha]), src2_alpha, tmp);
	  alphify (src2_alpha, new_alpha);
	  
	  if (mode_affect)
	    dest[alpha] = (affect[alpha]) ? new_alpha : src1[alpha];
	  else
	    dest[alpha] = (src1[alpha]) ? src1[alpha] : (affect[alpha] ? new_alpha : src1[alpha]);

	    src1 += bytes;
	    src2 += src2_bytes;
	    dest += bytes;
	}
    }
}


void
combine_inten_a_and_inten_a_pixels (const guchar   *src1,
				    const guchar   *src2,
				    guchar         *dest,
				    const guchar   *mask,
				    gint            opacity,
				    const gboolean *affect,
				    const gint      mode_affect,  /*  how does the combination mode affect alpha?  */
				    gint            length,
				    gint            bytes)  /*  4 or 2 depending on RGBA or GRAYA  */
{
  gint b;
  guchar src2_alpha;
  guchar new_alpha;
  const guchar * m;
  gfloat ratio, compl_ratio;
  glong tmp;
  const gint alpha = bytes - 1;

  if (mask)
    {
      m = mask;

      if (opacity == OPAQUE_OPACITY) /* HAS MASK, FULL OPACITY */
	{
	  const gint* mask_ip;
	  gint i,j;

	  if (length >= sizeof(int))
	    {
	      /* HEAD */
	      i =  (((int)m) & (sizeof(int)-1));
	      if (i != 0)
		{
		  i = sizeof(int) - i;
		  length -= i;
		  while (i--)
		    {
		      /* GUTS */
		      src2_alpha = INT_MULT(src2[alpha], *m, tmp);
		      new_alpha = src1[alpha] +
			INT_MULT((255 - src1[alpha]), src2_alpha, tmp);
		  
		      alphify (src2_alpha, new_alpha);
		  
		      if (mode_affect)
			{
			  dest[alpha] = (affect[alpha]) ? new_alpha : src1[alpha];
			}
		      else
			{
			  dest[alpha] = (src1[alpha]) ? src1[alpha] :
			    (affect[alpha] ? new_alpha : src1[alpha]);      
			}
		  
		      m++;
		      src1 += bytes;
		      src2 += bytes;
		      dest += bytes;	
		      /* GUTS END */
		    }
		}

	      /* BODY */
	      mask_ip = (int*)m;
	      i = length / sizeof(int);
	      length %= sizeof(int);
	      while (i--)
		{
		  if (*mask_ip)
		    {
		      m = (const guchar*)mask_ip;
		      j = sizeof(int);
		      while (j--)
			{
			  /* GUTS */
			  src2_alpha = INT_MULT(src2[alpha], *m, tmp);
			  new_alpha = src1[alpha] +
			    INT_MULT((255 - src1[alpha]), src2_alpha, tmp);
		  
			  alphify (src2_alpha, new_alpha);
		  
			  if (mode_affect)
			    {
			      dest[alpha] = (affect[alpha]) ? new_alpha : src1[alpha];
			    }
			  else
			    {
			      dest[alpha] = (src1[alpha]) ? src1[alpha] :
				(affect[alpha] ? new_alpha : src1[alpha]);      
			    }

			  m++;
			  src1 += bytes;
			  src2 += bytes;
			  dest += bytes;
			  /* GUTS END */
			}
		    }
		  else
		    {
		      j = bytes * sizeof(int);
		      src2 += j;
		      while (j--)
			{
			  *(dest++) = *(src1++);
			}
		    }
		  mask_ip++;
		}

	      m = (const guchar*)mask_ip;
	    }

	  /* TAIL */
	  while (length--)
	    {
	      /* GUTS */
	      src2_alpha = INT_MULT(src2[alpha], *m, tmp);
	      new_alpha = src1[alpha] +
		INT_MULT((255 - src1[alpha]), src2_alpha, tmp);
		  
	      alphify (src2_alpha, new_alpha);
		  
	      if (mode_affect)
		{
		  dest[alpha] = (affect[alpha]) ? new_alpha : src1[alpha];
		}
	      else
		{
		  dest[alpha] = (src1[alpha]) ? src1[alpha] :
		    (affect[alpha] ? new_alpha : src1[alpha]);      
		}
		  
	      m++;
	      src1 += bytes;
	      src2 += bytes;
	      dest += bytes;	
	      /* GUTS END */
	    }
	}
      else /* HAS MASK, SEMI-OPACITY */
	{
	  const gint* mask_ip;
	  gint i,j;

	  if (length >= sizeof(int))
	    {
	      /* HEAD */
	      i = (((int)m) & (sizeof(int)-1));
	      if (i != 0)
		{
		  i = sizeof(int) - i;
		  length -= i;
		  while (i--)
		    {
		      /* GUTS */
		      src2_alpha = INT_MULT3(src2[alpha], *m, opacity, tmp);
		      new_alpha = src1[alpha] +
			INT_MULT((255 - src1[alpha]), src2_alpha, tmp);
		  
		      alphify (src2_alpha, new_alpha);
		  
		      if (mode_affect)
			{
			  dest[alpha] = (affect[alpha]) ? new_alpha : src1[alpha];
			}
		      else
			{
			  dest[alpha] = (src1[alpha]) ? src1[alpha] :
			    (affect[alpha] ? new_alpha : src1[alpha]);
			}
		  
		      m++;
		      src1 += bytes;
		      src2 += bytes;
		      dest += bytes;
		      /* GUTS END */
		    }
		}
	  
	      /* BODY */
	      mask_ip = (int*)m;
	      i = length / sizeof(int);
	      length %= sizeof(int);
	      while (i--)
		{
		  if (*mask_ip)
		    {
		      m = (const guchar*)mask_ip;
		      j = sizeof(int);
		      while (j--)
			{
			  /* GUTS */
			  src2_alpha = INT_MULT3(src2[alpha], *m, opacity, tmp);
			  new_alpha = src1[alpha] +
			    INT_MULT((255 - src1[alpha]), src2_alpha, tmp);
		      
			  alphify (src2_alpha, new_alpha);
		      
			  if (mode_affect)
			    {
			      dest[alpha] = (affect[alpha]) ? new_alpha : src1[alpha];
			    }
			  else
			    {
			      dest[alpha] = (src1[alpha]) ? src1[alpha] :
				(affect[alpha] ? new_alpha : src1[alpha]);
			    }

			  m++;
			  src1 += bytes;
			  src2 += bytes;
			  dest += bytes;
			  /* GUTS END */
			}
		    }
		  else
		    {
		      j = bytes * sizeof(int);
		      src2 += j;
		      while (j--)
			{
			  *(dest++) = *(src1++);
			}
		    }
		  mask_ip++;
		}

	      m = (const guchar*)mask_ip;
	    }
	
	  /* TAIL */
	  while (length--)
	    {
	      /* GUTS */
	      src2_alpha = INT_MULT3(src2[alpha], *m, opacity, tmp);
	      new_alpha = src1[alpha] +
		INT_MULT((255 - src1[alpha]), src2_alpha, tmp);
	      
	      alphify (src2_alpha, new_alpha);
	      
	      if (mode_affect)
		{
		  dest[alpha] = (affect[alpha]) ? new_alpha : src1[alpha];
		}
	      else
		{
		  dest[alpha] = (src1[alpha]) ? src1[alpha] :
		    (affect[alpha] ? new_alpha : src1[alpha]);
		}
	      
	      m++;
	      src1 += bytes;
	      src2 += bytes;
	      dest += bytes;
	      /* GUTS END */
	    }
	}
    }
  else
    {
      if (opacity == OPAQUE_OPACITY) /* NO MASK, FULL OPACITY */
	{
	  while (length --)
	    {
	      src2_alpha = src2[alpha];
	      new_alpha = src1[alpha] +
		INT_MULT((255 - src1[alpha]), src2_alpha, tmp);
	      
	      alphify (src2_alpha, new_alpha);
	      
	      if (mode_affect)
		{
		  dest[alpha] = (affect[alpha]) ? new_alpha : src1[alpha];
		}
	      else
		{
		  dest[alpha] = (src1[alpha]) ? src1[alpha] :
		    (affect[alpha] ? new_alpha : src1[alpha]);
		}
		
	      src1 += bytes;
	      src2 += bytes;
	      dest += bytes;
	    }
	}
      else /* NO MASK, SEMI OPACITY */
	{
	  while (length --)
	    {
	      src2_alpha = INT_MULT(src2[alpha], opacity, tmp);
	      new_alpha = src1[alpha] +
		INT_MULT((255 - src1[alpha]), src2_alpha, tmp);
	      
	      alphify (src2_alpha, new_alpha);
	      
	      if (mode_affect)
		{
		  dest[alpha] = (affect[alpha]) ? new_alpha : src1[alpha];
		}
	      else
		{
		  dest[alpha] = (src1[alpha]) ? src1[alpha] :
		    (affect[alpha] ? new_alpha : src1[alpha]);
		}
		
	      src1 += bytes;
	      src2 += bytes;
	      dest += bytes;	  
	    }
	}
    }
}
#undef alphify

void
combine_inten_a_and_channel_mask_pixels (const guchar *src,
					 const guchar *channel,
					 guchar       *dest,
					 const guchar *col,
					 gint          opacity,
					 gint          length,
					 gint          bytes)
{
  gint   alpha, b;
  guchar channel_alpha;
  guchar new_alpha;
  guchar compl_alpha;
  gint   t, s;

  alpha = bytes - 1;
  while (length --)
    {
      channel_alpha = INT_MULT (255 - *channel, opacity, t);
      if (channel_alpha)
	{
	  new_alpha = src[alpha] + INT_MULT ((255 - src[alpha]), channel_alpha, t);

	  if (new_alpha != 255)
	    channel_alpha = (channel_alpha * 255) / new_alpha;
	  compl_alpha = 255 - channel_alpha;

	  for (b = 0; b < alpha; b++)
	    dest[b] = INT_MULT (col[b], channel_alpha, t) +
	      INT_MULT (src[b], compl_alpha, s);
	  dest[b] = new_alpha;
	}
      else
	memcpy(dest, src, bytes);

      /*  advance pointers  */
      src+=bytes;
      dest+=bytes;
      channel++;
    }
}


void
combine_inten_a_and_channel_selection_pixels (const guchar *src,
					      const guchar *channel,
					      guchar       *dest,
					      const guchar *col,
					      gint          opacity,
					      gint          length,
					      gint          bytes)
{
  gint   alpha, b;
  guchar channel_alpha;
  guchar new_alpha;
  guchar compl_alpha;
  gint   t, s;

  alpha = bytes - 1;
  while (length --)
    {
      channel_alpha = INT_MULT (*channel, opacity, t);
      if (channel_alpha)
	{
	  new_alpha = src[alpha] + INT_MULT ((255 - src[alpha]), channel_alpha, t);

	  if (new_alpha != 255)
	    channel_alpha = (channel_alpha * 255) / new_alpha;
	  compl_alpha = 255 - channel_alpha;

	  for (b = 0; b < alpha; b++)
	    dest[b] = INT_MULT (col[b], channel_alpha, t) +
	      INT_MULT (src[b], compl_alpha, s);
	  dest[b] = new_alpha;
	}
      else
	memcpy(dest, src, bytes);

      /*  advance pointers  */
      src+=bytes;
      dest+=bytes;
      channel++;
    }
}


void
behind_inten_pixels (const guchar   *src1,
		     const guchar   *src2,
		     guchar         *dest,
		     const guchar   *mask,
		     gint            opacity,
		     const gboolean *affect,
		     gint            length,
		     gint            bytes1,
		     gint            bytes2,
		     gint            has_alpha1,
		     gint            has_alpha2)
{
  gint          alpha, b;
  guchar        src1_alpha;
  guchar        src2_alpha;
  guchar        new_alpha;
  const guchar *m;
  gfloat        ratio, compl_ratio;
  glong         tmp;

  if (mask)
    m = mask;
  else
    m = &no_mask;

  /*  the alpha channel  */
  alpha = bytes1 - 1;

  while (length --)
    {
      src1_alpha = src1[alpha];
      src2_alpha = INT_MULT3(src2[alpha], *m, opacity, tmp);
      new_alpha = src2_alpha +
	INT_MULT((255 - src2_alpha), src1_alpha, tmp);
      if (new_alpha)
	ratio = (float) src1_alpha / new_alpha;
      else
	ratio = 0.0;
      compl_ratio = 1.0 - ratio;

      for (b = 0; b < alpha; b++)
	dest[b] = (affect[b]) ?
	  (guchar) (src1[b] * ratio + src2[b] * compl_ratio + EPSILON) :
	src1[b];

      dest[alpha] = (affect[alpha]) ? new_alpha : src1[alpha];

      if (mask)
	m++;

      src1 += bytes1;
      src2 += bytes2;
      dest += bytes1;
    }
}


void
behind_indexed_pixels (const guchar   *src1,
		       const guchar   *src2,
		       guchar         *dest,
		       const guchar   *mask,
		       gint            opacity,
		       const gboolean *affect,
		       gint            length,
		       gint            bytes1,
		       gint            bytes2,
		       gint            has_alpha1,
		       gint            has_alpha2)
{
  gint          alpha, b;
  guchar        src1_alpha;
  guchar        src2_alpha;
  guchar        new_alpha;
  const guchar *m;
  glong         tmp;

  if (mask)
    m = mask;
  else
    m = &no_mask;

  /*  the alpha channel  */
  alpha = bytes1 - 1;

  while (length --)
    {
      src1_alpha = src1[alpha];
      src2_alpha = INT_MULT3(src2[alpha], *m, opacity, tmp);
      new_alpha = (src2_alpha > 127) ? OPAQUE_OPACITY : TRANSPARENT_OPACITY;

      for (b = 0; b < bytes1; b++)
	dest[b] = (affect[b] && new_alpha == OPAQUE_OPACITY && (src1_alpha > 127)) ?
	  src2[b] : src1[b];

      if (mask)
	m++;

      src1 += bytes1;
      src2 += bytes2;
      dest += bytes1;
    }
}


void
replace_inten_pixels (const guchar   *src1,
		      const guchar   *src2,
		      guchar         *dest,
		      const guchar   *mask,
		      gint            opacity,
		      const gboolean *affect,
		      gint            length,
		      gint            bytes1,
		      gint            bytes2,
		      gint            has_alpha1,
		      gint            has_alpha2)
{
  gint  b;
  gint  tmp;
  const gint bytes = MIN (bytes1, bytes2);

  if (mask)
    {
      guchar        mask_alpha;
      const guchar *m = mask;

      while (length --)
        {
	  mask_alpha = INT_MULT(*m, opacity, tmp);
	  
	  for (b = 0; b < bytes; b++)
	    dest[b] = (affect[b]) ?
	      INT_BLEND(src2[b], src1[b], mask_alpha, tmp) :
	      src1[b];

	  if (has_alpha1 && !has_alpha2)
	    dest[b] = src1[b];

	  m++;

	  src1 += bytes1;
	  src2 += bytes2;
	  dest += bytes1;
	}
    }
  else
    {
      static const guchar mask_alpha = OPAQUE_OPACITY ;

      while (length --)
        {
	  for (b = 0; b < bytes; b++)
	    dest[b] = (affect[b]) ?
	      INT_BLEND(src2[b], src1[b], mask_alpha, tmp) :
	      src1[b];

	  if (has_alpha1 && !has_alpha2)
	    dest[b] = src1[b];

	  src1 += bytes1;
	  src2 += bytes2;
	  dest += bytes1;
	}
    }
}


void
replace_indexed_pixels (const guchar   *src1,
			const guchar   *src2,
			guchar         *dest,
			const guchar   *mask,
			gint            opacity,
			const gboolean *affect,
			gint            length,
			gint            bytes1,
			gint            bytes2,
			gint            has_alpha1,
			gint            has_alpha2)
{
  gint          bytes, b;
  guchar        mask_alpha;
  const guchar *m;
  gint          tmp;

  if (mask)
    m = mask;
  else
    m = &no_mask;

  bytes = MIN (bytes1, bytes2);
  while (length --)
    {
      mask_alpha = INT_MULT(*m, opacity, tmp);

      for (b = 0; b < bytes; b++)
	dest[b] = (affect[b] && mask_alpha) ? src2[b] : src1[b];

      if (has_alpha1 && !has_alpha2)
	dest[b] = src1[b];

      if (mask)
	m++;

      src1 += bytes1;
      src2 += bytes2;
      dest += bytes1;
    }
}


void
erase_inten_pixels (const guchar   *src1,
		    const guchar   *src2,
		    guchar         *dest,
		    const guchar   *mask,
		    gint            opacity,
		    const gboolean *affect,
		    gint            length,
		    gint            bytes)
{
  gint       b;
  guchar     src2_alpha;
  glong      tmp;
  const gint alpha = bytes - 1;

  if (mask)
    {
      const guchar *m = mask;
 
      while (length --)
        {
	  for (b = 0; b < alpha; b++)
	    dest[b] = src1[b];

	  src2_alpha = INT_MULT3(src2[alpha], *m, opacity, tmp);
	  dest[alpha] = src1[alpha] - INT_MULT(src1[alpha], src2_alpha, tmp);

	  m++;

	  src1 += bytes;
	  src2 += bytes;
	  dest += bytes;
	}
    }
  else
    {
      guchar *m = &no_mask;

      while (length --)
        {
	  for (b = 0; b < alpha; b++)
	    dest[b] = src1[b];

	  src2_alpha = INT_MULT3(src2[alpha], *m, opacity, tmp);
	  dest[alpha] = src1[alpha] - INT_MULT(src1[alpha], src2_alpha, tmp);

	  src1 += bytes;
	  src2 += bytes;
	  dest += bytes;
	}
    }
}


void
erase_indexed_pixels (const guchar   *src1,
		      const guchar   *src2,
		      guchar         *dest,
		      const guchar   *mask,
		      gint            opacity,
		      const gboolean *affect,
		      gint            length,
		      gint            bytes)
{
  gint          alpha, b;
  guchar        src2_alpha;
  const guchar *m;
  glong         tmp;

  if (mask)
    m = mask;
  else
    m = &no_mask;

  alpha = bytes - 1;
  while (length --)
    {
      for (b = 0; b < alpha; b++)
	dest[b] = src1[b];

      src2_alpha = INT_MULT3(src2[alpha], *m, opacity, tmp);
      dest[alpha] = (src2_alpha > 127) ? TRANSPARENT_OPACITY : src1[alpha];

      if (mask)
	m++;

      src1 += bytes;
      src2 += bytes;
      dest += bytes;
    }
}

void
anti_erase_inten_pixels (const guchar   *src1,
			 const guchar   *src2,
			 guchar         *dest,
			 const guchar   *mask,
			 gint            opacity,
			 const gboolean *affect,
			 gint            length,
			 gint            bytes)
{
  gint          alpha, b;
  guchar        src2_alpha;
  const guchar *m;
  glong         tmp;

  if (mask)
    m = mask;
  else
    m = &no_mask;

  alpha = bytes - 1;
  while (length --)
    {
      for (b = 0; b < alpha; b++)
	dest[b] = src1[b];

      src2_alpha = INT_MULT3(src2[alpha], *m, opacity, tmp);
      dest[alpha] = src1[alpha] + INT_MULT((255 - src1[alpha]), src2_alpha, tmp);

      if (mask)
	m++;

      src1 += bytes;
      src2 += bytes;
      dest += bytes;
    }
}

void
anti_erase_indexed_pixels (const guchar   *src1,
			   const guchar   *src2,
			   guchar         *dest,
			   const guchar   *mask,
			   gint            opacity,
			   const gboolean *affect,
			   gint            length,
			   gint            bytes)
{
  gint          alpha, b;
  guchar        src2_alpha;
  const guchar *m;
  glong         tmp;

  if (mask)
    m = mask;
  else
    m = &no_mask;

  alpha = bytes - 1;
  while (length --)
    {
      for (b = 0; b < alpha; b++)
	dest[b] = src1[b];

      src2_alpha = INT_MULT3(src2[alpha], *m, opacity, tmp);
      dest[alpha] = (src2_alpha > 127) ? OPAQUE_OPACITY : src1[alpha];

      if (mask)
	m++;

      src1 += bytes;
      src2 += bytes;
      dest += bytes;
    }
}


void
extract_from_inten_pixels (guchar       *src,
			   guchar       *dest,
			   const guchar *mask,
			   const guchar *bg,
			   gint          cut,
			   gint          length,
			   gint          bytes,
			   gint          has_alpha)
{
  gint          b, alpha;
  gint          dest_bytes;
  const guchar *m;
  gint          tmp;

  if (mask)
    m = mask;
  else
    m = &no_mask;

  alpha = (has_alpha) ? bytes - 1 : bytes;
  dest_bytes = (has_alpha) ? bytes : bytes + 1;
  while (length --)
    {
      for (b = 0; b < alpha; b++)
	dest[b] = src[b];

      if (has_alpha)
	{
	  dest[alpha] = INT_MULT(*m, src[alpha], tmp);
	  if (cut)
	    src[alpha] = INT_MULT((255 - *m), src[alpha], tmp);
	}
      else
	{
	  dest[alpha] = *m;
	  if (cut)
	    for (b = 0; b < bytes; b++)
	      src[b] = INT_BLEND(bg[b], src[b], *m, tmp);
	}

      if (mask)
	m++;

      src += bytes;
      dest += dest_bytes;
    }
}


void
extract_from_indexed_pixels (guchar       *src,
			     guchar       *dest,
			     const guchar *mask,
			     const guchar *cmap,
			     const guchar *bg,
			     gint          cut,
			     gint          length,
			     gint          bytes,
			     gint          has_alpha)
{
  gint          b;
  gint          index;
  const guchar *m;
  gint          t;

  if (mask)
    m = mask;
  else
    m = &no_mask;

  while (length --)
    {
      index = src[0] * 3;
      for (b = 0; b < 3; b++)
	dest[b] = cmap[index + b];

      if (has_alpha)
	{
	  dest[3] = INT_MULT (*m, src[1], t);
	  if (cut)
	    src[1] = INT_MULT ((255 - *m), src[1], t);
	}
      else
	{
	  dest[3] = *m;
	  if (cut)
	    src[0] = (*m > 127) ? bg[0] : src[0];
	}

      if (mask)
	m++;

      src += bytes;
      dest += 4;
    }
}


void
map_to_color (gint          src_type,
	      const guchar *cmap,
	      const guchar *src,
	      guchar       *rgb)
{
  switch (src_type)
    {
    case 0:  /*  RGB      */
      /*  Straight copy  */
      *rgb++ = *src++;
      *rgb++ = *src++;
      *rgb   = *src;
      break;
    case 1:  /*  GRAY     */
      *rgb++ = *src;
      *rgb++ = *src;
      *rgb   = *src;
      break;
    case 2:  /*  INDEXED  */
      {
	gint index = *src * 3;
	*rgb++ = cmap [index++];
	*rgb++ = cmap [index++];
	*rgb   = cmap [index++];
      }
      break;
    }
}


gint
map_rgb_to_indexed (const guchar    *cmap,
		    gint             num_cols,
		    const GimpImage *gimage,
		    gint             r,
		    gint             g,
		    gint             b)
{
  guint pixel;
  gint  hash_index;
  gint  cmap_index;

  pixel = (r << 16) | (g << 8) | b;
  hash_index = pixel % HASH_TABLE_SIZE;

  /*  Hash table lookup hit  */
  if (color_hash_table[hash_index].gimage == gimage &&
      color_hash_table[hash_index].pixel == pixel)
    {
      cmap_index = color_hash_table[hash_index].index;
      color_hash_hits++;
    }
  /*  Hash table lookup miss  */
  else
    {
      const guchar *col;
      gint          diff, sum, max;
      gint          i;

      max = MAXDIFF;
      cmap_index = 0;

      col = cmap;
      for (i = 0; i < num_cols; i++)
	{
	  diff = r - *col++;
	  sum = diff * diff;
	  diff = g - *col++;
	  sum += diff * diff;
	  diff = b - *col++;
	  sum += diff * diff;

	  if (sum < max)
	    {
	      cmap_index = i;
	      max = sum;
	    }
	}

      /*  update the hash table  */
      color_hash_table[hash_index].pixel  = pixel;
      color_hash_table[hash_index].index  = cmap_index;
      color_hash_table[hash_index].gimage = (GimpImage *) gimage;
      color_hash_misses++;
    }

  return cmap_index;
}



/**************************************************/
/*    REGION FUNCTIONS                            */
/**************************************************/

void
color_region (PixelRegion  *dest,
	      const guchar *col)
{
  gint    h;
  guchar *s;
  void   *pr;

  for (pr = pixel_regions_register (1, dest);
       pr != NULL;
       pr = pixel_regions_process (pr))
    {
      h = dest->h;
      s = dest->data;

      if (dest->w*dest->bytes == dest->rowstride)
	{
	  /* do it all in one function call if we can */
	  /* this hasn't been tested to see if it is a
	     signifigant speed gain yet */
	  color_pixels (s, col, dest->w*h, dest->bytes);
	}
      else
	{
	  while (h--)
	    {
	      color_pixels (s, col, dest->w, dest->bytes);
	      s += dest->rowstride;
	    }
	}
    }
}


void
blend_region (PixelRegion *src1,
	      PixelRegion *src2,
	      PixelRegion *dest,
	      gint         blend)
{
  gint    h;
  guchar *s1, *s2, * d;
  void   *pr;

  for (pr = pixel_regions_register (3, src1, src2, dest);
       pr != NULL;
       pr = pixel_regions_process (pr))
    {
      s1 = src1->data;
      s2 = src2->data;
      d = dest->data;
      h = src1->h;

      while (h --)
	{
          blend_pixels (s1, s2, d, blend, src1->w, src1->bytes, FALSE);
	  s1 += src1->rowstride;
	  s2 += src2->rowstride;
	  d += dest->rowstride;
	}
    }
}


void
shade_region (PixelRegion *src,
	      PixelRegion *dest,
	      guchar      *col,
	      gint         blend)
{
  gint    h;
  guchar *s, * d;

  s = src->data;
  d = dest->data;
  h = src->h;

  while (h --)
    {
/*      blend_pixels (s, d, col, blend, src->w, src->bytes);*/
      s += src->rowstride;
      d += dest->rowstride;
    }
}


void
copy_region (PixelRegion *src,
	     PixelRegion *dest)
{
  gint    h;
  gint    pixelwidth;
  guchar *s, *d;
  void   *pr;

#ifdef COWSHOW
  fputc ('[',stderr);
#endif
  for (pr = pixel_regions_register (2, src, dest);
       pr != NULL;
       pr = pixel_regions_process (pr))
    {
      if (src->tiles && dest->tiles &&
	  src->curtile && dest->curtile &&
	  src->offx == 0 && dest->offx == 0 &&
	  src->offy == 0 && dest->offy == 0 &&
	  src->w  == tile_ewidth (src->curtile)  && 
	  dest->w == tile_ewidth (dest->curtile) &&
	  src->h  == tile_eheight (src->curtile) && 
	  dest->h == tile_eheight (dest->curtile)) 
	{
#ifdef COWSHOW
	  fputc('!',stderr);
#endif
	  tile_manager_map_over_tile (dest->tiles, dest->curtile, src->curtile);
	}
      else 
	{
#ifdef COWSHOW
	  fputc ('.',stderr);
#endif
	  pixelwidth = src->w * src->bytes;
	  s = src->data;
	  d = dest->data;
	  h = src->h;
	  
	  while (h --)
	    {
	      memcpy (d, s, pixelwidth);
	      s += src->rowstride;
	      d += dest->rowstride;
	    }
	}
    }

#ifdef COWSHOW
  fputc (']',stderr);
  fputc ('\n',stderr);
#endif
}


void
add_alpha_region (PixelRegion *src,
		  PixelRegion *dest)
{
  gint    h;
  guchar *s, *d;
  void   *pr;

  for (pr = pixel_regions_register (2, src, dest);
       pr != NULL;
       pr = pixel_regions_process (pr))
    {
      s = src->data;
      d = dest->data;
      h = src->h;

      while (h --)
	{
	  add_alpha_pixels (s, d, src->w, src->bytes);
	  s += src->rowstride;
	  d += dest->rowstride;
	}
    }
}


void
flatten_region (PixelRegion *src,
		PixelRegion *dest,
		guchar      *bg)
{
  gint    h;
  guchar *s, *d;

  s = src->data;
  d = dest->data;
  h = src->h;

  while (h --)
    {
      flatten_pixels (s, d, bg, src->w, src->bytes);
      s += src->rowstride;
      d += dest->rowstride;
    }
}


void
extract_alpha_region (PixelRegion *src,
		      PixelRegion *mask,
		      PixelRegion *dest)
{
  gint h;
  guchar * s, * m, * d;
  void * pr;

  for (pr = pixel_regions_register (3, src, mask, dest); pr != NULL; pr = pixel_regions_process (pr))
    {
      s = src->data;
      d = dest->data;
      if (mask)
	m = mask->data;
      else
	m = NULL;

      h = src->h;
      while (h --)
	{
	  extract_alpha_pixels (s, m, d, src->w, src->bytes);
	  s += src->rowstride;
	  d += dest->rowstride;
	  if (mask)
	    m += mask->rowstride;
	}
    }
}


void
extract_from_region (PixelRegion *src,
		     PixelRegion *dest,
		     PixelRegion *mask,
		     guchar      *cmap,
		     guchar      *bg,
		     gint         type,
		     gint         has_alpha,
		     gint         cut)
{
  gint    h;
  guchar *s, *d, *m;
  void   *pr;

  for (pr = pixel_regions_register (3, src, dest, mask);
       pr != NULL;
       pr = pixel_regions_process (pr))
    {
      s = src->data;
      d = dest->data;
      m = (mask) ? mask->data : NULL;
      h = src->h;

      while (h --)
	{
	  switch (type)
	    {
	    case 0:  /*  RGB      */
	    case 1:  /*  GRAY     */
	      extract_from_inten_pixels (s, d, m, bg, cut, src->w,
					 src->bytes, has_alpha);
	      break;
	    case 2:  /*  INDEXED  */
	      extract_from_indexed_pixels (s, d, m, cmap, bg, cut, src->w,
					   src->bytes, has_alpha);
	      break;
	    }

	  s += src->rowstride;
	  d += dest->rowstride;
	  if (mask)
	    m += mask->rowstride;
	}
    }
}


void
convolve_region (PixelRegion	*srcR,
		 PixelRegion	*destR,
		 gint		*matrix,
		 gint		 size,
		 gint		 divisor,
		 ConvolutionType mode)
{
  /*  Convolve the src image using the convolution matrix, writing to dest  */
  /*  Convolve is not tile-enabled--use accordingly  */
  guchar *src, *s_row, *s;
  guchar *dest, *d;
  gint   *m;
  gint    total [4];
  gint    b, bytes;
  gint    length;
  gint    wraparound;
  gint    margin;      /*  margin imposed by size of conv. matrix  */
  gint    i, j;
  gint    x, y;
  gint    offset;

  /*  If the mode is NEGATIVE_CONVOL, the offset should be 128  */
  if (mode == NEGATIVE_CONVOL)
    {
      offset = 128;
      mode = NORMAL_CONVOL;
    }
  else
    offset = 0;

  /*  check for the boundary cases  */
  if (srcR->w < (size - 1) || srcR->h < (size - 1))
    return;

  /*  Initialize some values  */
  bytes = srcR->bytes;
  length = bytes * srcR->w;
  margin = size / 2;
  src = srcR->data;
  dest = destR->data;

  /*  calculate the source wraparound value  */
  wraparound = srcR->rowstride - size * bytes;

  /* copy the first (size / 2) scanlines of the src image... */
  for (i = 0; i < margin; i++)
    {
      memcpy (dest, src, length);
      src += srcR->rowstride;
      dest += destR->rowstride;
    }

  src = srcR->data;

  for (y = margin; y < srcR->h - margin; y++)
    {
      s_row = src;
      s = s_row + srcR->rowstride*margin;
      d = dest;

      /* handle the first margin pixels... */
      b = bytes * margin;
      while (b --)
	*d++ = *s++;

      /* now, handle the center pixels */
      x = srcR->w - margin*2;
      while (x--)
	{
	  s = s_row;

	  m = matrix;
	  total [0] = total [1] = total [2] = total [3] = 0;
	  i = size;
	  while (i --)
	    {
	      j = size;
	      while (j --)
		{
		  for (b = 0; b < bytes; b++)
		    total [b] += *m * *s++;
		  m ++;
		}

	      s += wraparound;
	    }

	  for (b = 0; b < bytes; b++)
	    {
	      total [b] = total [b] / divisor + offset;

	      if (total [b] < 0 && mode != NORMAL_CONVOL)
		total [b] = - total [b];

	      if (total [b] < 0)
		*d++ = 0;
	      else
		*d++ = (total [b] > 255) ? 255 : (guchar) total [b];
	    }

	  s_row += bytes;

	}

      /* handle the last pixel... */
      s = s_row + (srcR->rowstride + bytes) * margin;
      b = bytes * margin;
      while (b --)
	*d++ = *s++;

      /* set the memory pointers */
      src += srcR->rowstride;
      dest += destR->rowstride;
    }

  src += srcR->rowstride*margin;

  /* copy the last (margin) scanlines of the src image... */
  for (i = 0; i < margin; i++)
    {
      memcpy (dest, src, length);
      src += srcR->rowstride;
      dest += destR->rowstride;
    }
}

/* Convert from separated alpha to premultiplied alpha. Only works on
   non-tiled regions! */
void
multiply_alpha_region (PixelRegion *srcR)
{
  guchar  *src, *s;
  gint     x, y;
  gint     width, height;
  gint     b, bytes;
  gdouble  alpha_val;

  width = srcR->w;
  height = srcR->h;
  bytes = srcR->bytes;

  src = srcR->data;

  for (y = 0; y < height; y++)
    {
      s = src;
      for (x = 0; x < width; x++)
	{
	  alpha_val = s[bytes - 1] * (1.0 / 255.0);
	  for (b = 0; b < bytes - 1; b++)
	    s[b] = 0.5 + s[b] * alpha_val;
	  s += bytes;
	}
      src += srcR->rowstride;
    }
}

/* Convert from premultiplied alpha to separated alpha. Only works on
   non-tiled regions! */
void
separate_alpha_region (PixelRegion *srcR)
{
  guchar  *src, *s;
  gint     x, y;
  gint     width, height;
  gint     b, bytes;
  gdouble  alpha_recip;
  gint     new_val;

  width = srcR->w;
  height = srcR->h;
  bytes = srcR->bytes;

  src = srcR->data;

  for (y = 0; y < height; y++)
    {
      s = src;
      for (x = 0; x < width; x++)
	{
	  /* predicate is equivalent to:
	     (((s[bytes - 1] - 1) & 255) + 2) & 256
	     */
	  if (s[bytes - 1] != 0 && s[bytes - 1] != 255)
	    {
	      alpha_recip = 255.0 / s[bytes - 1];
	      for (b = 0; b < bytes - 1; b++)
		{
		  new_val = 0.5 + s[b] * alpha_recip;
		  new_val = MIN (new_val, 255);
		  s[b] = new_val;
		}
	    }
	  s += bytes;
	}
      src += srcR->rowstride;
    }
}

void
gaussian_blur_region (PixelRegion *srcR,
		      gdouble      radius_x,
		      gdouble      radius_y)
{
  gdouble std_dev;
  glong   width, height;
  gint    bytes;
  guchar *src, *sp;
  guchar *dest, *dp;
  guchar *data;
  gint   *buf, *b;
  gint    pixels;
  gint    total;
  gint    i, row, col;
  gint    start, end;
  gint   *curve;
  gint   *sum;
  gint    val;
  gint    length;
  gint    alpha;
  gint    initial_p, initial_m;

  if (radius_x == 0.0 && radius_y == 0.0) return;    /* zero blur is a no-op */

  /*  allocate the result buffer  */
  length = MAX (srcR->w, srcR->h) * srcR->bytes;
  data = paint_funcs_get_buffer (length * 2);
  src = data;
  dest = data + length;

  width = srcR->w;
  height = srcR->h;
  bytes = srcR->bytes;
  alpha = bytes - 1;

  buf = g_malloc (sizeof (int) * MAX (width, height) * 2);

  if (radius_y != 0.0)
    {
      std_dev = sqrt (-(radius_y * radius_y) / (2 * log (1.0 / 255.0)));
      curve = make_curve (std_dev, &length);
      sum = g_malloc (sizeof (int) * (2 * length + 1));
      sum[0] = 0;

      for (i = 1; i <= length*2; i++)
	sum[i] = curve[i-length-1] + sum[i-1];
      sum += length;

      total = sum[length] - sum[-length];

      for (col = 0; col < width; col++)
	{
	  pixel_region_get_col (srcR, col + srcR->x, srcR->y, height, src, 1);
	  sp = src + alpha;

	  initial_p = sp[0];
	  initial_m = sp[(height-1) * bytes];

	  /*  Determine a run-length encoded version of the column  */
	  run_length_encode (sp, buf, height, bytes);

	  for (row = 0; row < height; row++)
	    {
	      start = (row < length) ? -row : -length;
	      end = (height <= (row + length)) ? (height - row - 1) : length;

	      val = 0;
	      i = start;
	      b = buf + (row + i) * 2;

	      if (start != -length)
		val += initial_p * (sum[start] - sum[-length]);

	      while (i < end)
		{
		  pixels = b[0];
		  i += pixels;
		  if (i > end)
		    i = end;
		  val += b[1] * (sum[i] - sum[start]);
		  b += (pixels * 2);
		  start = i;
		}

	      if (end != length)
		val += initial_m * (sum[length] - sum[end]);

	      sp[row * bytes] = val / total;
	    }

	  pixel_region_set_col (srcR, col + srcR->x, srcR->y, height, src);
	}

      g_free (sum - length);
      g_free (curve - length);
    }

  if (radius_x != 0.0)
    {
      std_dev = sqrt (-(radius_x * radius_x) / (2 * log (1.0 / 255.0)));
      curve = make_curve (std_dev, &length);
      sum = g_malloc (sizeof (int) * (2 * length + 1));
      sum[0] = 0;

      for (i = 1; i <= length*2; i++)
	sum[i] = curve[i-length-1] + sum[i-1];
      sum += length;

      total = sum[length] - sum[-length];

      for (row = 0; row < height; row++)
	{
	  pixel_region_get_row (srcR, srcR->x, row + srcR->y, width, src, 1);
	  sp = src + alpha;
	  dp = dest + alpha;

	  initial_p = sp[0];
	  initial_m = sp[(width-1) * bytes];

	  /*  Determine a run-length encoded version of the row  */
	  run_length_encode (sp, buf, width, bytes);

	  for (col = 0; col < width; col++)
	    {
	      start = (col < length) ? -col : -length;
	      end = (width <= (col + length)) ? (width - col - 1) : length;

	      val = 0;
	      i = start;
	      b = buf + (col + i) * 2;

	      if (start != -length)
		val += initial_p * (sum[start] - sum[-length]);

	      while (i < end)
		{
		  pixels = b[0];
		  i += pixels;
		  if (i > end)
		    i = end;
		  val += b[1] * (sum[i] - sum[start]);
		  b += (pixels * 2);
		  start = i;
		}

	      if (end != length)
		val += initial_m * (sum[length] - sum[end]);

	      val = val / total;

	      dp[col * bytes] = val;
	    }
      
	  pixel_region_set_row (srcR, srcR->x, row + srcR->y, width, dest);
	}

      g_free (sum - length);
      g_free (curve - length);
    }

  g_free (buf);
}


/* non-interpolating scale_region.  [adam]
 */
void
scale_region_no_resample (PixelRegion *srcPR,
			  PixelRegion *destPR)
{
  gint   *x_src_offsets;
  gint   *y_src_offsets;
  guchar *src;
  guchar *dest;
  gint    width, height, orig_width, orig_height;
  gint    last_src_y;
  gint    row_bytes;
  gint    x, y, b;
  gchar   bytes;

  orig_width = srcPR->w;
  orig_height = srcPR->h;

  width = destPR->w;
  height = destPR->h;

  bytes = srcPR->bytes;

  /*  the data pointers...  */
  x_src_offsets = (int *) g_malloc (width * bytes * sizeof(int));
  y_src_offsets = (int *) g_malloc (height * sizeof(int));
  src  = (guchar *) g_malloc (orig_width * bytes);
  dest = (guchar *) g_malloc (width * bytes);
  
  /*  pre-calc the scale tables  */
  for (b = 0; b < bytes; b++)
    {
      for (x = 0; x < width; x++)
	{
	  x_src_offsets [b + x * bytes] = b + bytes * ((x * orig_width + orig_width / 2) / width);
	}
    }
  for (y = 0; y < height; y++)
    {
      y_src_offsets [y] = (y * orig_height + orig_height / 2) / height;
    }
  
  /*  do the scaling  */
  row_bytes = width * bytes;
  last_src_y = -1;
  for (y = 0; y < height; y++)
    {
      /* if the source of this line was the same as the source
       *  of the last line, there's no point in re-rescaling.
       */
      if (y_src_offsets[y] != last_src_y)
	{
	  pixel_region_get_row (srcPR, 0, y_src_offsets[y], orig_width, src, 1);
	  for (x = 0; x < row_bytes ; x++)
	    {
	      dest[x] = src[x_src_offsets[x]];
	    }
	  last_src_y = y_src_offsets[y];
	}

      pixel_region_set_row (destPR, 0, y, width, dest);
    }
  
  g_free (x_src_offsets);
  g_free (y_src_offsets);
  g_free (src);
  g_free (dest);
}


static void
get_premultiplied_double_row (PixelRegion *srcPR,
			      gint         x,
			      gint         y,
			      gint         w,
			      gdouble     *row,
			      guchar      *tmp_src,
			      gint         n)
{
  gint b;
  gint bytes = srcPR->bytes;

  pixel_region_get_row (srcPR, x, y, w, tmp_src, n);

  if (pixel_region_has_alpha (srcPR))
    {
      /* premultiply the alpha into the double array */
      gdouble *irow  = row;
      gint     alpha = bytes - 1;
      gdouble  mod_alpha;

      for (x = 0; x < w; x++)
	{
	  mod_alpha = tmp_src[alpha] / 255.0;
	  for (b = 0; b < alpha; b++)
	    irow[b] = mod_alpha * tmp_src[b];
	  irow[b] = tmp_src[alpha];
	  irow += bytes;
	  tmp_src += bytes;
	}
    }
  else /* no alpha */
    {
      for (x = 0; x <  w*bytes; x++)
	row[x] = tmp_src[x];
    }

  /* set the off edge pixels to their nearest neighbor */
  for (b = 0; b < 2 * bytes; b++)
    row[-2*bytes + b] = row[(b%bytes)];
  for (b = 0; b < bytes * 2; b++)
    row[w*bytes + b] = row[(w - 1) * bytes + (b%bytes)];
}


static void
expand_line (gdouble           *dest,
	     gdouble           *src,
	     gint               bytes,
	     gint               old_width,
	     gint               width,
	     InterpolationType  interp)
{
  gdouble  ratio;
  gint     x,b;
  gint     src_col;
  gdouble  frac;
  gdouble *s;

  ratio = old_width / (gdouble) width;

/* this could be opimized much more by precalculating the coeficients for
   each x */
  switch(interp)
  {
    case CUBIC_INTERPOLATION:
      for (x = 0; x < width; x++)
      {
	src_col = ((int)((x) * ratio  + 2.0 - 0.5)) - 2;
	/* +2, -2 is there because (int) rounds towards 0 and we need 
	   to round down */
	frac =          ((x) * ratio - 0.5) - src_col;
	s = &src[src_col * bytes];
	for (b = 0; b < bytes; b++)
	  dest[b] = cubic (frac, s[b - bytes], s[b], s[b+bytes], s[b+bytes*2]);
	dest += bytes;
      }
      break;
    case LINEAR_INTERPOLATION:
      for (x = 0; x < width; x++)
      {
	src_col = ((int)((x) * ratio + 2.0 - 0.5)) - 2;
	/* +2, -2 is there because (int) rounds towards 0 and we need 
	   to round down */
	frac =          ((x) * ratio - 0.5) - src_col;
	s = &src[src_col * bytes];
	for (b = 0; b < bytes; b++)
	  dest[b] = ((s[b + bytes] - s[b]) * frac + s[b]);
	dest += bytes;
      }
      break;
   case NEAREST_NEIGHBOR_INTERPOLATION:
     g_error("sampling_type can't be "
	     "NEAREST_NEIGHBOR_INTERPOLATION");
  }
}


static void
shrink_line (gdouble           *dest,
	     gdouble           *src,
	     gint               bytes,
	     gint               old_width,
	     gint               width,
	     InterpolationType  interp)
{
  gint x, b;
  gdouble *source, *destp;
  register gdouble accum;
  register guint max;
  register gdouble mant, tmp;
  register const gdouble step = old_width / (gdouble) width;
  register const gdouble inv_step = 1.0 / step;
  gdouble position;

  fprintf(stderr, "shrink_line bytes=%d old_width=%d width=%d interp=%d "
	  "step=%f inv_step=%f\n",
          bytes, old_width, width, interp, step, inv_step);

  for (b = 0; b < bytes; b++)
  {
    
    source = &src[b];
    destp = &dest[b];
    position = -1;

    mant = *source;

    for (x = 0; x < width; x++)
    {
      source+= bytes;
      accum = 0;
      max = ((int)(position+step)) - ((int)(position));
      max--;
      while (max)
      {
	accum += *source;
	source += bytes;
	max--;
      }
      tmp = accum + mant;
      mant = ((position+step) - (int)(position + step));
      mant *= *source;
      tmp += mant;
      tmp *= inv_step;
      mant = *source - mant;
      *(destp) = tmp;
      destp += bytes;
      position += step;
	
    }
  }
}

static void
get_scaled_row (void        **src,
		gint          y,
		gint          new_width,
		PixelRegion  *srcPR,
		gdouble      *row,
		guchar       *src_tmp)
{
/* get the necesary lines from the source image, scale them,
   and put them into src[] */
  rotate_pointers(src, 4);
  if (y < 0)
    y = 0;
  if (y < srcPR->h)
  {
    get_premultiplied_double_row(srcPR, 0, y, srcPR->w,
				 row, src_tmp, 1);
    if (new_width > srcPR->w)
      expand_line(src[3], row, srcPR->bytes, 
		  srcPR->w, new_width, interpolation_type);
    else if (srcPR->w > new_width)
      shrink_line(src[3], row, srcPR->bytes, 
		  srcPR->w, new_width, interpolation_type);
    else /* no scailing needed */
      memcpy(src[3], row, sizeof (double) * new_width * srcPR->bytes);
  }
  else
    memcpy(src[3], src[2], sizeof (double) * new_width * srcPR->bytes);
}
void
scale_region (PixelRegion *srcPR,
	      PixelRegion *destPR)
{
  gdouble *src[4];
  guchar  *src_tmp;
  guchar  *dest;
  double  *row, *accum;
  gint     bytes, b;
  gint     width, height;
  gint     orig_width, orig_height;
  gdouble  y_rat;
  gint     i;
  gint     old_y = -4, new_y;
  gint     x, y;

  if (interpolation_type == NEAREST_NEIGHBOR_INTERPOLATION)
  {
    scale_region_no_resample (srcPR, destPR);
    return;
   }

  orig_width = srcPR->w;
  orig_height = srcPR->h;

  width = destPR->w;
  height = destPR->h;

  fprintf(stderr, "scale_region: (%d x %d) -> (%d x %d)\n",
	  orig_width, orig_height, width, height);

  /*  find the ratios of old y to new y  */
  y_rat = (double) orig_height / (double) height;

  bytes = destPR->bytes;

  /*  the data pointers...  */
  for (i = 0; i < 4; i++)
    src[i]    = g_new (double, (width) * bytes);
  dest   = g_new (guchar, width * bytes);

  src_tmp = g_new (guchar, orig_width * bytes);

 /* offset the row pointer by 2*bytes so the range of the array 
    is [-2*bytes] to [(orig_width + 2)*bytes] */
  row = g_new(double, (orig_width + 2*2) * bytes);
  row += bytes*2;

  accum = g_new(double, (width) * bytes);

  /*  Scale the selected region  */
  
  for (y = 0; y < height;  y++)
  {
    if (height < orig_height)
    {
      gint max;
      double frac;
      const double inv_ratio = 1.0 / y_rat;
      if (y == 0) /* load the first row if this it the first time through  */
	get_scaled_row((void **)&src[0], 0, width, srcPR, row,
		       src_tmp);
      new_y = (int)((y) * y_rat);
      frac = 1.0 - (y*y_rat - new_y);
      for (x  = 0; x < width*bytes; x++)
	accum[x] = src[3][x] * frac;

      max = ((int)((y+1) *y_rat)) - (new_y);
      max--;

      get_scaled_row((void **)&src[0], ++new_y, width, srcPR, row,
		     src_tmp);
      
      while (max > 0)
      {
	for (x  = 0; x < width*bytes; x++)
	  accum[x] += src[3][x];
	get_scaled_row((void **)&src[0], ++new_y, width, srcPR, row,
		       src_tmp);
	max--;
      }
      frac = (y + 1)*y_rat - ((int)((y + 1)*y_rat));
      for (x  = 0; x < width*bytes; x++)
      {
	accum[x] += frac * src[3][x];
	accum[x] *= inv_ratio;
      }
    }      
    else if (height > orig_height)
    {
      new_y = floor((y) * y_rat - .5);
    
      while (old_y <= new_y)
      { /* get the necesary lines from the source image, scale them,
	   and put them into src[] */
	get_scaled_row((void **)&src[0], old_y + 2, width, srcPR, row,
		       src_tmp);
	old_y++;
      }
      switch(interpolation_type)
      {
       case CUBIC_INTERPOLATION:
       {
	 double p0, p1, p2, p3;
	 double dy = ((y) * y_rat - .5) - new_y;
	 p0 = cubic(dy, 1, 0, 0, 0);
	 p1 = cubic(dy, 0, 1, 0, 0);
	 p2 = cubic(dy, 0, 0, 1, 0);
	 p3 = cubic(dy, 0, 0, 0, 1);
	 for (x = 0; x < width * bytes; x++)
	   accum[x] = p0 * src[0][x] + p1 * src[1][x] +
	     p2 * src[2][x] + p3 * src[3][x];
       } break;
       case LINEAR_INTERPOLATION:
       {
	 double idy = ((y) * y_rat - 0.5) - new_y;
	 double dy = 1.0 - idy;
	 for (x = 0; x < width * bytes; x++)
	   accum[x] = dy * src[1][x] + idy * src[2][x];
       } break;
       case NEAREST_NEIGHBOR_INTERPOLATION:
	 g_error("sampling_type can't be "
		 "NEAREST_NEIGHBOR_INTERPOLATION");

      }
    }
    else /* height == orig_height */
    {
      get_scaled_row((void **)&src[0], y, width, srcPR, row,
		     src_tmp);
      memcpy(accum, src[3], sizeof(double) * width * bytes);
    }
    if (pixel_region_has_alpha(srcPR))
    { /* unmultiply the alpha */
      double inv_alpha;
      double *p = accum;
      gint alpha = bytes - 1;
      gint result;
      guchar *d = dest;
      for (x = 0; x < width; x++)
      {
	if (p[alpha] > 0.001)
	{
	  inv_alpha = 255.0 / p[alpha];
	  for (b = 0; b < alpha; b++)
	  {
	    result = RINT(inv_alpha * p[b]);
	    if (result < 0)
	      d[b] = 0;
	    else if (result > 255)
	      d[b] = 255;
	    else
	      d[b] = result;
	  }
	  result = RINT(p[alpha]);
	  if (result > 255)
	    d[alpha] = 255;
	  else
	    d[alpha] = result;
	}
	else /* alpha <= 0 */
	  for (b = 0; b <= alpha; b++)
	    d[b] = 0;
	d += bytes;
	p += bytes;

      }
    }
    else
    {
      gint w = width * bytes;
      for (x = 0; x < w; x++)
      {
	if (accum[x] < 0.0)
	  dest[x] = 0;
	else if (accum[x] > 255.0)
	  dest[x] = 255;
	else
	  dest[x] = RINT(accum[x]);
      }
    }
    pixel_region_set_row (destPR, 0, y, width, dest);
  }

  /*  free up temporary arrays  */
  g_free (accum);
  for (i = 0; i < 4; i++)
    g_free (src[i]);
  g_free (src_tmp);
  g_free (dest);
  row -= 2*bytes;
  g_free (row);
}

void
subsample_region (PixelRegion *srcPR,
		  PixelRegion *destPR,
		  gint         subsample)
{
  guchar  * src, * s;
  guchar  * dest, * d;
  gdouble * row, * r;
  gint destwidth;
  gint src_row, src_col;
  gint bytes, b;
  gint width, height;
  gint orig_width, orig_height;
  gdouble x_rat, y_rat;
  gdouble x_cum, y_cum;
  gdouble x_last, y_last;
  gdouble * x_frac, y_frac, tot_frac;
  gint i, j;
  gint frac;
  gint advance_dest;

  orig_width = srcPR->w / subsample;
  orig_height = srcPR->h / subsample;
  width = destPR->w;
  height = destPR->h;

  fprintf(stderr, "subsample_region: (%d x %d) -> (%d x %d)\n",
	  orig_width, orig_height, width, height);

  /*  Some calculations...  */
  bytes = destPR->bytes;
  destwidth = destPR->rowstride;

  /*  the data pointers...  */
  src = (guchar *) g_malloc (orig_width * bytes);
  dest = destPR->data;

  /*  find the ratios of old x to new x and old y to new y  */
  x_rat = (double) orig_width / (double) width;
  y_rat = (double) orig_height / (double) height;

  /*  allocate an array to help with the calculations  */
  row    = (double *) g_malloc (sizeof (double) * width * bytes);
  x_frac = (double *) g_malloc (sizeof (double) * (width + orig_width));

  /*  initialize the pre-calculated pixel fraction array  */
  src_col = 0;
  x_cum = (double) src_col;
  x_last = x_cum;

  for (i = 0; i < width + orig_width; i++)
    {
      if (x_cum + x_rat <= (src_col + 1 + EPSILON))
	{
	  x_cum += x_rat;
	  x_frac[i] = x_cum - x_last;
	}
      else
	{
	  src_col ++;
	  x_frac[i] = src_col - x_last;
	}
      x_last += x_frac[i];
    }

  /*  clear the "row" array  */
  memset (row, 0, sizeof (double) * width * bytes);

  /*  counters...  */
  src_row = 0;
  y_cum = (double) src_row;
  y_last = y_cum;

  pixel_region_get_row (srcPR, 0, src_row * subsample, orig_width * subsample, src, subsample);

  /*  Scale the selected region  */
  for (i = 0; i < height; )
    {
      src_col = 0;
      x_cum = (double) src_col;

      /* determine the fraction of the src pixel we are using for y */
      if (y_cum + y_rat <= (src_row + 1 + EPSILON))
	{
	  y_cum += y_rat;
	  y_frac = y_cum - y_last;
	  advance_dest = TRUE;
	}
      else
	{
	  src_row ++;
	  y_frac = src_row - y_last;
	  advance_dest = FALSE;
	}

      y_last += y_frac;

      s = src;
      r = row;

      frac = 0;
      j = width;

      while (j)
	{
	  tot_frac = x_frac[frac++] * y_frac;

	  for (b = 0; b < bytes; b++)
	    r[b] += s[b] * tot_frac;

	  /*  increment the destination  */
	  if (x_cum + x_rat <= (src_col + 1 + EPSILON))
	    {
	      r += bytes;
	      x_cum += x_rat;
	      j--;
	    }

	  /* increment the source */
	  else
	    {
	      s += bytes;
	      src_col++;
	    }
	}

      if (advance_dest)
	{
	  tot_frac = 1.0 / (x_rat * y_rat);

	  /*  copy "row" to "dest"  */
	  d = dest;
	  r = row;

	  j = width;
	  while (j--)
	    {
	      b = bytes;
	      while (b--)
		*d++ = (guchar) (*r++ * tot_frac + 0.5);
	    }

	  dest += destwidth;

	  /*  clear the "row" array  */
	  memset (row, 0, sizeof (double) * destwidth);

	  i++;
	}
      else
	pixel_region_get_row (srcPR, 0, src_row * subsample, orig_width * subsample, src, subsample);
    }

  /*  free up temporary arrays  */
  g_free (row);
  g_free (x_frac);
  g_free (src);
}


gfloat
shapeburst_region (PixelRegion *srcPR,
		   PixelRegion *distPR)
{
  Tile *tile;
  guchar *tile_data;
  gfloat max_iterations;
  gfloat *distp_cur;
  gfloat *distp_prev;
  gfloat *tmp;
  gfloat min_prev;
  gfloat float_tmp;
  gint min;
  gint min_left;
  gint length;
  gint i, j, k;
  gint src;
  gint fraction;
  gint prev_frac;
  gint x, y;
  gint end;
  gint boundary;
  gint inc;

  src = 0;

  max_iterations = 0.0;

  length = distPR->w + 1;
  distp_prev = (float *) paint_funcs_get_buffer (sizeof (float) * length * 2);
  for (i = 0; i < length; i++)
    distp_prev[i] = 0.0;

  distp_prev += 1;
  distp_cur = distp_prev + length;

  for (i = 0; i < srcPR->h; i++)
    {
      /*  set the current dist row to 0's  */
      memset(distp_cur - 1, 0, sizeof(float) * (length - 1));

      for (j = 0; j < srcPR->w; j++)
	{
	  min_prev = MIN (distp_cur[j-1], distp_prev[j]);
	  min_left = MIN ((srcPR->w - j - 1), (srcPR->h - i - 1));
	  min = (int) MIN (min_left, min_prev);
	  fraction = 255;

	  /*  This might need to be changed to 0 instead of k = (min) ? (min - 1) : 0  */
	  for (k = (min) ? (min - 1) : 0; k <= min; k++)
	    {
	      x = j;
	      y = i + k;
	      end = y - k;

	      while (y >= end)
		{
		  tile = tile_manager_get_tile (srcPR->tiles, 
						x, y, TRUE, FALSE);
		  tile_data = tile_data_pointer (tile, 
						 x % TILE_WIDTH, 
						 y % TILE_HEIGHT);
		  boundary = MIN ((y % TILE_HEIGHT),
				  (tile_ewidth (tile) - (x % TILE_WIDTH) - 1));
		  boundary = MIN (boundary, (y - end)) + 1;
		  inc = 1 - tile_ewidth (tile);

		  while (boundary--)
		    {
		      src = *tile_data;
		      if (src == 0)
			{
			  min = k;
			  y = -1;
			  break;
			}
		      if (src < fraction)
			fraction = src;

		      x++;
		      y--;
		      tile_data += inc;
		    }

		  tile_release (tile, FALSE);
		}
	    }

	  if (src != 0)
	    {
	      /*  If min_left != min_prev use the previous fraction
	       *   if it is less than the one found
	       */
	      if (min_left != min)
		{
		  prev_frac = (int) (255 * (min_prev - min));
		  if (prev_frac == 255)
		    prev_frac = 0;
		  fraction = MIN (fraction, prev_frac);
		}
	      min++;
	    }

	  float_tmp = distp_cur[j] = min + fraction / 256.0;

	  if (float_tmp > max_iterations)
	    max_iterations = float_tmp;
	}

      /*  set the dist row  */
      pixel_region_set_row (distPR, distPR->x, distPR->y + i, distPR->w, (guchar *) distp_cur);

      /*  swap pointers around  */
      tmp = distp_prev;
      distp_prev = distp_cur;
      distp_cur = tmp;
    }

  return max_iterations;
}

static void
rotate_pointers (gpointer *p, 
		 guint32   n)
{
  guint32  i;
  gpointer tmp;

  tmp = p[0];
  for (i = 0; i < n-1; i++)
    {
      p[i] = p[i+1];
    }
  p[i] = tmp;
}

static void
compute_border (gint16  *circ, 
		guint16  xradius, 
		guint16  yradius)
{
  gint32 i;
  gint32 diameter = xradius*2 +1;
  gdouble tmp;

  for (i = 0; i < diameter; i++)
  {
    if (i > xradius)
      tmp = (i - xradius) - .5;
    else if (i < xradius)
      tmp = (xradius - i) - .5;
    else
      tmp = 0.0;

    circ[i] = RINT (yradius / (gdouble) xradius *
		    sqrt ((xradius) * (xradius) - (tmp) * (tmp)));
  }
}

void
fatten_region (PixelRegion *src,
	       gint16       xradius,
	       gint16       yradius)
{
/*
  Any bugs in this fuction are probably also in thin_region  
  Blame all bugs in this function on jaycox@gimp.org
*/
  register gint32 i, j, x, y;

  guchar  **buf; /* caches the region's pixel data */
  guchar   *out;  /* holds the new scan line we are computing */
  guchar  **max; /* caches the largest values for each column */
  gint16   *circ; /* holds the y coords of the filter's mask */
  gint16    last_max, last_index;

  guchar   *buffer;

  if (xradius <= 0 || yradius <= 0)
    return;

  max = (guchar **)g_malloc ((src->w + 2*xradius) * sizeof(void *));
  buf = (guchar **)g_malloc((yradius + 1) * sizeof(void *));
  for (i = 0; i < yradius+1; i++)
  {
    buf[i] = (guchar *)g_malloc(src->w * sizeof(guchar));
  }
  buffer = g_malloc((src->w + 2*xradius)*(yradius + 1) * sizeof(guchar));
  for (i = 0; i < src->w + 2*xradius; i++)
  {
    if (i < xradius)
      max[i] = buffer;
    else if (i < src->w + xradius)
      max[i] = &buffer[(yradius+1)*(i - xradius)];
    else
      max[i] = &buffer[(yradius+1)*(src->w + xradius - 1)];

    for (j = 0 ; j < xradius + 1; j++)
      max[i][j] = 0;
  }
 /* offset the max pointer by xradius so the range of the array 
    is [-xradius] to [src->w + xradius] */
  max += xradius;

  out =  (guchar *)g_malloc (src->w * sizeof(guchar));

  circ = (short *)g_malloc ((2*xradius + 1) * sizeof(gint16));
  compute_border (circ, xradius, yradius);

 /* offset the circ pointer by xradius so the range of the array 
    is [-xradius] to [xradius] */
  circ += xradius;

  memset (buf[0], 0, src->w);
  for (i = 0; i < yradius && i < src->h; i++) /* load top of image */
    pixel_region_get_row (src, src->x, src->y + i, src->w, buf[i+1], 1);

  for (x = 0; x < src->w; x++) /* set up max for top of image */
  {
    max[x][0] = buf[0][x];
    for (j = 1; j < yradius+1; j++)
      if (max[x][j] < buf[j][x])
	max[x][j] = buf[j][x];
      else
	max[x][j] = max[x][j-1];
  }
  for (y = 0; y < src->h; y++)
  {
    rotate_pointers((void **)buf, yradius+1);
    if (y < src->h - (yradius))
      pixel_region_get_row (src, src->x, src->y + y + yradius, src->w,
			    buf[yradius], 1);
    else
      memset (buf[yradius], 0, src->w);
    for (x = 0 ; x < src->w; x++) /* update max array */
    {
      for (i = yradius; i > 0; i--)
      {
	max[x][i] = (MAX (MAX (max[x][i - 1], buf[i-1][x]), buf[i][x]));
      }
      max[x][0] = buf[0][x];
    }
    last_max =  max[0][circ[-1]];
    last_index = 1;
    for (x = 0 ; x < src->w; x++) /* render scan line */
    {
      last_index--;
      if (last_index >= 0)
      {
	if (last_max == 255)
	  out[x] = 255;
	else
	{
	  last_max = 0;
	  for (i = xradius; i >= 0; i--)
	    if (last_max < max[x+i][circ[i]])
	    {
	      last_max = max[x+i][circ[i]];
	      last_index = i;
	    }
	  out[x] = last_max;
	}
      }
      else
      {
	last_index = xradius;
	last_max = max[x+xradius][circ[xradius]];
	for (i = xradius-1; i >= -xradius; i--)
	  if (last_max < max[x+i][circ[i]])
	  {
	    last_max = max[x+i][circ[i]];
	    last_index = i;
	  }
	out[x] = last_max;
      }
    }
    pixel_region_set_row (src, src->x, src->y + y, src->w, out);
  }
  /* undo the offsets to the pointers so we can free the malloced memmory */
  circ -= xradius;
  max -= xradius;

  g_free (circ);
  g_free (buffer);
  g_free (max);
  for (i = 0; i < yradius + 1; i++)
    g_free (buf[i]);
  g_free (buf);
  g_free (out);
}

void
thin_region (PixelRegion *src,
	     gint16       xradius,
	     gint16       yradius,
	     gint         edge_lock)
{
/*
  pretty much the same as fatten_region only different
  blame all bugs in this function on jaycox@gimp.org
*/
  /* If edge_lock is true  we assume that pixels outside the region
     we are passed are identical to the edge pixels.
     If edge_lock is false, we assume that pixels outside the region are 0
  */
  register gint32 i, j, x, y;
  guchar  **buf; /* caches the the region's pixels */
  guchar   *out;  /* holds the new scan line we are computing */
  guchar  **max; /* caches the smallest values for each column */
  gint16   *circ; /* holds the y coords of the filter's mask */
  gint16    last_max, last_index;

  guchar   *buffer;

  if (xradius <= 0 || yradius <= 0)
    return;

  max = (guchar **)g_malloc ((src->w+2*xradius) * sizeof(void *));
  buf = (guchar **)g_malloc ((yradius+1) * sizeof(void *));
  for (i = 0; i < yradius+1; i++)
  {
    buf[i] = (guchar *)g_malloc (src->w * sizeof(guchar));
  }
  buffer = g_malloc ((src->w+2*xradius + 1)*(yradius+1));
  if (edge_lock)
    memset(buffer, 255, (src->w+2*xradius + 1)*(yradius+1));
  else
    memset(buffer, 0, (src->w+2*xradius + 1)*(yradius+1));
  for (i = 0; i < src->w+2*xradius; i++)
  {
    if (i < xradius)
      if (edge_lock)
	max[i] = buffer;
      else
	max[i] = &buffer[(yradius+1)*(src->w + xradius)];
    else if (i < src->w + xradius)
      max[i] = &buffer[(yradius+1)*(i - xradius)];
    else
      if (edge_lock)
	max[i] = &buffer[(yradius+1)*(src->w + xradius - 1)];
      else
	max[i] = &buffer[(yradius+1)*(src->w + xradius)];
  }
  if (!edge_lock)
    for (j = 0 ; j < xradius+1; j++)
      max[0][j] = 0;

 /* offset the max pointer by xradius so the range of the array 
    is [-xradius] to [src->w + xradius] */
  max += xradius;

  out = (guchar *)g_malloc(src->w);

  circ = (short *)g_malloc((2*xradius + 1)*sizeof(gint16));
  compute_border(circ, xradius, yradius);

 /* offset the circ pointer by xradius so the range of the array 
    is [-xradius] to [xradius] */
  circ += xradius;

  for (i = 0; i < yradius && i < src->h; i++) /* load top of image */
    pixel_region_get_row (src, src->x, src->y + i, src->w, buf[i+1], 1);
  if (edge_lock)
    memcpy (buf[0], buf[1], src->w);
  else
    memset (buf[0], 0, src->w);
  for (x = 0; x < src->w; x++) /* set up max for top of image */
  {
    max[x][0] = buf[0][x];
    for (j = 1; j < yradius+1; j++)
      if (max[x][j] > buf[j][x])
	max[x][j] = buf[j][x];
      else
	max[x][j] = max[x][j-1];
  }
  for (y = 0; y < src->h; y++)
  {
    rotate_pointers ((void **)buf, yradius+1);
    if (y < src->h - (yradius))
      pixel_region_get_row (src, src->x, src->y + y + yradius, src->w,
			    buf[yradius], 1);
    else if (edge_lock)
      memcpy (buf[yradius], buf[yradius -1], src->w);
    else
      memset (buf[yradius], 0, src->w);
    for (x = 0 ; x < src->w; x++) /* update max array */
    {
      for (i = yradius; i > 0; i--)
      {
	max[x][i] = (MIN (MIN (max[x][i - 1], buf[i-1][x]), buf[i][x]));
      }
      max[x][0] = buf[0][x];
    }
    last_max =  max[0][circ[-1]];
    last_index = 0;
    for (x = 0 ; x < src->w; x++) /* render scan line */
    {
      last_index--;
      if (last_index >= 0)
      {
	if (last_max == 0)
	  out[x] = 0;
	else
	{
	  last_max = 255;
	  for (i = xradius; i >= 0; i--)
	    if (last_max > max[x+i][circ[i]])
	    {
	      last_max = max[x+i][circ[i]];
	      last_index = i;
	    }
	  out[x] = last_max;
	}
      }
      else
      {
	last_index = xradius;
	last_max = max[x+xradius][circ[xradius]];
	for (i = xradius-1; i >= -xradius; i--)
	  if (last_max > max[x+i][circ[i]])
	  {
	    last_max = max[x+i][circ[i]];
	    last_index = i;
	  }
	out[x] = last_max;
      }
    }
    pixel_region_set_row (src, src->x, src->y + y, src->w, out);
  }
  /* undo the offsets to the pointers so we can free the malloced memmory */
  circ -= xradius;
  max -= xradius;
  /* free the memmory */
  g_free (circ);
  g_free (buffer);
  g_free (max);
  for (i = 0; i < yradius + 1; i++)
    g_free (buf[i]);
  g_free (buf);
  g_free (out);
}

static void
compute_transition (guchar  *transition,
		    guchar **buf,
		    gint32   width)
{
  register gint32 x = 0;

  if (width == 1)
  {
    if (buf[1][x] > 127 && (buf[0][x] < 128 || buf[2][x] < 128))
      transition[x] = 255;
    else
      transition[x] = 0;
    return;
  }
  if (buf[1][x] > 127)
  {
    if ( buf[0][x] < 128 || buf[0][x+1] < 128 ||
	                    buf[1][x+1] < 128 ||
	 buf[2][x] < 128 || buf[2][x+1] < 128 )
      transition[x] = 255;
    else
      transition[x] = 0;
  }
  else
    transition[x] = 0;
  for (x = 1; x < width - 1; x++)
  {
    if (buf[1][x] >= 128)
    {
      if (buf[0][x-1] < 128 || buf[0][x] < 128 || buf[0][x+1] < 128 ||
	  buf[1][x-1] < 128           ||          buf[1][x+1] < 128 ||
	  buf[2][x-1] < 128 || buf[2][x] < 128 || buf[2][x+1] < 128)
	transition[x] = 255;
      else
	transition[x] = 0;
    }
    else
      transition[x] = 0;
  }
  if (buf[1][x] >= 128)
  {
    if ( buf[0][x-1] < 128 || buf[0][x] < 128 ||
	 buf[1][x-1] < 128 ||
	 buf[2][x-1] < 128 || buf[2][x] < 128)
      transition[x] = 255;
    else
      transition[x] = 0;
  }
  else
    transition[x] = 0;
}

void
border_region (PixelRegion *src,
	       gint16       xradius,
	       gint16       yradius)
{
/*
  This function has no bugs, but if you imagine some you can
  blame them on jaycox@gimp.org
*/
  register gint32 i, j, x, y;
  guchar **buf, *out;
  gint16 *max;
  guchar **density;
  guchar **transition;
  guchar last_max;
  gint16 last_index;

  if (xradius < 0 || yradius < 0)
  {
    g_warning ("border_region: negative radius specified.");
    return;
  }
  if (xradius == 0 || yradius == 0)
  {
    guchar color[] = "\0\0\0\0";
    color_region(src, color);
    return;
  }
  if (xradius == 1 && yradius == 1) /* optimize this case specifically */
  {
    guchar *transition;
    guchar *source[3];
    for (i = 0; i < 3; i++)
      source[i] = (guchar *)g_malloc ((src->w)*sizeof(guchar));

    transition = (guchar *)g_malloc ((src->w)*sizeof(guchar));

    pixel_region_get_row (src, src->x, src->y + 0, src->w, source[0], 1);
    memcpy (source[1], source[0], src->w);
    if (src->h > 1)
      pixel_region_get_row (src, src->x, src->y + 1, src->w, source[2], 1);
    else
      memcpy (source[2], source[1], src->w);

    compute_transition (transition, source, src->w);
    pixel_region_set_row (src, src->x, src->y , src->w, transition);
    
    for (y = 1; y < src->h; y++)
    {
      rotate_pointers ((void **)source, 3);
      if (y +1 < src->h)
	pixel_region_get_row (src, src->x, src->y +y +1, src->w, source[2], 1);
      else
	memcpy(source[2], source[1], src->w);
      compute_transition (transition, source, src->w);
      pixel_region_set_row (src, src->x, src->y + y, src->w, transition);
      
    }
    for (i = 0; i < 3; i++)
      g_free(source[i]);
    g_free(transition);
    return;
  } /* end of if (xradius == 1 && yradius == 1) */
  max = (gint16 *)g_malloc ((src->w+2*xradius)*sizeof(gint16 *));
  for (i = 0; i < (src->w+2*xradius); i++)
    max[i] = yradius+2;
  max += xradius;

  buf = (guchar **)g_malloc ((3)*sizeof(void *));
  for (i = 0; i < 3; i++)
  {
    buf[i] = (guchar *)g_malloc ((src->w)*sizeof(guchar));
  }
  transition = (guchar **)g_malloc ((yradius+1)*sizeof(void*));
  for (i = 0; i < yradius +1; i++)
  {
    transition[i] = (guchar *)g_malloc (src->w+2*xradius);
    memset(transition[i], 0, src->w+2*xradius);
    transition[i] += xradius;
  }
  out = (guchar *)g_malloc ((src->w)*sizeof(guchar));
  density = (guchar **)g_malloc ((2*xradius + 1)*sizeof(void *));
  density += xradius;

  for (x = 0; x < (xradius+1); x++) /* allocate density[][] */
  {
    density[ x]  = (guchar *)g_malloc (2*yradius +1);
    density[ x] += yradius;
    density[-x]  = density[x];
  }
  for (x = 0; x < (xradius+1); x++) /* compute density[][] */
  {
    register double tmpx, tmpy, dist;
    guchar a;
    if (x > 0)
      tmpx = x - 0.5;
    else if (x < 0)
      tmpx = x + 0.5;
    else
      tmpx = 0.0;
    for (y = 0; y < (yradius+1); y++)
    {
      if (y > 0)
	tmpy = y - 0.5;
      else if (y < 0)
	tmpy = y + 0.5;
      else
	tmpy = 0.0;
      dist = (tmpy*tmpy)/(yradius*yradius) + (tmpx*tmpx)/(xradius*xradius);
      if (dist < 1.0)
	a = 255*(1.0 - sqrt (dist));
      else
	a = 0;
      density[ x][ y] = a;
      density[ x][-y] = a;
      density[-x][ y] = a;
      density[-x][-y] = a;
    }
  }
  pixel_region_get_row (src, src->x, src->y + 0, src->w, buf[0], 1);
  memcpy (buf[1], buf[0], src->w);
  if (src->h > 1)
    pixel_region_get_row (src, src->x, src->y + 1, src->w, buf[2], 1);
  else
    memcpy (buf[2], buf[1], src->w);
  compute_transition (transition[1], buf, src->w);

  for (y = 1; y < yradius && y + 1< src->h; y++) /* set up top of image */
  {
    rotate_pointers ((void **)buf, 3);
    pixel_region_get_row (src, src->x, src->y + y + 1, src->w, buf[2], 1);
    compute_transition (transition[y + 1], buf, src->w);
  }
  for (x = 0; x < src->w; x++) /* set up max[] for top of image */
  {
    max[x] = -(yradius+7); 
    for (j = 1; j < yradius+1; j++)
      if (transition[j][x])
      {
	max[x] = j;
	break;
      }
  }
  for (y = 0; y < src->h; y++) /* main calculation loop */
  {
    rotate_pointers ((void **)buf, 3);
    rotate_pointers ((void **)transition, yradius + 1);
    if (y < src->h - (yradius+1))
    {
      pixel_region_get_row (src, src->x, src->y + y + yradius + 1, src->w,
			    buf[2], 1);
      compute_transition (transition[yradius], buf, src->w);
    }
    else
      memcpy (transition[yradius], transition[yradius - 1], src->w);

    for (x = 0; x < src->w; x++) /* update max array */
    {
      if (max[x] < 1)
      {
	if (max[x] <= -yradius)
	{
	  if (transition[yradius][x])
	    max[x] = yradius;
	  else
	    max[x]--;
	}
	else
	  if (transition[-max[x]][x])
	    max[x] = -max[x];
	  else if (transition[-max[x]+1][x])
	    max[x] = -max[x]+1;
	  else
	    max[x]--;
      }
      else
	max[x]--;
      if (max[x] < -yradius - 1)
	max[x] = -yradius -1;
    }
    last_max =  max[0][density[-1]];
    last_index = 1;
    for (x = 0 ; x < src->w; x++) /* render scan line */
    {
      last_index--;
      if (last_index >= 0)
      {
	last_max = 0;
	for (i = xradius; i >= 0; i--)
	  if (max[x+i] <= yradius && max[x+i] >= -yradius &&
	      density[i][max[x+i]] > last_max)
	  {
	    last_max = density[i][max[x+i]];
	    last_index = i;
	  }
	out[x] = last_max;
      }
      else
      {
	last_max = 0;
	for (i = xradius; i >= -xradius; i--)
	  if (max[x+i] <= yradius && max[x+i] >= -yradius &&
	      density[i][max[x+i]] > last_max)
	  {
	    last_max = density[i][max[x+i]];
	    last_index = i;
	  }
	out[x] = last_max;
      }
      if (last_max == 0)
      {
	for (i = x+1; i < src->w; i++)
	{
	  if (max[i] >= -yradius)
	    break;
	}
	if (i - x > xradius)
	{
	  for (; x < i - xradius; x++)
	    out[x] = 0;
	  x--;
	}
	last_index = xradius;
      }
    }
    pixel_region_set_row (src, src->x, src->y + y, src->w, out);
  }
  g_free(out);

  for (i = 0; i < 3; i++)
    g_free(buf[i]);

  g_free (buf);
  max -= xradius;
  g_free (max);

  for (i = 0; i < yradius +1; i++)
    {
      transition[i] -= xradius;
      g_free (transition[i]);
    }
  g_free (transition);

  for (i = 0; i < xradius +1 ; i++)
    {
      density[i]-= yradius;
      g_free(density[i]);
    }
  density -= xradius;
  g_free(density);
}

void
swap_region (PixelRegion *src,
	     PixelRegion *dest)
{
  gint h;
  gint length;
  guchar * s, * d;
  void * pr;

  for (pr = pixel_regions_register (2, src, dest);
       pr != NULL;
       pr = pixel_regions_process (pr))
    {
      s = src->data;
      h = src->h;
      d = dest->data;
      length = src->w * src->bytes;

      while (h --)
	{
	  swap_pixels (s, d, length);
	  s += src->rowstride;
	  d += dest->rowstride;
	}
    }
}


static void
apply_mask_to_sub_region (gint        *opacityp,
			  PixelRegion *src,
			  PixelRegion *mask)
{
  gint    h;
  guchar *s;
  guchar *m;
  gint    opacity = *opacityp;
  
  s = src->data;
  m = mask->data;
  h = src->h;

  while (h --)
    {
      apply_mask_to_alpha_channel (s, m, opacity, src->w, src->bytes);
      s += src->rowstride;
      m += mask->rowstride;
    }
}

void
apply_mask_to_region (PixelRegion *src,
		      PixelRegion *mask,
		      gint         opacity)
{
  pixel_regions_process_parallel ((p_func)apply_mask_to_sub_region,
				  &opacity, 2, src, mask);
}


static void
combine_mask_and_sub_region (gint        *opacityp,
			     PixelRegion *src,
			     PixelRegion *mask)
{
  gint    h;
  guchar *s;
  guchar *m;
  gint    opacity = *opacityp;
  
  s = src->data;
  m = mask->data;
  h = src->h;

  while (h --)
  {
    combine_mask_and_alpha_channel (s, m, opacity, src->w, src->bytes);
    s += src->rowstride;
    m += mask->rowstride;
  }
}

void
combine_mask_and_region (PixelRegion *src,
			 PixelRegion *mask,
			 gint         opacity)
{

  pixel_regions_process_parallel ((p_func)combine_mask_and_sub_region,
				  &opacity, 2, src, mask);
}


void
copy_gray_to_region (PixelRegion *src,
		     PixelRegion *dest)
{
  gint    h;
  guchar *s;
  guchar *d;
  void   *pr;

  for (pr = pixel_regions_register (2, src, dest);
       pr != NULL;
       pr = pixel_regions_process (pr))
    {
      s = src->data;
      d = dest->data;
      h = src->h;

      while (h --)
	{
	  copy_gray_to_inten_a_pixels (s, d, src->w, dest->bytes);
	  s += src->rowstride;
	  d += dest->rowstride;
	}
    }
}


struct initial_regions_struct
{
  gint              opacity;
  LayerModeEffects  mode;
  gboolean         *affect;
  gint              type;
  guchar           *data;
};

void
initial_sub_region (struct initial_regions_struct *st, 
		    PixelRegion                   *src,
		    PixelRegion                   *dest,
		    PixelRegion                   *mask)
{
  gint              h;
  guchar           *s, *d, *m;
  guchar            buf[512];
  guchar           *data;
  gint              opacity;
  LayerModeEffects  mode;
  gboolean         *affect;
  gint              type;

  data    = st->data;
  opacity = st->opacity;
  mode    = st->mode;
  affect  = st->affect;
  type    = st->type;

  if (src->w * (src->bytes + 1) > 512)
    g_printerr ("initial_sub_region:: error :: src->w * (src->bytes + 1) > 512\n");

  s = src->data;
  d = dest->data;
  m = (mask) ? mask->data : NULL;

  for (h = 0; h < src->h; h++)
  {
    /*  based on the type of the initial image...  */
    switch (type)
    {
     case INITIAL_CHANNEL_MASK:
     case INITIAL_CHANNEL_SELECTION:
       initial_channel_pixels (s, d, src->w, dest->bytes);
       break;

     case INITIAL_INDEXED:
       initial_indexed_pixels (s, d, data, src->w);
       break;

     case INITIAL_INDEXED_ALPHA:
       initial_indexed_a_pixels (s, d, m, data, opacity, src->w);
       break;

     case INITIAL_INTENSITY:
       if (mode == DISSOLVE_MODE)
       {
	 dissolve_pixels (s, buf, src->x, src->y + h, opacity, src->w, src->bytes,
			  src->bytes + 1, 0);
	 initial_inten_pixels (buf, d, m, opacity, affect,
			       src->w, src->bytes);
       }
       else
	 initial_inten_pixels (s, d, m, opacity, affect, src->w, src->bytes);
       break;

     case INITIAL_INTENSITY_ALPHA:
       if (mode == DISSOLVE_MODE)
       {
	 dissolve_pixels (s, buf, src->x, src->y + h, opacity, src->w, src->bytes,
			  src->bytes, 1);
	 initial_inten_a_pixels (buf, d, m, opacity, affect,
				 src->w, src->bytes);
       }
       else
	 initial_inten_a_pixels (s, d, m, opacity, affect, src->w, src->bytes);
       break;
    }

    s += src->rowstride;
    d += dest->rowstride;
    if (mask)
      m += mask->rowstride;
  }
}

void
initial_region (PixelRegion	 *src,
		PixelRegion	 *dest,
		PixelRegion	 *mask,
		guchar	         *data,
		gint		  opacity,
		LayerModeEffects  mode,
		gboolean	 *affect,
		gint		  type)
{
  struct initial_regions_struct st;

  st.opacity = opacity;
  st.mode    = mode;
  st.affect  = affect;
  st.type    = type;
  st.data    = data;
  
  pixel_regions_process_parallel ((p_func)initial_sub_region, &st, 3,
				    src, dest, mask);
}

struct combine_regions_struct
{
  gint              opacity;
  LayerModeEffects  mode;
  gboolean         *affect;
  gint              type;
  guchar           *data;
  gboolean          has_alpha1, has_alpha2;
  gboolean          opacity_quickskip_possible;
  gboolean          transparency_quickskip_possible;
};



void
combine_sub_region (struct combine_regions_struct *st,
		    PixelRegion                   *src1,
		    PixelRegion                   *src2,
		    PixelRegion                   *dest,
		    PixelRegion                   *mask)
{
  guchar           *data;
  gint              opacity;
  LayerModeEffects  mode;
  gboolean         *affect;
  gint              type;
  gint              h;
  gboolean          has_alpha1, has_alpha2;
  gint              combine = 0;
  gint              mode_affect;
  guchar           *s, *s1, *s2;
  guchar           *d, *m;
  guchar            buf[512];
  gboolean          opacity_quickskip_possible;
  gboolean          transparency_quickskip_possible;
  TileRowHint       hint;

  opacity    = st->opacity;
  mode       = st->mode;
  affect     = st->affect;
  type       = st->type;
  data       = st->data;
  has_alpha1 = st->has_alpha1;
  has_alpha2 = st->has_alpha2;

  opacity_quickskip_possible = (st->opacity_quickskip_possible &&
				src2->tiles);
  transparency_quickskip_possible = (st->transparency_quickskip_possible &&
				     src2->tiles);

  s1 = src1->data;
  s2 = src2->data;
  d = dest->data;
  m = (mask) ? mask->data : NULL;

  if (src1->w > 128)
    g_error("combine_sub_region::src1->w = %d\n", src1->w);

  if (transparency_quickskip_possible || opacity_quickskip_possible)
    {
#ifdef HINTS_SANITY
      if (src1->h != src2->h)
	g_error("HEIGHTS SUCK!!");
      if (src1->offy != dest->offy)
	g_error("SRC1 OFFSET != DEST OFFSET");
#endif
      update_tile_rowhints (src2->curtile,
			    src2->offy, src2->offy + (src1->h - 1));
    }
  /* else it's probably a brush-composite */

  for (h = 0; h < src1->h; h++)
    {
      hint = TILEROWHINT_UNDEFINED;

      if (transparency_quickskip_possible)
	{
	  hint = tile_get_rowhint (src2->curtile, (src2->offy + h));

	  if (hint == TILEROWHINT_TRANSPARENT)
	    {
	      goto next_row;
	    }
	}
      else
	{
	  if (opacity_quickskip_possible)
	    {
	      hint = tile_get_rowhint (src2->curtile, (src2->offy + h));
	    }
	}
      
      s = buf;

      /*  apply the paint mode based on the combination type & mode  */
      switch (type)
	{
	case COMBINE_INTEN_A_INDEXED_A:
	case COMBINE_INTEN_A_CHANNEL_MASK:
	case COMBINE_INTEN_A_CHANNEL_SELECTION:
	  combine = type;
	  break;

	case COMBINE_INDEXED_INDEXED:
	case COMBINE_INDEXED_INDEXED_A:
	case COMBINE_INDEXED_A_INDEXED_A:
	  /*  Now, apply the paint mode--for indexed images  */
	  combine = apply_indexed_layer_mode (s1, s2, &s, mode,
					      has_alpha1, has_alpha2);
	  break;

	case COMBINE_INTEN_INTEN_A:
	case COMBINE_INTEN_A_INTEN:
	case COMBINE_INTEN_INTEN:
	case COMBINE_INTEN_A_INTEN_A:
	  /*  Now, apply the paint mode  */
	  combine = apply_layer_mode (s1, s2, &s, src1->x, src1->y + h,
				      opacity, src1->w, mode,
				      src1->bytes, src2->bytes,
				      has_alpha1, has_alpha2, &mode_affect);
	  break;

	default:
	  g_warning ("combine_sub_region: unhandled combine-type.");
	  break;
	}

      /*  based on the type of the initial image...  */
      switch (combine)
	{
	case COMBINE_INDEXED_INDEXED:
	  combine_indexed_and_indexed_pixels (s1, s2, d, m, opacity,
					      affect, src1->w,
					      src1->bytes);
	  break;
	    
	case COMBINE_INDEXED_INDEXED_A:
	  combine_indexed_and_indexed_a_pixels (s1, s2, d, m, opacity,
						affect, src1->w,
						src1->bytes);
	  break;
	    
	case COMBINE_INDEXED_A_INDEXED_A:
	  combine_indexed_a_and_indexed_a_pixels (s1, s2, d, m, opacity,
						  affect, src1->w,
						  src1->bytes);
	  break;
	    
	case COMBINE_INTEN_A_INDEXED_A:
	  /*  assume the data passed to this procedure is the
	   *  indexed layer's colormap
	   */
	  combine_inten_a_and_indexed_a_pixels (s1, s2, d, m, data, opacity,
						src1->w, dest->bytes);
	  break;
	    
	case COMBINE_INTEN_A_CHANNEL_MASK:
	  /*  assume the data passed to this procedure is the
	   *  indexed layer's colormap
	   */
	  combine_inten_a_and_channel_mask_pixels (s1, s2, d, data, opacity,
						   src1->w, dest->bytes);
	  break;
	    
	case COMBINE_INTEN_A_CHANNEL_SELECTION:
	  combine_inten_a_and_channel_selection_pixels (s1, s2, d, data,
							opacity,
							src1->w,
							src1->bytes);
	  break;
	    
	case COMBINE_INTEN_INTEN:
	  if ((hint == TILEROWHINT_OPAQUE) &&
	      opacity_quickskip_possible)
	    {
	      memcpy (d, s, dest->w * dest->bytes);
	    }
	  else
	    combine_inten_and_inten_pixels (s1, s, d, m, opacity,
					    affect, src1->w, src1->bytes);
	  break;
	    
	case COMBINE_INTEN_INTEN_A:
	  combine_inten_and_inten_a_pixels (s1, s, d, m, opacity,
					    affect, src1->w, src1->bytes);
	  break;
	    
	case COMBINE_INTEN_A_INTEN:
	  combine_inten_a_and_inten_pixels (s1, s, d, m, opacity,
					    affect, mode_affect, src1->w,
					    src1->bytes);
	  break;
	    
	case COMBINE_INTEN_A_INTEN_A:
	  if ((hint == TILEROWHINT_OPAQUE) &&
	      opacity_quickskip_possible)
	    {
	      memcpy (d, s, dest->w * dest->bytes);
	    }
	  else
	    combine_inten_a_and_inten_a_pixels (s1, s, d, m, opacity,
						affect, mode_affect,
						src1->w, src1->bytes);
	  break;
	    
	case BEHIND_INTEN:
	  behind_inten_pixels (s1, s, d, m, opacity,
			       affect, src1->w, src1->bytes,
			       src2->bytes, has_alpha1, has_alpha2);
	  break;
	    
	case BEHIND_INDEXED:
	  behind_indexed_pixels (s1, s, d, m, opacity,
				 affect, src1->w, src1->bytes,
				 src2->bytes, has_alpha1, has_alpha2);
	  break;
	    
	case REPLACE_INTEN:
	  replace_inten_pixels (s1, s, d, m, opacity,
				affect, src1->w, src1->bytes,
				src2->bytes, has_alpha1, has_alpha2);
	  break;
	    
	case REPLACE_INDEXED:
	  replace_indexed_pixels (s1, s, d, m, opacity,
				  affect, src1->w, src1->bytes,
				  src2->bytes, has_alpha1, has_alpha2);
	  break;
	    
	case ERASE_INTEN:
	  erase_inten_pixels (s1, s, d, m, opacity,
			      affect, src1->w, src1->bytes);
	  break;
	    
	case ERASE_INDEXED:
	  erase_indexed_pixels (s1, s, d, m, opacity,
				affect, src1->w, src1->bytes);
	  break;
	    
	case ANTI_ERASE_INTEN:
	  anti_erase_inten_pixels (s1, s, d, m, opacity,
				   affect, src1->w, src1->bytes);
	  break;
	    
	case ANTI_ERASE_INDEXED:
	  anti_erase_indexed_pixels (s1, s, d, m, opacity,
				     affect, src1->w, src1->bytes);
	  break;
	    
	case NO_COMBINATION:
	  g_warning("NO_COMBINATION");
	  break;
	    
	default:
	  g_warning("UNKNOWN COMBINATION");
	  break;
	}
    
    next_row:
      s1 += src1->rowstride;
      s2 += src2->rowstride;
      d += dest->rowstride;
      if (mask)
	m += mask->rowstride;
    }
}


void
combine_regions (PixelRegion	  *src1,
		 PixelRegion	  *src2,
		 PixelRegion   	  *dest,
		 PixelRegion  	  *mask,
		 guchar	          *data,
		 gint		   opacity,
		 LayerModeEffects  mode,
		 gboolean         *affect,
		 gint		   type)
{
  gboolean has_alpha1, has_alpha2;
  gint i;
  struct combine_regions_struct st;

  /*  Determine which sources have alpha channels  */
  switch (type)
    {
    case COMBINE_INTEN_INTEN:
    case COMBINE_INDEXED_INDEXED:
      has_alpha1 = has_alpha2 = FALSE;
      break;
    case COMBINE_INTEN_A_INTEN:
      has_alpha1 = TRUE;
      has_alpha2 = FALSE;
      break;
    case COMBINE_INTEN_INTEN_A:
    case COMBINE_INDEXED_INDEXED_A:
      has_alpha1 = FALSE;
      has_alpha2 = TRUE;
      break;
    case COMBINE_INTEN_A_INTEN_A:
    case COMBINE_INDEXED_A_INDEXED_A:
      has_alpha1 = has_alpha2 = TRUE;
      break;
    default:
      has_alpha1 = has_alpha2 = FALSE;
    }

  st.opacity    = opacity;
  st.mode       = mode;
  st.affect     = affect;
  st.type       = type;
  st.data       = data;
  st.has_alpha1 = has_alpha1;
  st.has_alpha2 = has_alpha2;

  /* cheap and easy when the row of src2 is completely opaque/transparent
     and the wind is otherwise blowing in the right direction.
  */

  /* First check - we can't do an opacity quickskip if the drawable
     has a mask, or non-full opacity, or the layer mode dictates
     that we might gain transparency.
  */
  st.opacity_quickskip_possible = ((!mask)                               && 
				   (opacity == 255)                      &&
				   (!layer_modes[mode].decrease_opacity) &&
				   (layer_modes[mode].affect_alpha       &&
				    has_alpha1                           &&
				    affect[src1->bytes - 1]));

  /* Second check - if any single colour channel can't be affected,
     we can't use the opacity quickskip.
  */
  if (st.opacity_quickskip_possible)
    {
      for (i = 0; i < src1->bytes - 1; i++)
	{
	  if (!affect[i])
	    {
	      st.opacity_quickskip_possible = FALSE;
	      break;
	    }
	}
    }

  /* transparency quickskip is only possible if the layer mode
     dictates that we cannot possibly gain opacity, or the 'overall'
     opacity of the layer is set to zero anyway.
   */
  st.transparency_quickskip_possible = ((!layer_modes[mode].increase_opacity)
					|| (opacity==0));

  /* Start the actual processing.
   */
  pixel_regions_process_parallel ((p_func)combine_sub_region, &st, 4,
				    src1, src2, dest, mask);
}

void
combine_regions_replace (PixelRegion *src1,
			 PixelRegion *src2,
			 PixelRegion *dest,
			 PixelRegion *mask,
			 guchar      *data,
			 gint         opacity,
			 gboolean    *affect,
			 gint         type)
{
  gint     h;
  guchar  *s1;
  guchar  *s2;
  guchar  *d;
  guchar  *m;
  gpointer pr;

  for (pr = pixel_regions_register (4, src1, src2, dest, mask);
       pr != NULL;
       pr = pixel_regions_process (pr))
    {
      s1 = src1->data;
      s2 = src2->data;
      d = dest->data;
      m = mask->data;

      for (h = 0; h < src1->h; h++)
	{

	  /*  Now, apply the paint mode  */
	  apply_layer_mode_replace (s1, s2, d, m, src1->x, src1->y + h,
				    opacity, src1->w,
				    src1->bytes, src2->bytes, affect);

	  s1 += src1->rowstride;
	  s2 += src2->rowstride;
	  d += dest->rowstride;
	  m += mask->rowstride;
	}
    }
}

/************************************/
/*       apply layer modes          */
/************************************/

gint
apply_layer_mode (guchar            *src1,
		  guchar            *src2,
		  guchar           **dest,
		  gint               x,
		  gint               y,
		  gint               opacity,
		  gint               length,
		  LayerModeEffects   mode,
		  gint               bytes1, 
		  gint               bytes2, 
		  gboolean           has_alpha1, 
		  gboolean           has_alpha2,
		  gint              *mode_affect)
{
  gint combine;

  if (!has_alpha1 && !has_alpha2)
    combine = COMBINE_INTEN_INTEN;
  else if (!has_alpha1 && has_alpha2)
    combine = COMBINE_INTEN_INTEN_A;
  else if (has_alpha1 && !has_alpha2)
    combine = COMBINE_INTEN_A_INTEN;
  else
    combine = COMBINE_INTEN_A_INTEN_A;

  /*  assumes we're applying src2 TO src1  */
  switch (mode)
    {
    case NORMAL_MODE:
      *dest = src2;
      break;

    case DISSOLVE_MODE:
      /*  Since dissolve requires an alpha channels...  */
      if (! has_alpha2)
	add_alpha_pixels (src2, *dest, length, bytes2);

      dissolve_pixels (src2, *dest, x, y, opacity, length, bytes2,
		       ((has_alpha2) ? bytes2 : bytes2 + 1), has_alpha2);
      combine = (has_alpha1) ? COMBINE_INTEN_A_INTEN_A : COMBINE_INTEN_INTEN_A;
      break;

    case MULTIPLY_MODE:
      multiply_pixels (src1, src2, *dest, length, bytes1, bytes2, has_alpha1, has_alpha2);
      break;

    case DIVIDE_MODE:
      divide_pixels (src1, src2, *dest, length, bytes1, bytes2, has_alpha1, has_alpha2);
      break;

    case SCREEN_MODE:
      screen_pixels (src1, src2, *dest, length, bytes1, bytes2, has_alpha1, has_alpha2);
      break;

    case OVERLAY_MODE:
      overlay_pixels (src1, src2, *dest, length, bytes1, bytes2, has_alpha1, has_alpha2);
      break;

    case DIFFERENCE_MODE:
      difference_pixels (src1, src2, *dest, length, bytes1, bytes2, has_alpha1, has_alpha2);
      break;

    case ADDITION_MODE:
      add_pixels (src1, src2, *dest, length, bytes1, bytes2, has_alpha1, has_alpha2);
      break;

    case SUBTRACT_MODE:
      subtract_pixels (src1, src2, *dest, length, bytes1, bytes2, has_alpha1, has_alpha2);
      break;

    case DARKEN_ONLY_MODE:
      darken_pixels (src1, src2, *dest, length, bytes1, bytes2, has_alpha1, has_alpha2);
      break;

    case LIGHTEN_ONLY_MODE:
      lighten_pixels (src1, src2, *dest, length, bytes1, bytes2, has_alpha1, has_alpha2);
      break;

    case HUE_MODE: case SATURATION_MODE: case VALUE_MODE:
      /*  only works on RGB color images  */
      if (bytes1 > 2)
	hsv_only_pixels (src1, src2, *dest, mode, length, bytes1, bytes2, has_alpha1, has_alpha2);
      else
	*dest = src2;
      break;

    case COLOR_MODE:
      /*  only works on RGB color images  */
      if (bytes1 > 2)
	color_only_pixels (src1, src2, *dest, mode, length, bytes1, bytes2, has_alpha1, has_alpha2);
      else
	*dest = src2;
      break;

    case BEHIND_MODE:
      *dest = src2;
      if (has_alpha1)
	combine = BEHIND_INTEN;
      else
	combine = NO_COMBINATION;
      break;

    case REPLACE_MODE:
      *dest = src2;
      combine = REPLACE_INTEN;
      break;

    case ERASE_MODE:
      *dest = src2;
      /*  If both sources have alpha channels, call erase function.
       *  Otherwise, just combine in the normal manner
       */
      combine = (has_alpha1 && has_alpha2) ? ERASE_INTEN : combine;
      break;

    case ANTI_ERASE_MODE:
      *dest = src2;
      combine = (has_alpha1 && has_alpha2) ? ANTI_ERASE_INTEN : combine;
      break;

    case DODGE_MODE:
      dodge_pixels (src1, src2, *dest, length, bytes1, bytes2, has_alpha1, has_alpha2);
      break;

    case BURN_MODE:
      burn_pixels (src1, src2, *dest, length, bytes1, bytes2, has_alpha1, has_alpha2);
      break;

    case HARDLIGHT_MODE:
      hardlight_pixels (src1, src2, *dest, length, bytes1, bytes2, has_alpha1, has_alpha2);
      break;

    default :
      break;
    }

  /*  Determine whether the alpha channel of the destination can be affected
   *  by the specified mode--This keeps consistency with varying opacities
   */
  *mode_affect = layer_modes[mode].affect_alpha;

  return combine;
}


gint
apply_indexed_layer_mode (guchar            *src1,
			  guchar            *src2,
			  guchar           **dest,
			  LayerModeEffects   mode,
			  gboolean           has_alpha1, /* has alpha */
			  gboolean           has_alpha2) /* has alpha */
{
  gint combine;

  if (!has_alpha1 && !has_alpha2)
    combine = COMBINE_INDEXED_INDEXED;
  else if (!has_alpha1 && has_alpha2)
    combine = COMBINE_INDEXED_INDEXED_A;
  else if (has_alpha1 && has_alpha2)
    combine = COMBINE_INDEXED_A_INDEXED_A;
  else
    combine = NO_COMBINATION;

  /*  assumes we're applying src2 TO src1  */
  switch (mode)
    {
    case REPLACE_MODE:
      *dest = src2;
      combine = REPLACE_INDEXED;
      break;

    case BEHIND_MODE:
      *dest = src2;
      if (has_alpha1)
	combine = BEHIND_INDEXED;
      else
	combine = NO_COMBINATION;
      break;

    case ERASE_MODE:
      *dest = src2;
      /*  If both sources have alpha channels, call erase function.
       *  Otherwise, just combine in the normal manner
       */
      combine = (has_alpha1 && has_alpha2) ? ERASE_INDEXED : combine;
      break;

    default:
      break;
    }

  return combine;
}

static void
apply_layer_mode_replace (guchar   *src1,
			  guchar   *src2,
			  guchar   *dest,
			  guchar   *mask,
			  gint      x,
			  gint      y,
			  gint      opacity,
			  gint      length,
			  gint      bytes1,
			  gint      bytes2,
			  gboolean *affect)
{
  replace_pixels (src1, src2, dest, mask, length, opacity, affect, bytes1, bytes2);
}