/* The GIMP -- an image manipulation program
 * Copyright (C) 1995 Spencer Kimball and Peter Mattis
 *
 * gimplut.c: Copyright (C) 1999 Jay Cox <jaycox@earthlink.net>
 *
 * 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 "gimplutP.h"
#include "gimplut.h"
#include <stdio.h>

GimpLut *
gimp_lut_new ()
{
 GimpLut *lut;
 lut = g_new(GimpLut, 1);
 lut->luts = NULL;
 lut->nchannels = 0;
 return lut;
}

void
gimp_lut_free (GimpLut *lut)
{
  int i;
  for (i = 0; i < lut->nchannels; i++)
    g_free(lut->luts[i]);
  if (lut->luts)
    g_free(lut->luts);
}

void
gimp_lut_setup (GimpLut     *lut, 
		GimpLutFunc  func,
		void        *user_data, 
		int          nchannels)
{
  int i, v;
  double val;
  if (lut->luts)
  {
    for (i = 0; i < lut->nchannels; i++)
      g_free(lut->luts[i]);
    g_free(lut->luts);
  }
  lut->nchannels = nchannels;
  lut->luts = g_new(unsigned char*, lut->nchannels);
  for (i = 0; i < lut->nchannels; i++)
  {
    lut->luts[i] = g_new(unsigned char, 256);
    for (v = 0; v < 256; v++)
    { /* to add gamma correction use func(v ^ g) ^ 1/g instead. */
      val = 255.0 * func(user_data, lut->nchannels, i, v/255.0) + 0.5;
      if (val < 0.0)
	lut->luts[i][v] = 0;
      else if (val >= 255.0)
	lut->luts[i][v] = 255;
      else
	lut->luts[i][v] = val;
    }
  }
}

void
gimp_lut_setup_exact (GimpLut     *lut, 
		      GimpLutFunc  func,
		      void        *user_data, 
		      int          nchannels)
{
  gimp_lut_setup(lut, func, user_data, nchannels);
}

void
gimp_lut_process (GimpLut     *lut,
		  PixelRegion *srcPR,
		  PixelRegion *destPR)
{
  int h, width, src_r_i, dest_r_i;
  unsigned char *src, *dest;
  unsigned char *lut0 = NULL, *lut1 = NULL, *lut2 = NULL, *lut3 = NULL;

  if (lut->nchannels > 0)
    lut0 = lut->luts[0];
  if (lut->nchannels > 1)
    lut1 = lut->luts[1];
  if (lut->nchannels > 2)
    lut2 = lut->luts[2];
  if (lut->nchannels > 3)
    lut3 = lut->luts[3];

  h = srcPR->h;
  src  = srcPR->data;
  dest = destPR->data;
  width = srcPR->w;
  src_r_i =  srcPR->rowstride  - (srcPR->bytes  * srcPR->w);
  dest_r_i = destPR->rowstride - (destPR->bytes * srcPR->w);

  if (src_r_i == 0 && dest_r_i == 0)
  {
    width *= h;
    h = 1;
  }
  while (h--)
  {
    switch (lut->nchannels)
    {
     case 1:
       while (width--)
       {
	 *dest = lut0[*src];
	 src++;
	 dest++;
       }
       break;
     case 2:
       while (width--)
       {
	 dest[0] = lut0[src[0]];
	 dest[1] = lut1[src[1]];
	 src  += 2;
	 dest += 2;
       }
       break;
     case 3:
       while (width--)
       {
	 dest[0] = lut0[src[0]];
	 dest[1] = lut1[src[1]];
	 dest[2] = lut2[src[2]];
	 src  += 3;
	 dest += 3;
       }
       break;
     case 4:
       while (width--)
       {
	 dest[0] = lut0[src[0]];
	 dest[1] = lut1[src[1]];
	 dest[2] = lut2[src[2]];
	 dest[3] = lut3[src[3]];
	 src  += 4;
	 dest += 4;
       }
       break;
     default:
       fprintf(stderr, "gimplut: Error: nchannels = %d\n", lut->nchannels);
    }
    width = srcPR->w;
    src  += src_r_i;
    dest += dest_r_i;
  }
}

void
gimp_lut_process_inline (GimpLut     *lut,
			 PixelRegion *srcPR)
{
  int h, width, src_r_i;
  unsigned char *src;
  unsigned char *lut0 = NULL, *lut1 = NULL, *lut2 = NULL, *lut3 = NULL;

  if (lut->nchannels > 0)
    lut0 = lut->luts[0];
  if (lut->nchannels > 1)
    lut1 = lut->luts[1];
  if (lut->nchannels > 2)
    lut2 = lut->luts[2];
  if (lut->nchannels > 3)
    lut3 = lut->luts[3];

  h = srcPR->h;
  src  = srcPR->data;
  width = srcPR->w;
  src_r_i =  srcPR->rowstride  - (srcPR->bytes  * srcPR->w);

  if (src_r_i == 0)
  {
    width *= h;
    h = 1;
  }
  while (h--)
  {
    switch (lut->nchannels)
    {
     case 1:
       while (width--)
       {
	 *src = lut0[*src];
	 src++;
       }
       break;
     case 2:
       while (width--)
       {
	 src[0] = lut0[src[0]];
	 src[1] = lut1[src[1]];
	 src  += 2;
       }
       break;
     case 3:
       while (width--)
       {
	 src[0] = lut0[src[0]];
	 src[1] = lut1[src[1]];
	 src[2] = lut2[src[2]];
	 src  += 3;
       }
       break;
     case 4:
       while (width--)
       {
	 src[0] = lut0[src[0]];
	 src[1] = lut1[src[1]];
	 src[2] = lut2[src[2]];
	 src[3] = lut3[src[3]];
	 src  += 4;
       }
       break;
     default:
       fprintf(stderr, "gimplut: Error: nchannels = %d\n", lut->nchannels);
    }
    width = srcPR->w;
    src  += src_r_i;
  }
}

void
gimp_lut_process_2 (PixelRegion *srcPR,
		    PixelRegion *destPR,
		    GimpLut     *lut)
{
  gimp_lut_process(lut, srcPR, destPR);
}