/* 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 <glib-object.h>

#include "base-types.h"

#include "brush-scale.h"
#include "temp-buf.h"


MaskBuf *
brush_scale_mask (MaskBuf *brush_mask,
                  gint     dest_width,
                  gint     dest_height)
{
  MaskBuf *scale_brush;
  gint     src_width;
  gint     src_height;
  gint     value;
  gint     area;
  gint     i, j;
  gint     x, x0, y, y0;
  gint     dx, dx0, dy, dy0;
  gint     fx, fx0, fy, fy0;
  guchar  *src, *dest;

  g_return_val_if_fail (brush_mask != NULL &&
                        dest_width != 0 && dest_height != 0, NULL);

  src_width  = brush_mask->width;
  src_height = brush_mask->height;

  scale_brush = mask_buf_new (dest_width, dest_height);
  g_return_val_if_fail (scale_brush != NULL, NULL);

  /*  get the data  */
  dest = mask_buf_data (scale_brush);
  src  = mask_buf_data (brush_mask);

  fx = fx0 = (256.0 * src_width) / dest_width;
  fy = fy0 = (256.0 * src_height) / dest_height;
  area = (fx0 * fy0) >> 8;

  x = x0 = 0;
  y = y0 = 0;
  dx = dx0 = 0;
  dy = dy0 = 0;

  for (i=0; i<dest_height; i++)
    {
      for (j=0; j<dest_width; j++)
        {
          value  = 0;

          fy = fy0;
          y  = y0;
          dy = dy0;

          if (dy)
            {
              fx = fx0;
              x  = x0;
              dx = dx0;

              if (dx)
                {
                  value += (dx * dy * src[x + src_width * y]) >> 8;
                  x++;
                  fx -= dx;
                  dx = 0;
                }
              while (fx >= 256)
                {
                  value += dy * src[x + src_width * y];
                  x++;
                  fx -= 256;
                }
              if (fx)
                {
                  value += fx * dy * src[x + src_width * y] >> 8;
                  dx = 256 - fx;
                }
              y++;
              fy -= dy;
              dy = 0;
            }

          while (fy >= 256)
            {
              fx = fx0;
              x  = x0;
              dx = dx0;

              if (dx)
                {
                  value += dx * src[x + src_width * y];
                  x++;
                  fx -= dx;
                  dx = 0;
                }
              while (fx >= 256)
                {
                  value += 256 * src[x + src_width * y];
                  x++;
                  fx -= 256;
                }
              if (fx)
                {
                  value += fx * src[x + src_width * y];
                  dx = 256 - fx;
                }
              y++;
              fy -= 256;
            }

          if (fy)
            {
              fx = fx0;
              x  = x0;
              dx = dx0;

              if (dx)
                {
                  value += (dx * fy * src[x + src_width * y]) >> 8;
                  x++;
                  fx -= dx;
                  dx = 0;
                }
              while (fx >= 256)
                {
                  value += fy * src[x + src_width * y];
                  x++;
                  fx -= 256;
                }
              if (fx)
                {
                  value += (fx * fy * src[x + src_width * y]) >> 8;
                  dx = 256 - fx;
                }
              dy = 256 - fy;
            }

          *dest++ = MIN ((value / area), 255);

          x0  = x;
          dx0 = dx;
        }
      x0  = 0;
      dx0 = 0;
      y0  = y;
      dy0 = dy;
    }

  return scale_brush;
}


#define ADD_RGB(dest, factor, src) \
  dest[0] += factor * src[0]; \
  dest[1] += factor * src[1]; \
  dest[2] += factor * src[2];

MaskBuf *
brush_scale_pixmap (MaskBuf *pixmap,
                    gint     dest_width,
                    gint     dest_height)
{
  MaskBuf *scale_brush;
  gint     src_width;
  gint     src_height;
  gint     value[3];
  gint     factor;
  gint     area;
  gint     i, j;
  gint     x, x0, y, y0;
  gint     dx, dx0, dy, dy0;
  gint     fx, fx0, fy, fy0;
  guchar  *src, *src_ptr, *dest;

  g_return_val_if_fail (pixmap != NULL && pixmap->bytes == 3 &&
                        dest_width != 0 && dest_height != 0, NULL);

  src_width  = pixmap->width;
  src_height = pixmap->height;

  scale_brush = temp_buf_new (dest_width, dest_height, 3, 0, 0, NULL);
  g_return_val_if_fail (scale_brush != NULL, NULL);

  /*  get the data  */
  dest = mask_buf_data (scale_brush);
  src  = mask_buf_data (pixmap);

  fx = fx0 = (256.0 * src_width) / dest_width;
  fy = fy0 = (256.0 * src_height) / dest_height;
  area = (fx0 * fy0) >> 8;

  x = x0 = 0;
  y = y0 = 0;
  dx = dx0 = 0;
  dy = dy0 = 0;

  for (i=0; i<dest_height; i++)
    {
      for (j=0; j<dest_width; j++)
        {
          value[0] = 0;
          value[1] = 0;
          value[2] = 0;

          fy = fy0;
          y  = y0;
          dy = dy0;

          if (dy)
            {
              fx = fx0;
              x  = x0;
              dx = dx0;

              if (dx)
                {
                  factor = (dx * dy) >> 8;
                  src_ptr = src + 3 * (x + y * src_width);
                  ADD_RGB (value, factor, src_ptr);
                  x++;
                  fx -= dx;
                  dx = 0;
                }
              while (fx >= 256)
                {
                  factor = dy;
                  src_ptr = src + 3 * (x + y * src_width);
                  ADD_RGB (value, factor, src_ptr);
                  x++;
                  fx -= 256;
                }
              if (fx)
                {
                  factor = (fx * dy) >> 8;
                  src_ptr = src + 3 * (x + y * src_width);
                  ADD_RGB (value, factor, src_ptr);
                  dx = 256 - fx;
                }
              y++;
              fy -= dy;
              dy = 0;
            }

          while (fy >= 256)
            {
              fx = fx0;
              x  = x0;
              dx = dx0;

              if (dx)
                {
                  factor = dx;
                  src_ptr = src + 3 * (x + y * src_width);
                  ADD_RGB (value, factor, src_ptr);
                  x++;
                  fx -= dx;
                  dx = 0;
                }
              while (fx >= 256)
                {
                  factor = 256;
                  src_ptr = src + 3 * (x + y * src_width);
                  ADD_RGB (value, factor, src_ptr);
                  x++;
                  fx -= 256;
                }
              if (fx)
                {
                  factor = fx;
                  src_ptr = src + 3 * (x + y * src_width);
                  ADD_RGB (value, factor, src_ptr);
                  dx = 256 - fx;
                }
              y++;
              fy -= 256;
            }

          if (fy)
            {
              fx = fx0;
              x  = x0;
              dx = dx0;

              if (dx)
                {
                  factor = (dx * fy) >> 8;
                  src_ptr = src + 3 * (x + y * src_width);
                  ADD_RGB (value, factor, src_ptr);
                  x++;
                  fx -= dx;
                  dx = 0;
                }
              while (fx >= 256)
                {
                  factor = fy;
                  src_ptr = src + 3 * (x + y * src_width);
                  ADD_RGB (value, factor, src_ptr);
                  x++;
                  fx -= 256;
                }
              if (fx)
                {
                  factor = (fx * fy) >> 8;
                  src_ptr = src + 3 * (x + y * src_width);
                  ADD_RGB (value, factor, src_ptr);
                  dx = 256 - fx;
                }
              dy = 256 - fy;
            }

          *dest++ = MIN ((value[0] / area), 255);
          *dest++ = MIN ((value[1] / area), 255);
          *dest++ = MIN ((value[2] / area), 255);

          x0  = x;
          dx0 = dx;
        }
      x0  = 0;
      dx0 = 0;
      y0  = y;
      dy0 = dy;
    }

  return scale_brush;
}

#undef ADD_RGB