/* Libart_LGPL - library of basic graphic primitives
 * Copyright (C) 1998 Raph Levien
 *
 * This library is free software; you can redistribute it and/or
 * modify it under the terms of the GNU Library General Public
 * License as published by the Free Software Foundation; either
 * version 2 of the License, or (at your option) any later version.
 *
 * This library is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
 * Library General Public License for more details.
 *
 * You should have received a copy of the GNU Library General Public
 * License along with this library; if not, write to the
 * Free Software Foundation, Inc., 59 Temple Place - Suite 330,
 * Boston, MA 02111-1307, USA.
 */

#include "art_misc.h"
#include "art_uta.h"
#include "art_rect.h"
#include "art_rect_uta.h"

/* Functions to decompose a microtile array into a list of rectangles. */

/* Allocate a new list of rectangles, set *p_nrects to the number in
   the list.

   Each rectangle bounded in size by (max_width, max_height). However,
   these bounds must be at least the size of one tile.

   This routine provides a precise implementation, i.e. the rectangles
   cover exactly the same area as the uta. It is thus appropriate in
   cases where the overhead per rectangle is small compared with the
   cost of filling in extra pixels. */
ArtIRect *
art_rect_list_from_uta (ArtUta *uta, int max_width, int max_height,
			int *p_nrects)
{
  ArtIRect *rects;
  int n_rects, n_rects_max;
  int x, y;
  int width, height;
  int ix;
  int left_ix;
  ArtUtaBbox *utiles;
  ArtUtaBbox bb;
  int x0, y0, x1, y1;
  int *glom;
  int glom_rect;

  n_rects = 0;
  n_rects_max = 1;
  rects = art_new (ArtIRect, n_rects_max);

  width = uta->width;
  height = uta->height;
  utiles = uta->utiles;

  glom = art_new (int, width * height);
  for (ix = 0; ix < width * height; ix++)
    glom[ix] = -1;

  ix = 0;
  for (y = 0; y < height; y++)
    for (x = 0; x < width; x++)
      {
	bb = utiles[ix];
	if (bb)
	  {
	    x0 = ((uta->x0 + x) << ART_UTILE_SHIFT) + ART_UTA_BBOX_X0(bb);
	    y0 = ((uta->y0 + y) << ART_UTILE_SHIFT) + ART_UTA_BBOX_Y0(bb);
	    y1 = ((uta->y0 + y) << ART_UTILE_SHIFT) + ART_UTA_BBOX_Y1(bb);

	    left_ix = ix;
	    /* now try to extend to the right */
	    while (x != width - 1 &&
		   ART_UTA_BBOX_X1(bb) == ART_UTILE_SIZE &&
		   (((bb & 0xffffff) ^ utiles[ix + 1]) & 0xffff00ff) == 0 &&
		   (((uta->x0 + x + 1) << ART_UTILE_SHIFT) +
		    ART_UTA_BBOX_X1(utiles[ix + 1]) -
		    x0) <= max_width)
	      {
		bb = utiles[ix + 1];
		ix++;
		x++;
	      }
	    x1 = ((uta->x0 + x) << ART_UTILE_SHIFT) + ART_UTA_BBOX_X1(bb);


	    /* if rectangle nonempty */
	    if ((x1 ^ x0) | (y1 ^ y0))
	      {
		/* try to glom onto an existing rectangle */
		glom_rect = glom[left_ix];
		if (glom_rect != -1 &&
		    x0 == rects[glom_rect].x0 &&
		    x1 == rects[glom_rect].x1 &&
		    y0 == rects[glom_rect].y1 &&
		    y1 - rects[glom_rect].y0 <= max_height)
		  {
		    rects[glom_rect].y1 = y1;
		  }
		else
		  {
		    if (n_rects == n_rects_max)
		      art_expand (rects, ArtIRect, n_rects_max);
		    rects[n_rects].x0 = x0;
		    rects[n_rects].y0 = y0;
		    rects[n_rects].x1 = x1;
		    rects[n_rects].y1 = y1;
		    glom_rect = n_rects;
		    n_rects++;
		  }
		if (y != height - 1)
		  glom[left_ix + width] = glom_rect;
	      }
	  }
	ix++;
      }

  art_free (glom);
  *p_nrects = n_rects;
  return rects;
}