citerate.h

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/*
Copyright (C) 2000  Jeffrey S. Freedman

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.
*/

#ifndef INCL_CITERATE
#define INCL_CITERATE 1

/*
 *  Here's an iterator that takes a rectangle of tiles, and sequentially
 *  returns the interesection of that rectangle with each chunk that it
 *  touches.
 */
class Chunk_intersect_iterator
  {
  Rectangle tiles;    // Original rect, shifted -cx, -cy.
  int start_tx;     // Saves start of tx in tiles.
          // Chunk #'s covered:
  int startcx, stopcx, stopcy;
  int curcx, curcy;   // Next chunk to return.
public:
  Chunk_intersect_iterator(Rectangle t) : tiles(t),
      startcx(t.x/c_tiles_per_chunk),
      stopcx(INCR_CHUNK((t.x + t.w - 1)/c_tiles_per_chunk)),
      stopcy(INCR_CHUNK((t.y + t.h - 1)/c_tiles_per_chunk)),
      curcy(t.y/c_tiles_per_chunk)
    {
    curcx = startcx;
    tiles.shift(-curcx*c_tiles_per_chunk,-curcy*c_tiles_per_chunk);
    start_tx = tiles.x;
    if (t.x < 0 || t.y < 0)
      {   // Empty to begin with.
      curcx = stopcx;
      curcy = stopcy;
      }
    }
          // Intersect is ranged within chunk.
  int get_next(Rectangle& intersect, int& cx, int& cy)
    {
    if (curcx == stopcx)  // End of row?
      if (curcy == stopcy)
        return (0);
      else
        {
        tiles.y -= c_tiles_per_chunk;
        tiles.x = start_tx;
        curcy = INCR_CHUNK(curcy);
        curcx = startcx;
        }
    Rectangle cr(0, 0, c_tiles_per_chunk, c_tiles_per_chunk);
          // Intersect given rect. with chunk.
    intersect = cr.intersect(tiles);
    cx = curcx;
    cy = curcy;
    curcx = INCR_CHUNK(curcx);
    tiles.x -= c_tiles_per_chunk;
    return (1);
    }
  };

#endif

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