libs/gfx/algo/FillRing.algo.h

   1 /*****************************************************************************
   2  * This file is part of gfxprim library.                                     *
   3  *                                                                           *
   4  * Gfxprim is free software; you can redistribute it and/or                  *
   5  * modify it under the terms of the GNU Lesser General Public                *
   6  * License as published by the Free Software Foundation; either              *
   7  * version 2.1 of the License, or (at your option) any later version.        *
   8  *                                                                           *
   9  * Gfxprim is distributed in the hope that it will be useful,                *
  10  * but WITHOUT ANY WARRANTY; without even the implied warranty of            *
  11  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU         *
  12  * Lesser General Public License for more details.                           *
  13  *                                                                           *
  14  * You should have received a copy of the GNU Lesser General Public          *
  15  * License along with gfxprim; if not, write to the Free Software            *
  16  * Foundation, Inc., 51 Franklin Street, Fifth Floor,                        *
  17  * Boston, MA  02110-1301  USA                                               *
  18  *                                                                           *
  19  * Copyright (C) 2009-2010 Jiri "BlueBear" Dluhos                            *
  20  *                         <jiri.bluebear.dluhos@gmail.com>                  *
  21  *                                                                           *
  22  * Copyright (C) 2009-2012 Cyril Hrubis <metan@ucw.cz>                       *
  23  *                                                                           *
  24  *****************************************************************************/
  25
  26 /*
  27  * A filled ring drawing algorithm.
  28  */
  29
  30 /*
  31  * This macro defines a filled circle drawing function.
  32  * Arguments:
  33  *     PIXMAP_T - user-defined type of drawing pixmap (passed to HLINE)
  34  *     PIXVAL_T  - user-defined pixel value type (passed to HLINE)
  35  *     HLINE     - horizontal line drawing function f(pixmap, x0, x1, y, pixval)
  36  *     FN_NAME   - name of the function to be defined
  37  */
  38 #define DEF_FILLRING_FN(FN_NAME, PIXMAP_T, PIXVAL_T, HLINE) \
  39 static void FN_NAME(PIXMAP_T pixmap, int xcenter, int ycenter, \
  40         unsigned int r1, unsigned int r2, PIXVAL_T pixval) \
  41 { \
  42         int outer_r = (int) GP_MAX(r1, r2); \
  43         int inner_r = (int) GP_MIN(r1, r2); \
  44         int outer_x = 0; \
  45         int inner_x = 0; \
  46         int y; \
  47         int outer_error = -outer_r; \
  48         int inner_error = -inner_r; \
  49         for (y = outer_r; y >= 0; y--) { \
  50 \
  51                 while (outer_error < 0) { \
  52                         outer_error += 2*outer_x + 1; \
  53                         outer_x++; \
  54                 } \
  55                 outer_error += -2*y + 1; \
  56 \
  57                 if (y < inner_r && y > -inner_r) { \
  58                         while (inner_error < 0) { \
  59                                 inner_error += 2*inner_x + 1; \
  60                                 inner_x++; \
  61                         } \
  62                         inner_error += -2*y + 1; \
  63 \
  64                         HLINE(pixmap, xcenter - outer_x + 1, xcenter - inner_x,     ycenter - y, pixval); \
  65                         HLINE(pixmap, xcenter + inner_x,     xcenter + outer_x - 1, ycenter - y, pixval); \
  66                         HLINE(pixmap, xcenter - outer_x + 1, xcenter - inner_x,     ycenter + y, pixval); \
  67                         HLINE(pixmap, xcenter + inner_x,     xcenter + outer_x - 1, ycenter + y, pixval); \
  68                 } else { \
  69                         HLINE(pixmap, xcenter - outer_x + 1, xcenter + outer_x - 1, ycenter-y, pixval); \
  70                         HLINE(pixmap, xcenter - outer_x + 1, xcenter + outer_x - 1, ycenter+y, pixval); \
  71                 } \
  72         } \
  73 }