plugins/libwmfun/bilinear.c

   1 /*
   2  *  libwmfun - WindowMaker texture function library
   3  *  Copyright (C) 1999 Tobias Gloth
   4  *
   5  *  This program is free software; you can redistribute it and/or modify
   6  *  it under the terms of the GNU General Public License as published by
   7  *  the Free Software Foundation; either version 2 of the License, or
   8  *  (at your option) any later version.
   9  *
  10  *  This program is distributed in the hope that it will be useful,
  11  *  but WITHOUT ANY WARRANTY; without even the implied warranty of
  12  *  MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  13  *  GNU General Public License for more details.
  14  *
  15  *  You should have received a copy of the GNU General Public License
  16  *  along with this program; if not, write to the Free Software
  17  *  Foundation, Inc., 59 Temple Place - Suite 330, Boston, MA 02111-1307,
  18  *  USA.
  19  */
  20
  21 /*
  22  * $Id$
  23  *
  24  * $Log$
  25  * Revision 1.1  2000/12/03 18:58:41  id
  26  * initiate plugins branch
  27  *
  28  * Revision 1.1.1.1  1999/02/21 17:16:47  gloth
  29  * initial revision
  30  *
  31  */
  32
  33 #include "generic.h"
  34
  35 RImage *bilinear(int argc, char **argv, int width, int height, int relief)
  36 {
  37
  38         int color[4][3];
  39         RImage *image;
  40         unsigned char *cptr;
  41         int i, j, k;
  42
  43         argc--;
  44         argv++;
  45
  46         if (!start_image("bilinear", argc, 4, 5, width, height, &image)) {
  47                 return (RImage *) 0;
  48         }
  49
  50         for (i = 0; i < 4; i++) {
  51                 if (!parse_color(argv[i], color[i])) {
  52                         error("can't parse color: \"%s\"\n", argv[i]);
  53                         return 0;
  54                 }
  55         }
  56
  57         cptr = image->data;
  58         for (i = 0; i < height; i++) {
  59                 int b = 0xff * i / height;
  60                 int t = 0xff - b;
  61
  62                 for (j = 0; j < width; j++) {
  63                         int r = 0xff * j / width;
  64                         int l = 0xff - r;
  65                         int f[4];
  66
  67                         f[0] = (l * t) >> 8;
  68                         f[1] = (r * t) >> 8;
  69                         f[2] = (l * b) >> 8;
  70                         f[3] = (r * b) >> 8;
  71
  72                         for (k = 0; k < 3; k++) {
  73                                 *cptr++ =
  74                                     (f[0] * color[0][k] +
  75                                      f[1] * color[1][k] + f[2] * color[2][k] + f[3] * color[3][k]) >> 8;
  76                         }
  77
  78                         if (RRGBAFormat == image->format)
  79                                 cptr++;
  80                 }
  81         }
  82         return image;
  83 }