wrlib/convolve.c

   1 /*
   2  * Raster graphics library
   3  *
   4  * Copyright (c) 1997-2003 Alfredo K. Kojima
   5  *
   6  *  This library is free software; you can redistribute it and/or
   7  *  modify it under the terms of the GNU Library General Public
   8  *  License as published by the Free Software Foundation; either
   9  *  version 2 of the License, or (at your option) any later version.
  10  *
  11  *  This library is distributed in the hope that it will be useful,
  12  *  but WITHOUT ANY WARRANTY; without even the implied warranty of
  13  *  MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
  14  *  Library General Public License for more details.
  15  *
  16  *  You should have received a copy of the GNU Library General Public
  17  *  License along with this library; if not, write to the Free
  18  *  Software Foundation, Inc., 51 Franklin St, Fifth Floor, Boston,
  19  *  MA 02110-1301, USA.
  20  */
  21
  22 #include <config.h>
  23
  24 #include <stdlib.h>
  25 #include <stdio.h>
  26 #include <string.h>
  27 #include <X11/Xlib.h>
  28 #include "wraster.h"
  29
  30 /*
  31  *----------------------------------------------------------------------
  32  * RBlurImage--
  33  *      Apply 3x3 1 1 1 low pass, convolution mask to image.
  34  *                1 2 1
  35  *                1 1 1 /10
  36  *----------------------------------------------------------------------
  37  */
  38 int RBlurImage(RImage * image)
  39 {
  40         register int x, y;
  41         register int tmp;
  42         unsigned char *ptr, *nptr;
  43         unsigned char *pptr = NULL, *tmpp;
  44         int ch = image->format == RRGBAFormat ? 4 : 3;
  45
  46         pptr = malloc(image->width * ch);
  47         if (!pptr) {
  48                 RErrorCode = RERR_NOMEMORY;
  49                 return False;
  50         }
  51 #define MASK(prev, cur, next, ch)\
  52     (*(prev-ch) + *prev + *(prev+ch)\
  53     +*(cur-ch) + 2 * *cur + *(cur+ch)\
  54     +*(next-ch) + *next + *(next+ch)) / 10
  55
  56         memcpy(pptr, image->data, image->width * ch);
  57
  58         ptr = image->data;
  59         nptr = ptr + image->width * ch;
  60         tmpp = pptr;
  61
  62         if (ch == 3) {
  63                 ptr += 3;
  64                 nptr += 3;
  65                 pptr += 3;
  66
  67                 for (y = 1; y < image->height - 1; y++) {
  68
  69                         for (x = 1; x < image->width - 1; x++) {
  70                                 tmp = *ptr;
  71                                 *ptr = MASK(pptr, ptr, nptr, 3);
  72                                 *pptr = tmp;
  73                                 ptr++;
  74                                 nptr++;
  75                                 pptr++;
  76
  77                                 tmp = *ptr;
  78                                 *ptr = MASK(pptr, ptr, nptr, 3);
  79                                 *pptr = tmp;
  80                                 ptr++;
  81                                 nptr++;
  82                                 pptr++;
  83
  84                                 tmp = *ptr;
  85                                 *ptr = MASK(pptr, ptr, nptr, 3);
  86                                 *pptr = tmp;
  87                                 ptr++;
  88                                 nptr++;
  89                                 pptr++;
  90                         }
  91                         pptr = tmpp;
  92                         ptr += 6;
  93                         nptr += 6;
  94                         pptr += 6;
  95                 }
  96         } else {
  97                 ptr += 4;
  98                 nptr += 4;
  99                 pptr += 4;
 100
 101                 for (y = 1; y < image->height - 1; y++) {
 102                         for (x = 1; x < image->width - 1; x++) {
 103                                 tmp = *ptr;
 104                                 *ptr = MASK(pptr, ptr, nptr, 4);
 105                                 *pptr = tmp;
 106                                 ptr++;
 107                                 nptr++;
 108                                 pptr++;
 109
 110                                 tmp = *ptr;
 111                                 *ptr = MASK(pptr, ptr, nptr, 4);
 112                                 *pptr = tmp;
 113                                 ptr++;
 114                                 nptr++;
 115                                 pptr++;
 116
 117                                 tmp = *ptr;
 118                                 *ptr = MASK(pptr, ptr, nptr, 4);
 119                                 *pptr = tmp;
 120                                 ptr++;
 121                                 nptr++;
 122                                 pptr++;
 123
 124                                 tmp = *ptr;
 125                                 *ptr = MASK(pptr, ptr, nptr, 4);
 126                                 *pptr = tmp;
 127                                 ptr++;
 128                                 nptr++;
 129                                 pptr++;
 130                         }
 131                         pptr = tmpp;
 132                         ptr += 8;
 133                         nptr += 8;
 134                         pptr += 8;
 135                 }
 136         }
 137
 138         return True;
 139 }
 140