pnmoutline.c

   1 #include <pam.h>
   2 #include <string.h>
   3
   4 struct pam inpam, outpam;
   5 tuple *inrows[3];
   6 tuple *outrow;
   7
   8 void
   9 clear_inrow(struct pam *p, tuple *row)
  10 {
  11         int i, j;
  12
  13         for(i=0; i<p->width; i++)
  14                 for(j=0; j<3; j++)
  15                         row[i][j]=0;
  16 }
  17
  18 void
  19 clear_outrow(struct pam *p, tuple *row)
  20 {
  21         int i,j;
  22
  23         for(i=0; i<p->width; i++)
  24                 for(j=0; j<3; j++)
  25                         row[i][j]=p->maxval;
  26 }
  27
  28 int
  29 is_black(unsigned int row, unsigned int column)
  30 {
  31
  32         sample *s = inrows[row][column];
  33         if(s[0]==0 && s[1]==0 && s[2]==0) return ~0;
  34         else return 0;
  35 }
  36
  37 int
  38 is_edge(unsigned int column)
  39 {
  40         unsigned int n = 0;
  41         if(is_black(0,column)) n++;
  42         if(is_black(2,column)) n++;
  43         if(is_black(1,column-1)) n++;
  44         if(is_black(1,column+1)) n++;
  45         return n==2 || n==3;
  46 }
  47
  48 void
  49 set_white(unsigned int column)
  50 {
  51         sample *s = outrow[column];
  52         s[0]=255; s[1]=255; s[2]=255;
  53 }
  54
  55 void
  56 set_black(unsigned int column)
  57 {
  58         sample *s = outrow[column];
  59         s[0]=0; s[1]=0; s[2]=0;
  60 }
  61
  62 void
  63 copy_tuple(unsigned int column)
  64 {
  65         sample *src, *dest;
  66
  67         src = inrows[1][column];
  68         dest = outrow[column];
  69         dest[0] = src[0];
  70         dest[1] = src[1];
  71         dest[2] = src[2];
  72 }
  73
  74 void
  75 read_row(unsigned int q)
  76 {
  77         memcpy(inrows[0], inrows[1], outpam.width*sizeof(sample)*3);
  78         memcpy(inrows[1], inrows[2], outpam.width*sizeof(sample)*3);
  79         if(q) pnm_readpamrow(&inpam, inrows[2]+1);
  80         else clear_inrow(&outpam, inrows[2]);
  81 }
  82
  83
  84 int
  85 main(int argc, char **argv)
  86 {
  87         unsigned int row,column,i;
  88
  89         pnm_init(&argc, argv);
  90         pnm_readpaminit(stdin, &inpam, sizeof(struct pam));
  91
  92         outpam = inpam;
  93         outpam.width+=2; outpam.height+=2;
  94         outpam.file = stdout;
  95         pnm_writepaminit(&outpam);
  96
  97         outrow = pnm_allocpamrow(&outpam);
  98         for(i=0; i<3; i++) inrows[i] = pnm_allocpamrow(&outpam);
  99         for(i=0; i<3; i++) clear_inrow(&outpam, inrows[i]);
 100
 101         clear_outrow(&outpam, outrow);
 102         pnm_writepamrow(&outpam, inrows[0]);
 103
 104         pnm_readpamrow(&inpam, inrows[1]+1);
 105         for(row=0; row < inpam.height; row++) {
 106                 for(column=1; column<=inpam.width; column++) {
 107                         if(is_black(1,column)) {
 108                                 if(is_edge(column)) set_black(column);
 109                                 else set_white(column);
 110                         } else copy_tuple(column);
 111                 }
 112                 pnm_writepamrow(&outpam, outrow);
 113                 read_row(row != inpam.height-1);
 114         }
 115
 116         clear_outrow(&outpam, outrow);
 117         pnm_writepamrow(&outpam, inrows[2]);
 118
 119         pnm_freepamrow(outrow);
 120         for(i=0; i<3; i++) pnm_freepamrow(inrows[i]);
 121         return 0;
 122 }