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/* pbmpscale.c - pixel scaling with jagged edge smoothing.
* AJCD 13/8/90
*/
#include <stdio.h>
#include "pbm.h"
#include "mallocvar.h"
/* prototypes */
void nextrow_pscale ARGS((FILE *ifd, int row));
int corner ARGS((int pat));
/* input bitmap size and storage */
int rows, columns, format ;
bit *inrow[3] ;
#define thisrow (1)
/* compass directions from west clockwise */
int xd_pscale[] = { -1, -1, 0, 1, 1, 1, 0, -1 } ;
int yd_pscale[] = { 0, -1, -1, -1, 0, 1, 1, 1 } ;
/* starting positions for corners */
#define NE(f) ((f) & 3)
#define SE(f) (((f) >> 2) & 3)
#define SW(f) (((f) >> 4) & 3)
#define NW(f) (((f) >> 6) & 3)
typedef unsigned short sixteenbits ;
/* list of corner patterns; bit 7 is current color, bits 0-6 are squares
* around (excluding square behind), going clockwise.
* The high byte of the patterns is a mask, which determines which bits are
* not ignored.
*/
sixteenbits patterns[] = { 0x0000, 0xd555, /* no corner */
0x0001, 0xffc1, 0xd514, /* normal corner */
0x0002, 0xd554, 0xd515, /* reduced corners */
0xbea2, 0xdfc0, 0xfd81,
0xfd80, 0xdf80,
0x0003, 0xbfa1, 0xfec2 /* reduced if > 1 */
};
/* search for corner patterns, return type of corner found:
* 0 = no corner,
* 1 = normal corner,
* 2 = reduced corner,
* 3 = reduced if cutoff > 1
*/
int corner(pat)
int pat;
{
register int i, r=0;
for (i = 0; i < sizeof(patterns)/sizeof(sixteenbits); i++)
if (patterns[i] < 0x100)
r = patterns[i];
else if ((pat & (patterns[i] >> 8)) ==
(patterns[i] & (patterns[i] >> 8)))
return r;
return 0;
}
/* get a new row
*/
void nextrow_pscale(ifd, row)
FILE *ifd;
int row;
{
bit *shuffle = inrow[0] ;
inrow[0] = inrow[1];
inrow[1] = inrow[2];
inrow[2] = shuffle ;
if (row < rows) {
if (shuffle == NULL)
inrow[2] = shuffle = pbm_allocrow(columns);
pbm_readpbmrow(ifd, inrow[2], columns, format) ;
} else inrow[2] = NULL; /* discard storage */
}
int
main(argc, argv)
int argc;
char *argv[];
{
FILE *ifd;
register bit *outrow;
register int row, col, i, k;
int scale, cutoff, ucutoff ;
unsigned char *flags;
pbm_init( &argc, argv );
if (argc < 2)
pm_usage("scale [pbmfile]");
scale = atoi(argv[1]);
if (scale < 1)
pm_perror("bad scale (< 1)");
if (argc == 3)
ifd = pm_openr(argv[2]);
else
ifd = stdin ;
inrow[0] = inrow[1] = inrow[2] = NULL;
pbm_readpbminit(ifd, &columns, &rows, &format) ;
outrow = pbm_allocrow(columns*scale) ;
MALLOCARRAY(flags, columns);
if (flags == NULL)
pm_error("out of memory") ;
pbm_writepbminit(stdout, columns*scale, rows*scale, 0) ;
cutoff = scale / 2;
ucutoff = scale - 1 - cutoff;
nextrow_pscale(ifd, 0);
for (row = 0; row < rows; row++) {
nextrow_pscale(ifd, row+1);
for (col = 0; col < columns; col++) {
flags[col] = 0 ;
for (i = 0; i != 8; i += 2) {
int vec = inrow[thisrow][col] != PBM_WHITE;
for (k = 0; k < 7; k++) {
int x = col + xd_pscale[(k+i)&7] ;
int y = thisrow + yd_pscale[(k+i)&7] ;
vec <<= 1;
if (x >=0 && x < columns && inrow[y])
vec |= (inrow[y][x] != PBM_WHITE) ;
}
flags[col] |= corner(vec)<<i ;
}
}
for (i = 0; i < scale; i++) {
bit *ptr = outrow ;
int zone = (i > ucutoff) - (i < cutoff) ;
int cut = (zone < 0) ? (cutoff - i) :
(zone > 0) ? (i - ucutoff) : 0 ;
for (col = 0; col < columns; col++) {
int pix = inrow[thisrow][col] ;
int flag = flags[col] ;
int cutl, cutr ;
switch (zone) {
case -1:
switch (NW(flag)) {
case 0: cutl = 0; break;
case 1: cutl = cut; break;
case 2: cutl = cut ? cut-1 : 0; break;
case 3: cutl = (cut && cutoff > 1) ? cut-1 : cut; break;
default: cutl = 0; /* Should never reach here */
}
switch (NE(flag)) {
case 0: cutr = 0; break;
case 1: cutr = cut; break;
case 2: cutr = cut ? cut-1 : 0; break;
case 3: cutr = (cut && cutoff > 1) ? cut-1 : cut; break;
default: cutr = 0; /* Should never reach here */
}
break;
case 0:
cutl = cutr = 0;
break ;
case 1:
switch (SW(flag)) {
case 0: cutl = 0; break;
case 1: cutl = cut; break;
case 2: cutl = cut ? cut-1 : 0; break;
case 3: cutl = (cut && cutoff > 1) ? cut-1 : cut; break;
default: cutl = 0; /* should never reach here */
}
switch (SE(flag)) {
case 0: cutr = 0; break;
case 1: cutr = cut; break;
case 2: cutr = cut ? cut-1 : 0; break;
case 3: cutr = (cut && cutoff > 1) ? cut-1 : cut; break;
default: cutr = 0; /* should never reach here */
}
break;
default: cutl = 0; cutr = 0; /* Should never reach here */
}
for (k = 0; k < cutl; k++) /* left part */
*ptr++ = !pix ;
for (k = 0; k < scale-cutl-cutr; k++) /* centre part */
*ptr++ = pix ;
for (k = 0; k < cutr; k++) /* right part */
*ptr++ = !pix ;
}
pbm_writepbmrow(stdout, outrow, scale*columns, 0) ;
}
}
pm_close(ifd);
exit(0);
}
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