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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"
/* 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)
#define MAX(x,y) ((x) > (y) ? (x) : (y))
static void
validateComputableDimensions(unsigned int const width,
unsigned int const height,
unsigned int const scaleFactor) {
/*----------------------------------------------------------------------------
Make sure that multiplication for output image width and height do not
overflow.
See validateComputetableSize() in libpam.c
and pbm_readpbminitrest() in libpbm2.c
-----------------------------------------------------------------------------*/
unsigned int const maxWidthHeight = INT_MAX - 2;
unsigned int const maxScaleFactor = maxWidthHeight / MAX(height, width);
if (scaleFactor > maxScaleFactor)
pm_error("Scale factor '%u' too large. "
"The maximum for this %u x %u input image is %u.",
scaleFactor, width, height, maxScaleFactor);
}
static int corner(uint16_t const pat) {
/* 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.
*/
uint16_t const patterns[]
= { 0x0000, 0xd555, /* no corner */
0x0001, 0xffc1, 0xd514, /* normal corner */
0x0002, 0xd554, 0xd515, 0xbea2, 0xdfc0, 0xfd81, 0xfd80, 0xdf80,
/* reduced corners */
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 i, r=0;
for (i = 0; i < sizeof(patterns)/sizeof(uint16_t); 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 */
static void nextrow_pscale(FILE * const ifd, int const 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(int argc, char ** argv) {
FILE * ifP;
bit * outrow;
unsigned int row;
int scale, outcols, outrows, cutoff, ucutoff ;
unsigned char *flags;
pbm_init( &argc, argv );
if (argc < 2)
pm_usage("scale [pbmfile]");
scale = atoi(argv[1]);
if (scale < 1)
pm_error("Scale argument must be at least one. You specified '%s'",
argv[1]);
if (argc == 3)
ifP = pm_openr(argv[2]);
else
ifP = stdin ;
inrow[0] = inrow[1] = inrow[2] = NULL;
pbm_readpbminit(ifP, &columns, &rows, &format) ;
validateComputableDimensions(columns, rows, scale);
outcols= columns * scale; outrows= rows * scale;
outrow = pbm_allocrow(outcols) ;
MALLOCARRAY(flags, columns);
if (flags == NULL)
pm_error("out of memory") ;
pbm_writepbminit(stdout, outcols, outrows, 0) ;
cutoff = scale / 2;
ucutoff = scale - 1 - cutoff;
nextrow_pscale(ifP, 0);
for (row = 0; row < rows; ++row) {
unsigned int col;
unsigned int i;
nextrow_pscale(ifP, row+1);
for (col = 0; col < columns; ++col) {
unsigned int i, k;
uint16_t thispoint = (inrow[thisrow][col] != PBM_WHITE) << 7;
unsigned char vec = 0;
for (k = 0; k < 8; ++k) {
int x = col + xd_pscale[k] ;
int y = thisrow + yd_pscale[k] ;
vec <<= 1;
if (x >=0 && x < columns && inrow[y])
vec |= (inrow[y][x] != PBM_WHITE) ;
}
vec = (vec >>1 | vec <<7);
flags[col] = 0 ;
for (i = 0; i != 8; i += 2) {
flags[col] |= corner(thispoint | (vec & 0x7f) )<<i ;
vec = ( vec >>6 | vec <<2);
}
}
for (i = 0; i < scale; i++) {
int const zone = (i > ucutoff) - (i < cutoff) ;
int const cut = (zone < 0) ? (cutoff - i) :
(zone > 0) ? (i - ucutoff) : 0 ;
unsigned int outcol=0;
for (col = 0; col < columns; ++col) {
int const pix = inrow[thisrow][col] ;
int const 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 */
}
{
unsigned int k;
for (k = 0; k < cutl; ++k) /* left part */
outrow[outcol++] = !pix ;
for (k = 0; k < scale-cutl-cutr; ++k) /* center part */
outrow[outcol++] = pix ;
for (k = 0; k < cutr; ++k) /* right part */
outrow[outcol++] = !pix ;
}
}
pbm_writepbmrow(stdout, outrow, scale*columns, 0) ;
}
}
pm_close(ifP);
return 0;
}
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