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/*********************************************************************/
/* ppmspread - randomly displace a PPM's pixels by a certain amount */
/* Frank Neumann, October 1993 */
/* V1.1 16.11.1993 */
/* */
/* version history: */
/* V1.0 12.10.1993 first version */
/* V1.1 16.11.1993 Rewritten to be NetPBM.programming conforming */
/*********************************************************************/
#include <string.h>
#include "nstring.h"
#include "rand.h"
#include "shhopt.h"
#include "ppm.h"
struct CmdlineInfo {
/* This structure represents all of the information the user
supplied in the command line but in a form that's easy for the
program to use.
*/
const char * inputFilename; /* '-' if stdin */
unsigned int spread;
unsigned int randomseedSpec;
unsigned int randomseed;
};
static void
parseCommandLine(int argc, const char ** const argv,
struct CmdlineInfo * const cmdlineP ) {
optEntry * option_def;
/* Instructions to OptParseOptions3 on how to parse our options */
optStruct3 opt;
unsigned int option_def_index;
MALLOCARRAY_NOFAIL(option_def, 100);
option_def_index = 0; /* Incremented by OPTENTRY */
OPTENT3(0, "randomseed", OPT_UINT, &cmdlineP->randomseed,
&cmdlineP->randomseedSpec, 0);
opt.opt_table = option_def;
opt.short_allowed = 0;
opt.allowNegNum = 1;
pm_optParseOptions3( &argc, (char **)argv, opt, sizeof(opt), 0 );
if (argc-1 < 1)
pm_error("You must specify the spread factor as an argument");
else {
const char * error;
pm_string_to_uint(argv[1], &cmdlineP->spread, &error);
if (error)
pm_error("Spread factor '%s' is not an unsigned integer. %s",
argv[1], error);
if (argc-1 < 2)
cmdlineP->inputFilename = "-";
else {
cmdlineP->inputFilename = argv[2];
if (argc-1 >2)
pm_error("Too many arguments: %u. "
"The only possible arguments are "
"the spread factor and the optional input file name",
argc-1);
}
}
}
static void
spreadRow(pixel ** const srcarray,
unsigned int const cols,
unsigned int const rows,
unsigned int const spread,
unsigned int const row,
pixel ** const destarray,
struct pm_randSt * const randStP) {
unsigned int col;
for (col = 0; col < cols; ++col) {
pixel const p = srcarray[row][col];
int const xdis = (pm_rand(randStP) % (spread + 1) )
- ((spread + 1) / 2);
int const ydis = (pm_rand(randStP) % (spread + 1))
- ((spread + 1) / 2);
int const xnew = col + xdis;
int const ynew = row + ydis;
/* only set the displaced pixel if it's within the bounds
of the image
*/
if (xnew >= 0 && xnew < cols && ynew >= 0 && ynew < rows) {
/* Displacing a pixel is accomplished by swapping it
with another pixel in its vicinity.
*/
pixel const p2 = srcarray[ynew][xnew];
/* Original value of second pixel */
/* Set second pixel to new value */
PPM_ASSIGN(destarray[ynew][xnew],
PPM_GETR(p), PPM_GETG(p), PPM_GETB(p));
/* Set first pixel to (old) value of second */
PPM_ASSIGN(destarray[row][col],
PPM_GETR(p2), PPM_GETG(p2), PPM_GETB(p2));
} else {
/* Displaced pixel is out of bounds; leave the old pixel there.
*/
PPM_ASSIGN(destarray[row][col],
PPM_GETR(p), PPM_GETG(p), PPM_GETB(p));
}
}
}
int
main(int argc,
const char * argv[]) {
struct CmdlineInfo cmdline;
FILE * ifP;
int rows, cols;
unsigned int row;
pixel ** destarray;
pixel ** srcarray;
pixval maxval;
struct pm_randSt randSt;
pm_proginit(&argc, argv);
parseCommandLine(argc, argv, &cmdline);
ifP = pm_openr(cmdline.inputFilename);
srcarray = ppm_readppm(ifP, &cols, &rows, &maxval);
destarray = ppm_allocarray(cols, rows);
pm_randinit(&randSt);
pm_srand2(&randSt, cmdline.randomseedSpec, cmdline.randomseed);
/* clear out the buffer */
for (row = 0; row < rows; ++row)
memset(destarray[row], 0, cols * sizeof(pixel));
/* Displace pixels */
for (row = 0; row < rows; ++row) {
spreadRow(srcarray, cols, rows, cmdline.spread, row,
destarray, &randSt);
}
pm_randterm(&randSt);
ppm_writeppm(stdout, destarray, cols, rows, maxval, 0);
pm_close(ifP);
ppm_freearray(srcarray, rows);
ppm_freearray(destarray, rows);
return 0;
}
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