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/*********************************************************************/
/* ppmshift - shift lines of a picture left or right by x pixels */
/* Frank Neumann, October 1993 */
/* V1.1 16.11.1993 */
/* */
/* version history: */
/* V1.0 11.10.1993 first version */
/* V1.1 16.11.1993 Rewritten to be NetPBM.programming conforming */
/*********************************************************************/
#include <stdbool.h>
#include "mallocvar.h"
#include "shhopt.h"
#include "ppm.h"
struct CmdlineInfo {
/* All the information the user supplied in the command line,
in a form easy for the program to use.
*/
const char * inputFileName;
unsigned int shift;
unsigned int seed;
};
static void
parseCommandLine(int argc, const char ** const argv,
struct CmdlineInfo * const cmdlineP) {
/*----------------------------------------------------------------------------
Note that the file spec array we return is stored in the storage that
was passed to us as the argv array.
-----------------------------------------------------------------------------*/
optEntry * option_def;
/* Instructions to OptParseOptions3 on how to parse our options. */
optStruct3 opt;
unsigned int option_def_index;
unsigned int seedSpec;
MALLOCARRAY(option_def, 100);
opt.opt_table = option_def;
opt.short_allowed = false; /* We have no short (old-fashioned) options */
opt.allowNegNum = true; /* We have no parms that are negative numbers */
option_def_index = 0; /* incremented by OPTENT3 */
OPTENT3(0, "seed", OPT_UINT, &cmdlineP->seed,
&seedSpec, 0);
pm_optParseOptions3(&argc, (char **)argv, opt, sizeof(opt), 0);
/* Uses and sets argc, argv, and some of *cmdlineP and others. */
if (!seedSpec)
cmdlineP->seed = pm_randseed();
if (argc-1 < 1)
pm_error("You must specify the shift factor as an argument");
else {
int const arg1 = atoi(argv[1]);
if (arg1 < 0)
pm_error("shift factor must be 0 or more");
cmdlineP->shift = arg1;
if (argc-1 < 2)
cmdlineP->inputFileName = "-";
else {
cmdlineP->inputFileName = argv[2];
if (argc-1 > 2)
pm_error("Too many arguments (%u). "
"Shift factor and input file name are the only "
"possible arguments", argc-1);
}
}
free(option_def);
}
int
main(int argc, const char ** argv) {
FILE * ifP;
struct CmdlineInfo cmdline;
int rows, cols, format;
pixval maxval;
pixel * srcrow;
pixel * destrow;
unsigned int row;
unsigned int shift;
/* parse in 'default' parameters */
pm_proginit(&argc, argv);
parseCommandLine(argc, argv, &cmdline);
srand(cmdline.seed);
ifP = pm_openr(cmdline.inputFileName);
/* read first data from file */
ppm_readppminit(ifP, &cols, &rows, &maxval, &format);
if (cmdline.shift > cols) {
shift = cols;
pm_message("shift amount is larger than picture width - reset to %u",
shift);
} else
shift = cmdline.shift;
srcrow = ppm_allocrow(cols);
destrow = ppm_allocrow(cols);
ppm_writeppminit(stdout, cols, rows, maxval, 0);
/** now do the shifting **/
/* the range by which a line is shifted lays in the range from */
/* -shift/2 .. +shift/2 pixels; however, within this range it is */
/* randomly chosen */
for (row = 0; row < rows; ++row) {
pixel * pP;
pixel * pP2;
unsigned int nowshift;
if (shift != 0)
nowshift = (rand() % (shift+1)) - ((shift+1) / 2);
else
nowshift = 0;
ppm_readppmrow(ifP, srcrow, cols, maxval, format);
pP = &srcrow[0];
pP2 = &destrow[0];
/* if the shift value is less than zero, we take the original
pixel line and copy it into the destination line translated
to the left by x pixels. The empty pixels on the right end
of the destination line are filled up with the pixel that
is the right-most in the original pixel line.
*/
if (nowshift < 0) {
unsigned int col;
pP += abs(nowshift);
for (col = 0; col < cols; ++col) {
PPM_ASSIGN(*pP2, PPM_GETR(*pP), PPM_GETG(*pP), PPM_GETB(*pP));
++pP2;
if (col < (cols + nowshift) - 1)
++pP;
}
} else {
unsigned int col;
/* The shift value is 0 or positive, so fill the first
<nowshift> pixels of the destination line with the
first pixel from the source line, and copy the rest of
the source line to the dest line
*/
for (col = 0; col < cols; ++col) {
PPM_ASSIGN(*pP2, PPM_GETR(*pP), PPM_GETG(*pP), PPM_GETB(*pP));
++pP2;
if (col >= nowshift)
++pP;
}
}
ppm_writeppmrow(stdout, destrow, cols, maxval, 0);
}
pm_close(ifP);
ppm_freerow(srcrow);
ppm_freerow(destrow);
return 0;
}
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