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Diffstat (limited to 'editor/ppmshift.c')
| -rw-r--r-- | editor/ppmshift.c | 137 |
1 files changed, 137 insertions, 0 deletions
diff --git a/editor/ppmshift.c b/editor/ppmshift.c new file mode 100644 index 00000000..1f8a599b --- /dev/null +++ b/editor/ppmshift.c @@ -0,0 +1,137 @@ + +/*********************************************************************/ +/* 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 "ppm.h" + +/* global variables */ +#ifdef AMIGA +static char *version = "$VER: ppmshift 1.1 (16.11.93)"; /* Amiga version identification */ +#endif + +/**************************/ +/* start of main function */ +/**************************/ +int main(argc, argv) +int argc; +char *argv[]; +{ + FILE* ifp; + time_t timenow; + int argn, rows, cols, format, i = 0, j = 0; + pixel *srcrow, *destrow; + pixel *pP = NULL, *pP2 = NULL; + pixval maxval; + int shift, nowshift; + const char * const usage = "shift [ppmfile]\n shift: maximum number of pixels to shift a line by\n"; + + /* parse in 'default' parameters */ + ppm_init(&argc, argv); + + argn = 1; + + /* parse in shift number */ + if (argn == argc) + pm_usage(usage); + if (sscanf(argv[argn], "%d", &shift) != 1) + pm_usage(usage); + if (shift < 0) + pm_error("shift factor must be 0 or more"); + ++argn; + + /* parse in filename (if present, stdin otherwise) */ + if (argn != argc) + { + ifp = pm_openr(argv[argn]); + ++argn; + } + else + ifp = stdin; + + if (argn != argc) + pm_usage(usage); + + /* read first data from file */ + ppm_readppminit(ifp, &cols, &rows, &maxval, &format); + + if (shift > cols) + { + shift = cols; + pm_message("shift amount is larger than picture width - reset to %d", shift); + } + + /* no error checking required here, ppmlib does it all for us */ + srcrow = ppm_allocrow(cols); + + /* allocate a row of pixel data for the new pixels */ + destrow = ppm_allocrow(cols); + + ppm_writeppminit(stdout, cols, rows, maxval, 0); + + /* get time of day to feed the random number generator */ + timenow = time(NULL); + srand(timenow); + + /** 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 (i = 0; i < rows; i++) + { + if (shift != 0) + nowshift = (rand() % (shift+1)) - ((shift+1) / 2); + else + nowshift = 0; + + ppm_readppmrow(ifp, srcrow, cols, maxval, format); + + pP = srcrow; + pP2 = destrow; + + /* 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) + { + pP+= abs(nowshift); + for (j = 0; j < cols; j++) + { + PPM_ASSIGN(*pP2, PPM_GETR(*pP), PPM_GETG(*pP), PPM_GETB(*pP)); + pP2++; + if (j < (cols+nowshift)-1) + pP++; + } + } + /* if the shift value is 0 or positive, the first <nowshift> pixels of the */ + /* destination line are filled with the first pixel from the source line, */ + /* and the rest of the source line is copied to the dest line */ + else + { + for (j = 0; j < cols; j++) + { + PPM_ASSIGN(*pP2, PPM_GETR(*pP), PPM_GETG(*pP), PPM_GETB(*pP)); + pP2++; + if (j >= nowshift) + pP++; + } + } + + /* write out one line of graphic data */ + ppm_writeppmrow(stdout, destrow, cols, maxval, 0); + } + + pm_close(ifp); + ppm_freerow(srcrow); + ppm_freerow(destrow); + + exit(0); +} + |