/*********************************************************************/
/* ppmtv -  make a 'look-alike ntsc' picture from a PPM file       */
/* 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 "ppm.h"

/**************************/
/* start of main function */
/**************************/
int
main(int argc, char * argv[]) {

    FILE* ifp;
    int argn, rows, cols, format, i = 0, j = 0;
    pixel *srcrow, *destrow;
    pixel *pP = NULL, *pP2 = NULL;
    pixval maxval;
    double dimfactor;
    long int longfactor;
    const char * const usage = "dimfactor [ppmfile]\n        dimfactor: 0.0 = total blackness, 1.0 = original picture\n";

    /* parse in 'default' parameters */
    ppm_init(&argc, argv);

    argn = 1;

    /* parse in dim factor */
    if (argn == argc)
        pm_usage(usage);
    if (sscanf(argv[argn], "%lf", &dimfactor) != 1)
        pm_usage(usage);
    if (dimfactor < 0.0 || dimfactor > 1.0)
        pm_error("dim factor must be in the range from 0.0 to 1.0 ");
    ++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);

    /* no error checking required here, ppmlib does it all for us */
    srcrow = ppm_allocrow(cols);

    longfactor = (long int) (dimfactor * 65536);

    /* allocate a row of pixel data for the new pixels */
    destrow = ppm_allocrow(cols);

    ppm_writeppminit(stdout, cols, rows, maxval, 0);

    /** now do the ntsc'ing (actually very similar to ppmdim) **/
    for (i = 0; i < rows; i++) {
        ppm_readppmrow(ifp, srcrow, cols, maxval, format);

        pP = srcrow;
        pP2 = destrow;

        for (j = 0; j < cols; j++) {
            /* every alternating row is left in unchanged condition */
            if (i & 1) {
                PPM_ASSIGN(*pP2, PPM_GETR(*pP), PPM_GETG(*pP), PPM_GETB(*pP));
            }
            /* and the other lines are dimmed to the specified factor */
            else {
                PPM_ASSIGN(*pP2, (PPM_GETR(*pP) * longfactor) >> 16,
                                 (PPM_GETG(*pP) * longfactor) >> 16,
                                 (PPM_GETB(*pP) * longfactor) >> 16);
            }
            pP++;
            pP2++;
        }

        /* 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);
}



