/* ----------------------------------------------------------------------

 *

 * Convert a PAM image to an AVS X image

 *

 * By Scott Pakin <scott+pbm@pakin.org>

 *

 * ----------------------------------------------------------------------

 *

 * Copyright (C) 2010 Scott Pakin <scott+pbm@pakin.org>

 *

 * This program is free software: you can redistribute it and/or modify

 * it under the terms of the GNU General Public License as published by

 * the Free Software Foundation, either version 3 of the License, or (at

 * your option) any later version.

 *

 * This program is distributed in the hope that it will be useful, but

 * WITHOUT ANY WARRANTY; without even the implied warranty of

 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU

 * General Public License for more details.

 *

 * You should have received a copy of the GNU General Public License

 * along with this program.  If not, see http://www.gnu.org/licenses/.

 *

 * ----------------------------------------------------------------------

 */

#include <stdio.h>

#include "pm.h"

#include "pam.h"

static char

sample2char(sample const s,

            sample const maxval) {

/* Scale down a sample to a single byte. */

    return maxval==255 ? s : s * 255 / maxval;

}

#define THIS_SAMPLE_CHAR(PLANE) \

  sample2char(tuplerow[col][PLANE], pamP->maxval)

static void

produceAvs(struct pam * const pamP,

           FILE *       const avsFileP) {

    tuple * tuplerow;

    /* Write the AVS header (image width and height as 4-byte

       big-endian integers).

    */

    pm_writebiglong(avsFileP, pamP->width);

    pm_writebiglong(avsFileP, pamP->height);

    /* Write the AVS data (alpha, red, green, blue -- one byte apiece. */

    tuplerow = pnm_allocpamrow(pamP);

    switch (pamP->depth) {

    case 1: {

        /* Black-and-white or grayscale, no alpha */

        unsigned int row;

        for (row = 0; row < pamP->height; ++row) {

            unsigned int col;

            pnm_readpamrow(pamP, tuplerow);

            for (col = 0; col < pamP->width; ++col) {

                pm_writechar(avsFileP, (char)255);

                pm_writechar(avsFileP, THIS_SAMPLE_CHAR(0));

                pm_writechar(avsFileP, THIS_SAMPLE_CHAR(0));

                pm_writechar(avsFileP, THIS_SAMPLE_CHAR(0));

            }

        }

    } break;

    case 2: {

        /* Black-and-white or grayscale plus alpha */

        unsigned int row;

        for (row = 0; row < pamP->height; ++row) {

            unsigned int col;

            pnm_readpamrow(pamP, tuplerow);

            for (col = 0; col < pamP->width; ++col) {

                pm_writechar(avsFileP, THIS_SAMPLE_CHAR(1));

                pm_writechar(avsFileP, THIS_SAMPLE_CHAR(0));

                pm_writechar(avsFileP, THIS_SAMPLE_CHAR(0));

                pm_writechar(avsFileP, THIS_SAMPLE_CHAR(0));

            }

        }

    } break;

    case 3: {

        /* RGB, no alpha */

        unsigned int row;

        for (row = 0; row < pamP->height; ++row) {

            unsigned int col;

            pnm_readpamrow(pamP, tuplerow);

            for (col = 0; col < pamP->width; ++col) {

                pm_writechar(avsFileP, (char)255);

                pm_writechar(avsFileP, THIS_SAMPLE_CHAR(0));

                pm_writechar(avsFileP, THIS_SAMPLE_CHAR(1));

                pm_writechar(avsFileP, THIS_SAMPLE_CHAR(2));

            }

        }

    } break;

    case 4: {

        /* RGB plus alpha */

        unsigned int row;

        for (row = 0; row < pamP->height; ++row) {

            unsigned int col;

            pnm_readpamrow( pamP, tuplerow );

            for (col = 0; col < pamP->width; ++col) {

                pm_writechar(avsFileP, THIS_SAMPLE_CHAR(3));

                pm_writechar(avsFileP, THIS_SAMPLE_CHAR(0));

                pm_writechar(avsFileP, THIS_SAMPLE_CHAR(1));

                pm_writechar(avsFileP, THIS_SAMPLE_CHAR(2));

            }

        }

    } break;

    default:

        pm_error("Unrecognized PAM depth %u.  We understand only "

                 "1, 2, 3, and 4", pamP->depth);

        break;

    }

    pnm_freepamrow(tuplerow);

}

int

main(int argc, const char *argv[]) {

    struct pam   inPam;

    const char * inputFilename;

    FILE       * inFileP;

    pm_proginit(&argc, argv);

    inputFilename = (argc > 1) ? argv[1] : "-";

    inFileP = pm_openr(inputFilename);

    pnm_readpaminit(inFileP, &inPam, PAM_STRUCT_SIZE(tuple_type));

    produceAvs(&inPam, stdout);

    pm_closer(inFileP);

    return 0;

}