color_insrt.c

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/* This routine is public only because source is in different files.
 * It should NEVER be called directly.
 * It is used by G_add_color_rule() and G__read_old_colors().
 * These routines know when it is approriate to call this routine.
 */
#include <grass/gis.h>
#define umalloc(n) (unsigned char *) G_malloc((size_t)n)
#define urealloc(s,n) (unsigned char *) G_realloc(s,(size_t)n)

#define LIMIT(x) if (x < 0) x = 0; else if (x > 255) x = 255;

int G__insert_color_into_lookup(CELL cat,
                                int red, int grn, int blu,
                                struct _Color_Info_ *cp)
{
    long nalloc;
    long i;
    long newlen, curlen, gap;

    LIMIT(red);
    LIMIT(grn);
    LIMIT(blu);

    /* first color? */
    if (!cp->lookup.active) {
        cp->lookup.active = 1;
        cp->lookup.nalloc = 256;
        cp->lookup.red = umalloc(cp->lookup.nalloc);
        cp->lookup.grn = umalloc(cp->lookup.nalloc);
        cp->lookup.blu = umalloc(cp->lookup.nalloc);
        cp->lookup.set = umalloc(cp->lookup.nalloc);
        cp->max = cp->min = cat;
    }

    /* extend the color table? */
    else if (cat > cp->max) {
        curlen = cp->max - cp->min + 1;
        newlen = cat - cp->min + 1;
        nalloc = newlen;
        if (nalloc != (int)nalloc)      /* check for int overflow */
            return -1;

        if (nalloc > cp->lookup.nalloc) {
            while (cp->lookup.nalloc < nalloc)
                cp->lookup.nalloc += 256;
            nalloc = cp->lookup.nalloc;

            cp->lookup.red = urealloc((char *)cp->lookup.red, nalloc);
            cp->lookup.grn = urealloc((char *)cp->lookup.grn, nalloc);
            cp->lookup.blu = urealloc((char *)cp->lookup.blu, nalloc);
            cp->lookup.set = urealloc((char *)cp->lookup.set, nalloc);
        }

        /* fill in gap with white */
        for (i = curlen; i < newlen; i++) {
            cp->lookup.red[i] = 255;
            cp->lookup.grn[i] = 255;
            cp->lookup.blu[i] = 255;
            cp->lookup.set[i] = 0;
        }
        cp->max = cat;
    }
    else if (cat < cp->min) {
        curlen = cp->max - cp->min + 1;
        newlen = cp->max - cat + 1;
        gap = newlen - curlen;
        nalloc = newlen;
        if (nalloc != (int)nalloc)      /* check for int overflow */
            return -1;

        if (nalloc > cp->lookup.nalloc) {
            while (cp->lookup.nalloc < nalloc)
                cp->lookup.nalloc += 256;
            nalloc = cp->lookup.nalloc;

            cp->lookup.red = urealloc((char *)cp->lookup.red, nalloc);
            cp->lookup.grn = urealloc((char *)cp->lookup.grn, nalloc);
            cp->lookup.blu = urealloc((char *)cp->lookup.blu, nalloc);
            cp->lookup.set = urealloc((char *)cp->lookup.set, nalloc);
        }

        /* shift the table to make room in front */
        for (i = 1; i <= curlen; i++) {
            cp->lookup.red[newlen - i] = cp->lookup.red[curlen - i];
            cp->lookup.grn[newlen - i] = cp->lookup.grn[curlen - i];
            cp->lookup.blu[newlen - i] = cp->lookup.blu[curlen - i];
            cp->lookup.set[newlen - i] = cp->lookup.set[curlen - i];
        }

        /* fill in gap with white */
        for (i = 1; i < gap; i++) {
            cp->lookup.red[i] = 255;
            cp->lookup.grn[i] = 255;
            cp->lookup.blu[i] = 255;
            cp->lookup.set[i] = 0;
        }
        cp->min = cat;
    }

    /* set the color! */
    i = cat - cp->min;
    cp->lookup.red[i] = red;
    cp->lookup.grn[i] = grn;
    cp->lookup.blu[i] = blu;
    cp->lookup.set[i] = 1;

    return 1;
}