color_look.c

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/*!
 * \file lib/raster/color_look.c
 *
 * \brief Raster Library - Lookup array of colors
 *
 * SPDX-FileCopyrightText: 1999-2009 GRASS Development Team
 * SPDX-License-Identifier: GPL-2.0-or-later
 *
 * \author USACERL and many others
 */
 
#include <math.h>
 
#include <grass/gis.h>
#include <grass/raster.h>
 
/*!
 * \brief Lookup an array of colors
 *
 * Extracts colors for an array of <i>cell</i> values. The colors
 * for the <i>n</i> values in the <i>cell</i> array are stored in
 * the <i>red, green</i>, and <i>blue</i> arrays. The values in the
 * <i>set</i> array will indicate if the corresponding <i>cell</i>
 * value has a color or not (1 means it does, 0 means it does not).
 *
 * The programmer must allocate the <i>red, green, blue</i>, and
 * <b>set</b> arrays to be at least dimension <i>n</i>.
 *
 * <b>Note:</b> The <i>red, green</i>, and <i>blue</i> intensities
 * will be in the range 0 - 255.
 *
 * Modified to return a color for NULL-values.
 *
 * \param cell raster cell value
 * \param[out] red red value
 * \param[out] grn green value
 * \param[out] blu blue value
 * \param set array which indicates if color is set or not
 * \param n number of values
 * \param colors pointer to Colors structure which holds color info
 */
void Rast_lookup_c_colors(const CELL *cell, unsigned char *red,
                          unsigned char *grn, unsigned char *blu,
                          unsigned char *set, int n, struct Colors *colors)
{
    Rast__organize_colors(
        colors); /* make sure the lookup tables are in place */
 
    G_zero((char *)set, n * sizeof(unsigned char));
 
    /* first lookup the fixed colors */
    Rast__lookup_colors((void *)cell, red, grn, blu, set, n, colors, 0, 0,
                        CELL_TYPE);
 
    /* now lookup unset colors using the modular rules */
    Rast__lookup_colors((void *)cell, red, grn, blu, set, n, colors, 1, 0,
                        CELL_TYPE);
}
 
/*!
 * \brief Lookup an array of colors
 *
 * - If the <em>map_type</em> is CELL_TYPE, calls Rast_lookup_colors()
 * - If the <em>map_type</em> is FCELL_TYPE, calls Rast_lookup_f_colors()
 * - If the <em>map_type</em> is DCELL_TYPE, calls Rast_lookup_d_colors()
 *
 * \param raster raster cell value
 * \param[out] red red value
 * \param[out] grn green value
 * \param[out] blu blue value
 * \param set array which indicates if color is set or not
 * \param n number of values
 * \param colors pointer to Colors structure which holds color info
 * \param map_type raster type (CELL, FCELL, DCELL)
 */
void Rast_lookup_colors(const void *raster, unsigned char *red,
                        unsigned char *grn, unsigned char *blu,
                        unsigned char *set, int n, struct Colors *colors,
                        RASTER_MAP_TYPE map_type)
{
    Rast__organize_colors(
        colors); /* make sure the lookup tables are in place */
    /* in case of float color rules, fp_lookup table is created */
 
    G_zero((char *)set, n * sizeof(unsigned char));
 
    /* first lookup the fixed colors */
    Rast__lookup_colors(raster, red, grn, blu, set, n, colors, 0, 0, map_type);
 
    /* now lookup unset colors using the modular rules */
    Rast__lookup_colors(raster, red, grn, blu, set, n, colors, 1, 0, map_type);
}
 
/*!
 * \brief Lookup an array of colors (FCELL)
 *
 * Converts the <em>n</em> floating-point values in the <em>fcell</em>
 * array to their <em>r,g,b</em> color components. Embedded
 * NULL-values are handled properly as well.
 *
 * \param fcell raster cell value
 * \param[out] red red value
 * \param[out] grn green value
 * \param[out] blu blue value
 * \param set array which indicates if color is set or not
 * \param n number of values
 * \param colors pointer to Colors structure which holds color info
 */
void Rast_lookup_f_colors(const FCELL *fcell, unsigned char *red,
                          unsigned char *grn, unsigned char *blu,
                          unsigned char *set, int n, struct Colors *colors)
{
    Rast__organize_colors(
        colors); /* make sure the lookup tables are in place */
    /* in case of float color rules, fp_lookup table is created */
 
    G_zero((char *)set, n * sizeof(unsigned char));
 
    /* first lookup the fixed colors */
    Rast__lookup_colors((void *)fcell, red, grn, blu, set, n, colors, 0, 0,
                        FCELL_TYPE);
 
    /* now lookup unset colors using the modular rules */
    Rast__lookup_colors((void *)fcell, red, grn, blu, set, n, colors, 1, 0,
                        FCELL_TYPE);
}
 
/*!
 * \brief Lookup an array of colors (DCELL)
 *
 * Converts the <em>n</em> double-precision values in the
 * <em>dcell</em> array to their <em>r,g,b</em> color
 * components. Embedded NULL-values are handled properly as well.
 *
 * \param dcell raster cell value
 * \param[out] red red value
 * \param[out] grn green value
 * \param[out] blu blue value
 * \param set array which indicates if color is set or not
 * \param n number of values
 * \param colors pointer to Colors structure which holds color info
 */
void Rast_lookup_d_colors(const DCELL *dcell, unsigned char *red,
                          unsigned char *grn, unsigned char *blu,
                          unsigned char *set, int n, struct Colors *colors)
{
    Rast__organize_colors(
        colors); /* make sure the lookup tables are in place */
    /* in case of float color rules, fp_lookup table is created */
 
    G_zero((char *)set, n * sizeof(unsigned char));
 
    /* first lookup the fixed colors */
    Rast__lookup_colors((void *)dcell, red, grn, blu, set, n, colors, 0, 0,
                        DCELL_TYPE);
 
    /* now lookup unset colors using the modular rules */
    Rast__lookup_colors((void *)dcell, red, grn, blu, set, n, colors, 1, 0,
                        DCELL_TYPE);
}
 
static int less_or_equal(double x, double y)
{
    if (x <= y)
        return 1;
    else
        return 0;
}
 
static int less(double x, double y)
{
    if (x < y)
        return 1;
    else
        return 0;
}
 
/*!
 * \brief Lookup an array of colors
 *
 * \param raster raster cell value
 * \param[out] red red value
 * \param[out] grn green value
 * \param[out] blu blue value
 * \param set array which indicates if color is set or not
 * \param n number of values
 * \param colors pointer to Colors structure which holds color info
 * \param mod
 * \param rules_only
 * \param data_type raster type (CELL, FCELL, DCELL)
 */
void Rast__lookup_colors(const void *raster, unsigned char *red,
                         unsigned char *grn, unsigned char *blu,
                         unsigned char *set, int n, struct Colors *colors,
                         int mod, int rules_only, RASTER_MAP_TYPE data_type)
{
    struct _Color_Info_ *cp;
    struct _Color_Rule_ *rule;
    DCELL dmin, dmax, val, dmod = 0L, shift;
    CELL cat, min, max;
    const void *ptr, *last_ptr = NULL;
    int invert;
    int found, r, g, b;
    int cell_type;
    int lookup, max_ind, min_ind, try;
    int (*lower)(double, double);
    size_t size = Rast_cell_size(data_type);
 
    if (mod)
        cp = &colors->modular;
    else
        cp = &colors->fixed;
 
    /* rules_only will be true only when called by Rast__organize_colors()
     * when building the integer lookup talbes from the rules,
     * so do not shift, invert, use lookup table or modulate cats.
     * these operations will happen when lookup is called by user code
     */
    /* we want min, max for cp, not min, max overall */
    dmin = cp->min;
    dmax = cp->max;
    min = (CELL)dmin;
    max = (CELL)dmax;
 
    cell_type = (data_type == CELL_TYPE);
 
    if (rules_only) {
        shift = invert = lookup = mod = 0;
    }
    else {
        if (mod) {
            dmod = dmax - dmin;
            /* for integers color table we make a gap of 1 in order
               to make the same colors as before */
            if (cell_type)
                dmod += 1;
        }
 
        shift = colors->shift;
        invert = colors->invert;
        lookup = cp->lookup.active;
    }
 
    ptr = raster;
 
    for (; n-- > 0; ptr = G_incr_void_ptr(ptr, size), red++, grn++, blu++,
                    *set++ = found) {
        /* if the cell is the same as last one, use the prev color values */
        if (ptr != raster && Rast_raster_cmp(ptr, last_ptr, data_type) == 0) {
            *red = *(red - 1);
            *blu = *(blu - 1);
            *grn = *(grn - 1);
            found = *(set - 1);
            last_ptr = ptr;
            continue;
        }
        val = Rast_get_d_value(ptr, data_type);
        /* DEBUG fprintf (stderr, "val: %.4lf\n", val); */
        last_ptr = ptr;
 
        if (*set) {
            found = 1;
            continue;
        }
 
        if (Rast_is_null_value(ptr, data_type)) {
            /* returns integers, not unsigned chars */
            Rast_get_null_value_color(&r, &g, &b, colors);
            *red = r;
            *grn = g;
            *blu = b;
            found = 1;
            continue;
        }
 
        if (shift && val >= dmin && val <= dmax) {
            val += shift;
            while (val < dmin)
                val += dmax - dmin + 1;
            while (val > dmax)
                val -= dmax - dmin + 1;
        }
 
        /* invert non-null data around midpoint of range [min:max] */
        if (invert)
            val = dmin + dmax - val;
 
        if (mod) {
            if (dmod > 0) {
                val -= dmin;
                while (val < 0)
                    val += dmod;
                val = val - dmod * floor(val / dmod);
                val += dmin;
            }
            else
                val = dmin;
        }
 
        cat = (CELL)val;
 
        found = 0;
 
        /* for non-null integers  try to look them up in lookup table */
        /* note: lookup table exists only for integer maps, and we also must
           check if val is really integer */
 
        if (lookup && ((double)cat - val == 0.)) {
            if (cat >= min && cat <= max) {
                cat -= min;
                if (cp->lookup.set[cat]) {
                    *red = cp->lookup.red[cat];
                    *grn = cp->lookup.grn[cat];
                    *blu = cp->lookup.blu[cat];
                    found = 1;
                    /*DEBUG
                       fprintf (stderr, "lookup %d %.2lf %d %d %d\n\n", cat,
                       val, *red, *grn, *blu);
                     */
                }
            }
        }
 
        if (found)
            continue;
 
        /* if floating point lookup table is active, look up in there */
        if (cp->fp_lookup.active) {
            try = (cp->fp_lookup.nalloc - 1) / 2;
            min_ind = 0;
            max_ind = cp->fp_lookup.nalloc - 2;
            while (1) {
                /* when the rule for the interval is NULL, we exclude the end
                   points. when it exists, we include the end-points */
                if (cp->fp_lookup.rules[try])
                    lower = less;
                else
                    lower = less_or_equal;
                /* DEBUG
                   fprintf (stderr, "%d %d %d %lf %lf %lf\n", min_ind, try,
                   max_ind, cp->fp_lookup.vals[try-1], val,
                   cp->fp_lookup.vals[try]);
                 */
 
                if (lower(cp->fp_lookup.vals[try + 1],
                          val)) { /* recurse to the second half */
                    min_ind = try + 1;
                    /* must be still < nalloc-1, since number is within the
                     * range */
                    try = (max_ind + min_ind) / 2;
                    if (min_ind > max_ind) {
                        rule = NULL;
                        break;
                    }
                    continue;
                }
                if (lower(val, cp->fp_lookup.vals[try])) { /* recurse to the
                                                              second half */
                    max_ind = try - 1;
                    /* must be still >= 0, since number is within the range */
                    try = (max_ind + min_ind) / 2;
                    if (max_ind < min_ind) {
                        rule = NULL;
                        break;
                    }
                    continue;
                }
                rule = cp->fp_lookup.rules[try];
                break;
            }
        }
        else {
            /* find the [low:high] rule that applies */
            for (rule = cp->rules; rule; rule = rule->next) {
                /* DEBUG
                   fprintf (stderr, "%.2lf %.2lf %.2lf\n",
                   val, rule->low.value, rule->high.value);
                 */
                if (rule->low.value <= val && val <= rule->high.value)
                    break;
            }
        }
 
        /* if found, perform linear interpolation from low to high.
         * else set colors to colors->undef or white if undef not set
         */
 
        if (rule) {
            Rast__interpolate_color_rule(val, red, grn, blu, rule);
            found = 1;
        }
        if (!found) {
            /* otherwise use default color */
            Rast_get_default_color(&r, &g, &b, colors);
            *red = r;
            *grn = g;
            *blu = b;
        }
        /* DEBUG
           if (rule)
           fprintf (stderr, "%.2lf %d %d %d   %.2lf %d %d %d \n",
           rule->low.value , (int)rule->low.red, (int)rule->low.grn,
           (int)rule->low.blu, rule->high.value, (int)rule->high.red,
           (int)rule->high.grn, (int)rule->high.blu); fprintf (stderr, "rule
           found %d %.2lf %d %d %d\n\n", cat, val, *red, *grn, *blu);
         */
    }
}
 
/*!
   \brief Interpolate color rules
 
   \param val raster cell value
   \param[out] red red value
   \param[out] grn green value
   \param[out] blu blue value
   \param rule pointer to _Color_Rule which holds color rules info
 */
void Rast__interpolate_color_rule(DCELL val, unsigned char *red,
                                  unsigned char *grn, unsigned char *blu,
                                  const struct _Color_Rule_ *rule)
{
    DCELL delta;
 
    if ((delta = rule->high.value - rule->low.value)) {
        val -= rule->low.value;
 
        *red = (int)(val * (double)((int)rule->high.red - (int)rule->low.red) /
                     delta) +
               (int)rule->low.red;
        *grn = (int)(val * (double)((int)rule->high.grn - (int)rule->low.grn) /
                     delta) +
               (int)rule->low.grn;
        *blu = (int)(val * (double)((int)rule->high.blu - (int)rule->low.blu) /
                     delta) +
               (int)rule->low.blu;
    }
    else {
        *red = rule->low.red;
        *grn = rule->low.grn;
        *blu = rule->low.blu;
    }
}