rt_band_get_pixel_of_value()

int rt_band_get_pixel_of_value	(	rt_band	band,
		int	exclude_nodata_value,
		double *	searchset,
		int	searchcount,
		rt_pixel *	pixels
	)

Search band for pixel(s) with search values.

Parameters

band	: the band to query for minimum and maximum pixel values
exclude_nodata_value	: if non-zero, ignore nodata values
searchset	: array of values to count
searchcount	: the number of search values
pixels	: pixels with the search value

Returns

-1 on error, otherwise number of pixels

Definition at line 1989 of file rt_band.c.

  {
        int x;
        int y;
        int i;
        double pixval;
        int err;
        int count = 0;
        int isnodata = 0;
        int isequal = 0;
 
        rt_pixel pixel = NULL;
 
        assert(NULL != band);
        assert(NULL != pixels);
        assert(NULL != searchset && searchcount > 0);
 
        if (!band->hasnodata)
                exclude_nodata_value = FALSE;
        /* band is NODATA and exclude_nodata_value = TRUE, nothing to search */
        else if (exclude_nodata_value && band->isnodata) {
                RASTER_DEBUG(4, "Pixels cannot be searched as band is NODATA and excluding NODATA values");
                return 0;
        }
 
        for (x = 0; x < band->width; x++) {
                for (y = 0; y < band->height; y++) {
                        err = rt_band_get_pixel(band, x, y, &pixval, &isnodata);
                        if (err != ES_NONE) {
                                rterror("rt_band_get_pixel_of_value: Cannot get band pixel");
                                return -1;
                        }
                        else if (exclude_nodata_value && isnodata)
                                continue;
 
                        for (i = 0; i < searchcount; i++) {
                                if (rt_pixtype_compare_clamped_values(band->pixtype, searchset[i], pixval, &isequal) != ES_NONE) {
                                        continue;
                                }
 
                                if (FLT_NEQ(pixval, searchset[i]) || !isequal)
                                        continue;
 
                                /* match found */
                                count++;
                                if (*pixels == NULL)
                                        *pixels = (rt_pixel) rtalloc(sizeof(struct rt_pixel_t) * count);
                                else
                                        *pixels = (rt_pixel) rtrealloc(*pixels, sizeof(struct rt_pixel_t) * count);
                                if (*pixels == NULL) {
                                        rterror("rt_band_get_pixel_of_value: Could not allocate memory for pixel(s)");
                                        return -1;
                                }
 
                                pixel = &((*pixels)[count - 1]);
                                pixel->x = x;
                                pixel->y = y;
                                pixel->nodata = 0;
                                pixel->value = pixval;
                        }
                }
        }
 
        return count;
}

References ES_NONE, FALSE, FLT_NEQ, RASTER_DEBUG, rt_band_get_pixel(), rt_pixtype_compare_clamped_values(), rtalloc(), rterror(), and rtrealloc().

Referenced by RASTER_pixelOfValue(), and test_band_get_pixel_of_value().

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