lwpoly_from_wkb_state()

static LWPOLY * lwpoly_from_wkb_state ( wkb_parse_state *  s )

static

POLYGON Read a WKB polygon, starting just after the endian byte, type number and optional srid number.

Advance the parse state forward appropriately. First read the number of rings, then read each ring (which are structured as point arrays)

Definition at line 529 of file lwin_wkb.c.

{
        uint32_t nrings = integer_from_wkb_state(s);
        if (s->error)
                return NULL;
        uint32_t i = 0;
        LWPOLY *poly = lwpoly_construct_empty(s->srid, s->has_z, s->has_m);
 
        LWDEBUGF(4,"Polygon has %d rings", nrings);
 
        /* Empty polygon? */
        if( nrings == 0 )
                return poly;
 
        for( i = 0; i < nrings; i++ )
        {
                POINTARRAY *pa = ptarray_from_wkb_state(s);
                if (pa == NULL)
                {
                        lwpoly_free(poly);
                        return NULL;
                }
 
                /* Check for at least four points. */
                if (s->check & LW_PARSER_CHECK_MINPOINTS && pa->npoints < 4)
                {
                        lwpoly_free(poly);
                        LWDEBUGF(2, "%s must have at least four points in each ring", lwtype_name(s->lwtype));
                        lwerror("%s must have at least four points in each ring", lwtype_name(s->lwtype));
                        return NULL;
                }
 
                /* Check that first and last points are the same. */
                if( s->check & LW_PARSER_CHECK_CLOSURE && ! ptarray_is_closed_2d(pa) )
                {
                        lwpoly_free(poly);
                        LWDEBUGF(2, "%s must have closed rings", lwtype_name(s->lwtype));
                        lwerror("%s must have closed rings", lwtype_name(s->lwtype));
                        return NULL;
                }
 
                /* Skip zero-member rings, they add nothing */
                if ( pa->npoints == 0)
                {
                        LWDEBUGF(2, "Skipping empty ring [%d]", i);
                        ptarray_free(pa);
                        continue;
                }
 
                /* Add ring to polygon */
                if ( lwpoly_add_ring(poly, pa) == LW_FAILURE )
                {
                        lwpoly_free(poly);
                        LWDEBUG(2, "Unable to add ring to polygon");
                        lwerror("Unable to add ring to polygon");
                        return NULL;
                }
 
        }
        return poly;
}

References integer_from_wkb_state(), LW_FAILURE, LW_PARSER_CHECK_CLOSURE, LW_PARSER_CHECK_MINPOINTS, LWDEBUG, LWDEBUGF, lwerror(), lwpoly_add_ring(), lwpoly_construct_empty(), lwpoly_free(), lwtype_name(), POINTARRAY::npoints, ptarray_free(), ptarray_from_wkb_state(), ptarray_is_closed_2d(), and s.

Referenced by lwgeom_from_wkb_state().

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