lwgeom_buildarea()

LWGEOM* lwgeom_buildarea

(

const LWGEOM *

geom

)

Take a geometry and return an areal geometry (Polygon or MultiPolygon).

Actually a wrapper around GEOSpolygonize, transforming the resulting collection into a valid polygon Geometry.

Definition at line 1411 of file liblwgeom/lwgeom_geos.c.

References LWGEOM::flags, FLAGS_GET_Z, GEOS2LWGEOM(), LWDEBUG, LWDEBUGF, lwerror(), LWGEOM2GEOS(), LWGEOM_GEOS_buildArea(), lwgeom_geos_errmsg, lwgeom_geos_error(), lwgeom_is_empty(), lwnotice(), lwpoly_construct_empty(), and LWGEOM::srid.

Referenced by _lwt_FaceByEdges(), buildarea1(), buildarea2(), buildarea3(), buildarea4(), buildarea4b(), buildarea5(), buildarea6(), buildarea7(), and ST_BuildArea().

{
        GEOSGeometry* geos_in;
        GEOSGeometry* geos_out;
        LWGEOM* geom_out;
        int SRID = (int)(geom->srid);
        int is3d = FLAGS_GET_Z(geom->flags);

        /* Can't build an area from an empty! */
        if ( lwgeom_is_empty(geom) )
        {
                return (LWGEOM*)lwpoly_construct_empty(SRID, is3d, 0);
        }

        LWDEBUG(3, "buildarea called");

        LWDEBUGF(3, "ST_BuildArea got geom @ %p", geom);

        initGEOS(lwnotice, lwgeom_geos_error);

        geos_in = LWGEOM2GEOS(geom, 0);

        if ( 0 == geos_in )   /* exception thrown at construction */
        {
                lwerror("First argument geometry could not be converted to GEOS: %s", lwgeom_geos_errmsg);
                return NULL;
        }
        geos_out = LWGEOM_GEOS_buildArea(geos_in);
        GEOSGeom_destroy(geos_in);

        if ( ! geos_out ) /* exception thrown.. */
        {
                lwerror("LWGEOM_GEOS_buildArea: %s", lwgeom_geos_errmsg);
                return NULL;
        }

        /* If no geometries are in result collection, return NULL */
        if ( GEOSGetNumGeometries(geos_out) == 0 )
        {
                GEOSGeom_destroy(geos_out);
                return NULL;
        }

        geom_out = GEOS2LWGEOM(geos_out, is3d);
        GEOSGeom_destroy(geos_out);

#if PARANOIA_LEVEL > 0
        if ( geom_out == NULL )
        {
                lwerror("%s [%s] serialization error", __FILE__, __LINE__);
                return NULL;
        }

#endif

        return geom_out;
}

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