geography_centroid()

Datum geography_centroid

(

PG_FUNCTION_ARGS

)

Definition at line 53 of file geography_centroid.c.

{
        LWGEOM *lwgeom = NULL;
        LWGEOM *lwgeom_out = NULL;
    LWPOINT *lwpoint_out = NULL;
        GSERIALIZED *g = NULL;
        GSERIALIZED *g_out = NULL;
        int32_t srid;
        bool use_spheroid = true;
        SPHEROID s;
 
        /* Get our geometry object loaded into memory. */
        g = PG_GETARG_GSERIALIZED_P(0);
        lwgeom = lwgeom_from_gserialized(g);
 
        if (g == NULL)
        {
                PG_RETURN_NULL();
        }
 
        srid = lwgeom_get_srid(lwgeom);
 
        /* on empty input, return empty output */
        if (gserialized_is_empty(g))
        {
                LWCOLLECTION* empty = lwcollection_construct_empty(COLLECTIONTYPE, srid, 0, 0);
                lwgeom_out = lwcollection_as_lwgeom(empty);
                g_out = geography_serialize(lwgeom_out);
                PG_RETURN_POINTER(g_out);
        }
 
    /* Initialize spheroid */
    spheroid_init_from_srid(srid, &s);
 
    /* Set to sphere if requested */
    use_spheroid = PG_GETARG_BOOL(1);
        if ( ! use_spheroid )
                s.a = s.b = s.radius;
 
        switch (lwgeom_get_type(lwgeom))
        {
 
        case POINTTYPE:
    {
        /* centroid of a point is itself */
        PG_RETURN_POINTER(g);
        break;
    }
 
        case MULTIPOINTTYPE:
    {
        LWMPOINT* mpoints = lwgeom_as_lwmpoint(lwgeom);
 
        /* average between all points */
        uint32_t size = mpoints->ngeoms;
        POINT3DM* points = palloc(size*sizeof(POINT3DM));
 
                uint32_t i;
                for (i = 0; i < size; i++) {
            points[i].x = lwpoint_get_x(mpoints->geoms[i]);
            points[i].y = lwpoint_get_y(mpoints->geoms[i]);
            points[i].m = 1;
        }
 
                lwpoint_out = geography_centroid_from_wpoints(srid, points, size);
        pfree(points);
        break;
    }
 
        case LINETYPE:
    {
        LWLINE* line = lwgeom_as_lwline(lwgeom);
 
        /* reuse mline function */
        LWMLINE* mline = lwmline_construct_empty(srid, 0, 0);
        lwmline_add_lwline(mline, line);
 
        lwpoint_out = geography_centroid_from_mline(mline, &s);
        lwmline_free(mline);
                break;
    }
 
        case MULTILINETYPE:
    {
        LWMLINE* mline = lwgeom_as_lwmline(lwgeom);
        lwpoint_out = geography_centroid_from_mline(mline, &s);
                break;
    }
 
        case POLYGONTYPE:
    {
        LWPOLY* poly = lwgeom_as_lwpoly(lwgeom);
 
        /* reuse mpoly function */
        LWMPOLY* mpoly = lwmpoly_construct_empty(srid, 0, 0);
        lwmpoly_add_lwpoly(mpoly, poly);
 
        lwpoint_out = geography_centroid_from_mpoly(mpoly, use_spheroid, &s);
        lwmpoly_free(mpoly);
        break;
    }
 
        case MULTIPOLYGONTYPE:
    {
        LWMPOLY* mpoly = lwgeom_as_lwmpoly(lwgeom);
        lwpoint_out = geography_centroid_from_mpoly(mpoly, use_spheroid, &s);
        break;
    }
        default:
                elog(ERROR, "ST_Centroid(geography) unhandled geography type");
                PG_RETURN_NULL();
        }
 
        PG_FREE_IF_COPY(g, 0);
 
    lwgeom_out = lwpoint_as_lwgeom(lwpoint_out);
    g_out = geography_serialize(lwgeom_out);
 
        PG_RETURN_POINTER(g_out);
}

References COLLECTIONTYPE, geography_centroid_from_mline(), geography_centroid_from_mpoly(), geography_centroid_from_wpoints(), LWMPOINT::geoms, gserialized_is_empty(), LINETYPE, lwcollection_as_lwgeom(), lwcollection_construct_empty(), lwgeom_as_lwline(), lwgeom_as_lwmline(), lwgeom_as_lwmpoint(), lwgeom_as_lwmpoly(), lwgeom_as_lwpoly(), lwgeom_from_gserialized(), lwgeom_get_srid(), lwgeom_get_type(), lwmline_add_lwline(), lwmline_construct_empty(), lwmline_free(), lwmpoly_add_lwpoly(), lwmpoly_construct_empty(), lwmpoly_free(), lwpoint_as_lwgeom(), lwpoint_get_x(), lwpoint_get_y(), POINT3DM::m, MULTILINETYPE, MULTIPOINTTYPE, MULTIPOLYGONTYPE, LWMPOINT::ngeoms, POINTTYPE, POLYGONTYPE, s, POINT3DM::x, and POINT3DM::y.

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