TWKBFromLWGEOM()

Datum TWKBFromLWGEOM

(

PG_FUNCTION_ARGS

)

Definition at line 473 of file lwgeom_inout.c.

{
        GSERIALIZED *geom;
        LWGEOM *lwgeom;
        uint8_t *twkb;
        size_t twkb_size;
        uint8_t variant = 0;
        bytea *result;
        srs_precision sp;
 
        /*check for null input since we cannot have the sql-function as strict.
        That is because we use null as default for optional ID*/
        if ( PG_ARGISNULL(0) ) PG_RETURN_NULL();
 
        geom = PG_GETARG_GSERIALIZED_P(0);
 
        /* Read sensible precision defaults (about one meter) given the srs */
        sp = srid_axis_precision(fcinfo, gserialized_get_srid(geom), TWKB_DEFAULT_PRECISION);
 
        /* If user specified XY precision, use it */
        if ( PG_NARGS() > 1 && ! PG_ARGISNULL(1) )
                sp.precision_xy = PG_GETARG_INT32(1);
 
        /* If user specified Z precision, use it */
        if ( PG_NARGS() > 2 && ! PG_ARGISNULL(2) )
                sp.precision_z = PG_GETARG_INT32(2);
 
        /* If user specified M precision, use it */
        if ( PG_NARGS() > 3 && ! PG_ARGISNULL(3) )
                sp.precision_m = PG_GETARG_INT32(3);
 
        /* We don't permit ids for single geoemtries */
        variant = variant & ~TWKB_ID;
 
        /* If user wants registered twkb sizes */
        if ( PG_NARGS() > 4 && ! PG_ARGISNULL(4) && PG_GETARG_BOOL(4) )
                variant |= TWKB_SIZE;
 
        /* If user wants bounding boxes */
        if ( PG_NARGS() > 5 && ! PG_ARGISNULL(5) && PG_GETARG_BOOL(5) )
                variant |= TWKB_BBOX;
 
        /* Create TWKB binary string */
        lwgeom = lwgeom_from_gserialized(geom);
        twkb = lwgeom_to_twkb(lwgeom, variant, sp.precision_xy, sp.precision_z, sp.precision_m, &twkb_size);
 
        /* Prepare the PgSQL text return type */
        result = palloc(twkb_size + VARHDRSZ);
        memcpy(VARDATA(result), twkb, twkb_size);
        SET_VARSIZE(result, twkb_size + VARHDRSZ);
 
        PG_RETURN_BYTEA_P(result);
}

References gserialized_get_srid(), lwgeom_from_gserialized(), lwgeom_to_twkb(), TWKB_BBOX, TWKB_DEFAULT_PRECISION, TWKB_SIZE, and variant.

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