transform()

Datum transform

(

PG_FUNCTION_ARGS

)

Definition at line 51 of file postgis/lwgeom_transform.c.

{
        GSERIALIZED* geom;
        GSERIALIZED* result=NULL;
        LWGEOM* lwgeom;
        LWPROJ *pj;
        int32 srid_to, srid_from;
 
        srid_to = PG_GETARG_INT32(1);
        if (srid_to == SRID_UNKNOWN)
        {
                elog(ERROR, "ST_Transform: %d is an invalid target SRID", SRID_UNKNOWN);
                PG_RETURN_NULL();
        }
 
        geom = PG_GETARG_GSERIALIZED_P_COPY(0);
        srid_from = gserialized_get_srid(geom);
 
        if ( srid_from == SRID_UNKNOWN )
        {
                PG_FREE_IF_COPY(geom, 0);
                elog(ERROR, "ST_Transform: Input geometry has unknown (%d) SRID", SRID_UNKNOWN);
                PG_RETURN_NULL();
        }
 
        /* Input SRID and output SRID are equal, noop */
        if ( srid_from == srid_to )
                PG_RETURN_POINTER(geom);
 
        postgis_initialize_cache();
        if ( lwproj_lookup(srid_from, srid_to, &pj) == LW_FAILURE )
        {
                PG_FREE_IF_COPY(geom, 0);
                elog(ERROR, "ST_Transform: Failure reading projections from spatial_ref_sys.");
                PG_RETURN_NULL();
        }
 
        /* now we have a geometry, and input/output PJ structs. */
        lwgeom = lwgeom_from_gserialized(geom);
        lwgeom_transform(lwgeom, pj);
        lwgeom->srid = srid_to;
 
        /* Re-compute bbox if input had one (COMPUTE_BBOX TAINTING) */
        if ( lwgeom->bbox )
        {
                lwgeom_refresh_bbox(lwgeom);
        }
 
        result = geometry_serialize(lwgeom);
        lwgeom_free(lwgeom);
        PG_FREE_IF_COPY(geom, 0);
 
        PG_RETURN_POINTER(result); /* new geometry */
}

References LWGEOM::bbox, gserialized_get_srid(), LW_FAILURE, lwgeom_free(), lwgeom_from_gserialized(), lwgeom_refresh_bbox(), lwgeom_transform(), result, LWGEOM::srid, and SRID_UNKNOWN.

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