PostGIS  3.1.6dev-r@@SVN_REVISION@@

◆ geography_length()

Datum geography_length ( PG_FUNCTION_ARGS  )

Definition at line 627 of file geography_measurement.c.

628 {
629  LWGEOM *lwgeom = NULL;
630  GSERIALIZED *g = NULL;
631  double length;
632  bool use_spheroid = LW_TRUE;
633  SPHEROID s;
634 
635  /* Get our geometry object loaded into memory. */
636  g = PG_GETARG_GSERIALIZED_P(0);
637  lwgeom = lwgeom_from_gserialized(g);
638 
639  /* EMPTY things have no length */
640  if ( lwgeom_is_empty(lwgeom) || lwgeom->type == POLYGONTYPE || lwgeom->type == MULTIPOLYGONTYPE )
641  {
642  lwgeom_free(lwgeom);
643  PG_RETURN_FLOAT8(0.0);
644  }
645 
646  /* Read our calculation type */
647  use_spheroid = PG_GETARG_BOOL(1);
648 
649  /* Initialize spheroid */
650  spheroid_init_from_srid(gserialized_get_srid(g), &s);
651 
652  /* User requests spherical calculation, turn our spheroid into a sphere */
653  if ( ! use_spheroid )
654  s.a = s.b = s.radius;
655 
656  /* Calculate the length */
657  length = lwgeom_length_spheroid(lwgeom, &s);
658 
659  /* Something went wrong... */
660  if ( length < 0.0 )
661  {
662  elog(ERROR, "lwgeom_length_spheroid returned length < 0.0");
663  PG_RETURN_NULL();
664  }
665 
666  /* Clean up */
667  lwgeom_free(lwgeom);
668 
669  PG_FREE_IF_COPY(g, 0);
670  PG_RETURN_FLOAT8(length);
671 }
char * s
Definition: cu_in_wkt.c:23
int32_t gserialized_get_srid(const GSERIALIZED *g)
Extract the SRID from the serialized form (it is packed into three bytes so this is a handy function)...
Definition: gserialized.c:126
LWGEOM * lwgeom_from_gserialized(const GSERIALIZED *g)
Allocate a new LWGEOM from a GSERIALIZED.
Definition: gserialized.c:239
void lwgeom_free(LWGEOM *geom)
Definition: lwgeom.c:1138
#define MULTIPOLYGONTYPE
Definition: liblwgeom.h:121
#define POLYGONTYPE
Definition: liblwgeom.h:118
double lwgeom_length_spheroid(const LWGEOM *geom, const SPHEROID *s)
Calculate the geodetic length of a lwgeom on the unit sphere.
Definition: lwgeodetic.c:3287
#define LW_TRUE
Return types for functions with status returns.
Definition: liblwgeom.h:107
static int lwgeom_is_empty(const LWGEOM *geom)
Return true or false depending on whether a geometry is an "empty" geometry (no vertices members)
Definition: lwinline.h:203
uint8_t type
Definition: liblwgeom.h:476

References gserialized_get_srid(), LW_TRUE, lwgeom_free(), lwgeom_from_gserialized(), lwgeom_is_empty(), lwgeom_length_spheroid(), MULTIPOLYGONTYPE, POLYGONTYPE, s, and LWGEOM::type.

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