PostGIS  2.1.10dev-r@@SVN_REVISION@@
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 1057 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 buildarea1(), buildarea2(), buildarea3(), buildarea4(), buildarea4b(), buildarea5(), buildarea6(), buildarea7(), and ST_BuildArea().

1058 {
1059  GEOSGeometry* geos_in;
1060  GEOSGeometry* geos_out;
1061  LWGEOM* geom_out;
1062  int SRID = (int)(geom->srid);
1063  int is3d = FLAGS_GET_Z(geom->flags);
1064 
1065  /* Can't build an area from an empty! */
1066  if ( lwgeom_is_empty(geom) )
1067  {
1068  return (LWGEOM*)lwpoly_construct_empty(SRID, is3d, 0);
1069  }
1070 
1071  LWDEBUG(3, "buildarea called");
1072 
1073  LWDEBUGF(3, "ST_BuildArea got geom @ %p", geom);
1074 
1075  initGEOS(lwnotice, lwgeom_geos_error);
1076 
1077  geos_in = LWGEOM2GEOS(geom);
1078 
1079  if ( 0 == geos_in ) /* exception thrown at construction */
1080  {
1081  lwerror("First argument geometry could not be converted to GEOS: %s", lwgeom_geos_errmsg);
1082  return NULL;
1083  }
1084  geos_out = LWGEOM_GEOS_buildArea(geos_in);
1085  GEOSGeom_destroy(geos_in);
1086 
1087  if ( ! geos_out ) /* exception thrown.. */
1088  {
1089  lwerror("LWGEOM_GEOS_buildArea: %s", lwgeom_geos_errmsg);
1090  return NULL;
1091  }
1092 
1093  /* If no geometries are in result collection, return NULL */
1094  if ( GEOSGetNumGeometries(geos_out) == 0 )
1095  {
1096  GEOSGeom_destroy(geos_out);
1097  return NULL;
1098  }
1099 
1100  geom_out = GEOS2LWGEOM(geos_out, is3d);
1101  GEOSGeom_destroy(geos_out);
1102 
1103 #if PARANOIA_LEVEL > 0
1104  if ( geom_out == NULL )
1105  {
1106  lwerror("serialization error");
1107  return NULL;
1108  }
1109 
1110 #endif
1111 
1112  return geom_out;
1113 }
uint8_t flags
Definition: liblwgeom.h:353
char lwgeom_geos_errmsg[LWGEOM_GEOS_ERRMSG_MAXSIZE]
#define LWDEBUG(level, msg)
Definition: lwgeom_log.h:50
GEOSGeometry * LWGEOM2GEOS(const LWGEOM *lwgeom)
int32_t srid
Definition: liblwgeom.h:355
void lwerror(const char *fmt,...)
Write a notice out to the error handler.
Definition: lwutil.c:67
void lwnotice(const char *fmt,...)
Write a notice out to the notice handler.
Definition: lwutil.c:54
void lwgeom_geos_error(const char *fmt,...)
#define FLAGS_GET_Z(flags)
Macros for manipulating the 'flags' byte.
Definition: liblwgeom.h:106
LWPOLY * lwpoly_construct_empty(int srid, char hasz, char hasm)
Definition: lwpoly.c:66
LWGEOM * GEOS2LWGEOM(const GEOSGeometry *geom, char want3d)
int lwgeom_is_empty(const LWGEOM *geom)
Return true or false depending on whether a geometry is an "empty" geometry (no vertices members) ...
Definition: lwgeom.c:1229
#define LWDEBUGF(level, msg,...)
Definition: lwgeom_log.h:55
GEOSGeometry * LWGEOM_GEOS_buildArea(const GEOSGeometry *geom_in)

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