PostGIS  2.5.1dev-r@@SVN_REVISION@@

◆ LWGEOM_envelope()

Datum LWGEOM_envelope ( PG_FUNCTION_ARGS  )

Definition at line 1703 of file lwgeom_functions_basic.c.

References dumpnode::geom, geometry_serialize(), LW_FAILURE, LW_TRUE, lwalloc(), lwgeom_calculate_gbox(), lwgeom_from_gserialized(), lwgeom_is_empty(), LWGEOM_isempty(), lwline_as_lwgeom(), lwline_construct(), lwline_free(), lwpoint_as_lwgeom(), lwpoint_free(), lwpoint_make2d(), lwpoly_as_lwgeom(), lwpoly_construct(), lwpoly_free(), PG_FUNCTION_INFO_V1(), ptarray_append_point(), ptarray_construct_empty(), LWGEOM::srid, POINT4D::x, GBOX::xmax, GBOX::xmin, POINT4D::y, GBOX::ymax, and GBOX::ymin.

Referenced by LWGEOM_to_BOX().

1704 {
1705  GSERIALIZED *geom = PG_GETARG_GSERIALIZED_P(0);
1706  LWGEOM *lwgeom = lwgeom_from_gserialized(geom);
1707  int srid = lwgeom->srid;
1708  POINT4D pt;
1709  GBOX box;
1710  POINTARRAY *pa;
1711  GSERIALIZED *result;
1712 
1713 
1714  if ( lwgeom_is_empty(lwgeom) )
1715  {
1716  /* must be the EMPTY geometry */
1717  PG_RETURN_POINTER(geom);
1718  }
1719 
1720  if ( lwgeom_calculate_gbox(lwgeom, &box) == LW_FAILURE )
1721  {
1722  /* must be the EMPTY geometry */
1723  PG_RETURN_POINTER(geom);
1724  }
1725 
1726  /*
1727  * Alter envelope type so that a valid geometry is always
1728  * returned depending upon the size of the geometry. The
1729  * code makes the following assumptions:
1730  * - If the bounding box is a single point then return a
1731  * POINT geometry
1732  * - If the bounding box represents either a horizontal or
1733  * vertical line, return a LINESTRING geometry
1734  * - Otherwise return a POLYGON
1735  */
1736 
1737  if ( (box.xmin == box.xmax) && (box.ymin == box.ymax) )
1738  {
1739  /* Construct and serialize point */
1740  LWPOINT *point = lwpoint_make2d(srid, box.xmin, box.ymin);
1741  result = geometry_serialize(lwpoint_as_lwgeom(point));
1742  lwpoint_free(point);
1743  }
1744  else if ( (box.xmin == box.xmax) || (box.ymin == box.ymax) )
1745  {
1746  LWLINE *line;
1747  /* Construct point array */
1748  pa = ptarray_construct_empty(0, 0, 2);
1749 
1750  /* Assign coordinates to POINT2D array */
1751  pt.x = box.xmin;
1752  pt.y = box.ymin;
1753  ptarray_append_point(pa, &pt, LW_TRUE);
1754  pt.x = box.xmax;
1755  pt.y = box.ymax;
1756  ptarray_append_point(pa, &pt, LW_TRUE);
1757 
1758  /* Construct and serialize linestring */
1759  line = lwline_construct(srid, NULL, pa);
1760  result = geometry_serialize(lwline_as_lwgeom(line));
1761  lwline_free(line);
1762  }
1763  else
1764  {
1765  LWPOLY *poly;
1766  POINTARRAY **ppa = lwalloc(sizeof(POINTARRAY*));
1767  pa = ptarray_construct_empty(0, 0, 5);
1768  ppa[0] = pa;
1769 
1770  /* Assign coordinates to POINT2D array */
1771  pt.x = box.xmin;
1772  pt.y = box.ymin;
1773  ptarray_append_point(pa, &pt, LW_TRUE);
1774  pt.x = box.xmin;
1775  pt.y = box.ymax;
1776  ptarray_append_point(pa, &pt, LW_TRUE);
1777  pt.x = box.xmax;
1778  pt.y = box.ymax;
1779  ptarray_append_point(pa, &pt, LW_TRUE);
1780  pt.x = box.xmax;
1781  pt.y = box.ymin;
1782  ptarray_append_point(pa, &pt, LW_TRUE);
1783  pt.x = box.xmin;
1784  pt.y = box.ymin;
1785  ptarray_append_point(pa, &pt, LW_TRUE);
1786 
1787  /* Construct polygon */
1788  poly = lwpoly_construct(srid, NULL, 1, ppa);
1789  result = geometry_serialize(lwpoly_as_lwgeom(poly));
1790  lwpoly_free(poly);
1791  }
1792 
1793  PG_FREE_IF_COPY(geom, 0);
1794 
1795  PG_RETURN_POINTER(result);
1796 }
double x
Definition: liblwgeom.h:354
LWGEOM * lwgeom_from_gserialized(const GSERIALIZED *g)
Allocate a new LWGEOM from a GSERIALIZED.
LWPOINT * lwpoint_make2d(int srid, double x, double y)
Definition: lwpoint.c:163
double xmax
Definition: liblwgeom.h:295
POINTARRAY * ptarray_construct_empty(char hasz, char hasm, uint32_t maxpoints)
Create a new POINTARRAY with no points.
Definition: ptarray.c:70
void lwpoint_free(LWPOINT *pt)
Definition: lwpoint.c:213
void lwline_free(LWLINE *line)
Definition: lwline.c:76
int32_t srid
Definition: liblwgeom.h:401
LWGEOM * lwpoly_as_lwgeom(const LWPOLY *obj)
Definition: lwgeom.c:320
#define LW_FAILURE
Definition: liblwgeom.h:78
int lwgeom_calculate_gbox(const LWGEOM *lwgeom, GBOX *gbox)
Calculate bounding box of a geometry, automatically taking into account whether it is cartesian or ge...
Definition: lwgeom.c:746
double ymin
Definition: liblwgeom.h:296
LWGEOM * geom
LWGEOM * lwline_as_lwgeom(const LWLINE *obj)
Definition: lwgeom.c:330
double xmin
Definition: liblwgeom.h:294
int ptarray_append_point(POINTARRAY *pa, const POINT4D *pt, int allow_duplicates)
Append a point to the end of an existing POINTARRAY If allow_duplicate is LW_FALSE, then a duplicate point will not be added.
Definition: ptarray.c:156
LWPOLY * lwpoly_construct(int srid, GBOX *bbox, uint32_t nrings, POINTARRAY **points)
Definition: lwpoly.c:43
void lwpoly_free(LWPOLY *poly)
Definition: lwpoly.c:175
#define LW_TRUE
Return types for functions with status returns.
Definition: liblwgeom.h:75
LWLINE * lwline_construct(int srid, GBOX *bbox, POINTARRAY *points)
Definition: lwline.c:42
double ymax
Definition: liblwgeom.h:297
GSERIALIZED * geometry_serialize(LWGEOM *lwgeom)
LWGEOM * lwpoint_as_lwgeom(const LWPOINT *obj)
Definition: lwgeom.c:335
void * lwalloc(size_t size)
Definition: lwutil.c:229
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:1393
double y
Definition: liblwgeom.h:354
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