PostGIS  3.4.0dev-r@@SVN_REVISION@@

◆ gserialized2_from_lwgeom()

GSERIALIZED* gserialized2_from_lwgeom ( LWGEOM geom,
size_t *  size 
)

Allocate a new GSERIALIZED from an LWGEOM.

For all non-point types, a bounding box will be calculated and embedded in the serialization. The geodetic flag is used to control the box calculation (cartesian or geocentric). If set, the size pointer will contain the size of the final output, which is useful for setting the PgSQL VARSIZE information.

Definition at line 1146 of file gserialized2.c.

1147 {
1148  size_t expected_size = 0;
1149  size_t return_size = 0;
1150  uint8_t *ptr = NULL;
1151  GSERIALIZED *g = NULL;
1152  assert(geom);
1153 
1154  /*
1155  ** See if we need a bounding box, add one if we don't have one.
1156  */
1157  if ((!geom->bbox) && lwgeom_needs_bbox(geom) && (!lwgeom_is_empty(geom)))
1158  {
1159  lwgeom_add_bbox(geom);
1160  }
1161 
1162  /*
1163  ** Harmonize the flags to the state of the lwgeom
1164  */
1165  FLAGS_SET_BBOX(geom->flags, (geom->bbox ? 1 : 0));
1166 
1167  /* Set up the uint8_t buffer into which we are going to write the serialized geometry. */
1168  expected_size = gserialized2_from_lwgeom_size(geom);
1169  ptr = lwalloc(expected_size);
1170  g = (GSERIALIZED*)(ptr);
1171 
1172  /* Set the SRID! */
1173  gserialized2_set_srid(g, geom->srid);
1174  /*
1175  ** We are aping PgSQL code here, PostGIS code should use
1176  ** VARSIZE to set this for real.
1177  */
1178  LWSIZE_SET(g->size, expected_size);
1179  g->gflags = lwflags_get_g2flags(geom->flags);
1180 
1181  /* Move write head past size, srid and flags. */
1182  ptr += 8;
1183 
1184  /* Write in the extended flags if necessary */
1185  ptr += gserialized2_from_extended_flags(geom->flags, ptr);
1186 
1187  /* Write in the serialized form of the gbox, if necessary. */
1188  if (geom->bbox)
1189  ptr += gserialized2_from_gbox(geom->bbox, ptr);
1190 
1191  /* Write in the serialized form of the geometry. */
1192  ptr += gserialized2_from_lwgeom_any(geom, ptr);
1193 
1194  /* Calculate size as returned by data processing functions. */
1195  return_size = ptr - (uint8_t*)g;
1196 
1197  assert(expected_size == return_size);
1198  if (size) /* Return the output size to the caller if necessary. */
1199  *size = return_size;
1200 
1201  return g;
1202 }
void gserialized2_set_srid(GSERIALIZED *g, int32_t srid)
Write the SRID into the serialized form (it is packed into three bytes so this is a handy function).
Definition: gserialized2.c:208
static size_t gserialized2_from_gbox(const GBOX *gbox, uint8_t *buf)
uint8_t lwflags_get_g2flags(lwflags_t lwflags)
Definition: gserialized2.c:118
static size_t gserialized2_from_lwgeom_any(const LWGEOM *geom, uint8_t *buf)
size_t gserialized2_from_lwgeom_size(const LWGEOM *geom)
Return the memory size a GSERIALIZED will occupy for a given LWGEOM.
Definition: gserialized2.c:776
static size_t gserialized2_from_extended_flags(lwflags_t lwflags, uint8_t *buf)
#define FLAGS_SET_BBOX(flags, value)
Definition: liblwgeom.h:174
int lwgeom_needs_bbox(const LWGEOM *geom)
Check whether or not a lwgeom is big enough to warrant a bounding box.
Definition: lwgeom.c:1208
#define LWSIZE_SET(varsize, len)
Definition: liblwgeom.h:325
void * lwalloc(size_t size)
Definition: lwutil.c:227
void lwgeom_add_bbox(LWGEOM *lwgeom)
Compute a bbox if not already computed.
Definition: lwgeom.c:695
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
uint32_t size
Definition: liblwgeom.h:444
uint8_t gflags
Definition: liblwgeom.h:446
GBOX * bbox
Definition: liblwgeom.h:458
int32_t srid
Definition: liblwgeom.h:460
lwflags_t flags
Definition: liblwgeom.h:461

References LWGEOM::bbox, LWGEOM::flags, FLAGS_SET_BBOX, GSERIALIZED::gflags, gserialized2_from_extended_flags(), gserialized2_from_gbox(), gserialized2_from_lwgeom_any(), gserialized2_from_lwgeom_size(), gserialized2_set_srid(), lwalloc(), lwflags_get_g2flags(), lwgeom_add_bbox(), lwgeom_is_empty(), lwgeom_needs_bbox(), LWSIZE_SET, GSERIALIZED::size, and LWGEOM::srid.

Referenced by gserialized_from_lwgeom(), peek2_point_helper(), test_gserialized2_extended_flags(), test_gserialized2_is_empty(), test_gserialized2_peek_gbox_p_gets_correct_box(), test_gserialized2_peek_gbox_p_no_box_when_empty(), test_lwgeom_from_gserialized2(), and test_on_gser2_lwgeom_count_vertices().

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