PostGIS  2.3.8dev-r@@SVN_REVISION@@

◆ lwpoint_from_wkb_state()

static LWPOINT* lwpoint_from_wkb_state ( wkb_parse_state s)
static

POINT Read a WKB point, starting just after the endian byte, type number and optional srid number.

Advance the parse state forward appropriately. WKB point has just a set of doubles, with the quantity depending on the dimension of the point, so this looks like a special case of the above with only one point.

Definition at line 388 of file lwin_wkb.c.

References double_from_wkb_state(), getPoint2d_cp(), wkb_parse_state::has_m, wkb_parse_state::has_z, lwpoint_construct(), lwpoint_construct_empty(), wkb_parse_state::pos, ptarray_construct(), ptarray_construct_copy_data(), ptarray_free(), POINTARRAY::serialized_pointlist, wkb_parse_state::srid, wkb_parse_state::swap_bytes, WKB_DOUBLE_SIZE, wkb_parse_state_check(), POINT2D::x, and POINT2D::y.

Referenced by lwgeom_from_wkb_state().

389 {
390  static uint32_t npoints = 1;
391  POINTARRAY *pa = NULL;
392  size_t pa_size;
393  uint32_t ndims = 2;
394  const POINT2D *pt;
395 
396  /* Count the dimensions. */
397  if( s->has_z ) ndims++;
398  if( s->has_m ) ndims++;
399  pa_size = ndims * WKB_DOUBLE_SIZE;
400 
401  /* Does the data we want to read exist? */
402  wkb_parse_state_check(s, pa_size);
403 
404  /* If we're in a native endianness, we can just copy the data directly! */
405  if( ! s->swap_bytes )
406  {
407  pa = ptarray_construct_copy_data(s->has_z, s->has_m, npoints, (uint8_t*)s->pos);
408  s->pos += pa_size;
409  }
410  /* Otherwise we have to read each double, separately */
411  else
412  {
413  int i = 0;
414  double *dlist;
415  pa = ptarray_construct(s->has_z, s->has_m, npoints);
416  dlist = (double*)(pa->serialized_pointlist);
417  for( i = 0; i < ndims; i++ )
418  {
419  dlist[i] = double_from_wkb_state(s);
420  }
421  }
422 
423  /* Check for POINT(NaN NaN) ==> POINT EMPTY */
424  pt = getPoint2d_cp(pa, 0);
425  if ( isnan(pt->x) && isnan(pt->y) )
426  {
427  ptarray_free(pa);
428  return lwpoint_construct_empty(s->srid, s->has_z, s->has_m);
429  }
430  else
431  {
432  return lwpoint_construct(s->srid, NULL, pa);
433  }
434 }
POINTARRAY * ptarray_construct(char hasz, char hasm, uint32_t npoints)
Construct an empty pointarray, allocating storage and setting the npoints, but not filling in any inf...
Definition: ptarray.c:62
uint8_t * serialized_pointlist
Definition: liblwgeom.h:365
void ptarray_free(POINTARRAY *pa)
Definition: ptarray.c:330
#define WKB_DOUBLE_SIZE
Well-Known Binary (WKB) Output Variant Types.
LWPOINT * lwpoint_construct_empty(int srid, char hasz, char hasm)
Definition: lwpoint.c:133
double x
Definition: liblwgeom.h:327
const POINT2D * getPoint2d_cp(const POINTARRAY *pa, int n)
Returns a POINT2D pointer into the POINTARRAY serialized_ptlist, suitable for reading from...
Definition: lwgeom_api.c:485
POINTARRAY * ptarray_construct_copy_data(char hasz, char hasm, uint32_t npoints, const uint8_t *ptlist)
Construct a new POINTARRAY, copying in the data from ptlist.
Definition: ptarray.c:309
static void wkb_parse_state_check(wkb_parse_state *s, size_t next)
Check that we are not about to read off the end of the WKB array.
Definition: lwin_wkb.c:125
double y
Definition: liblwgeom.h:327
uint32_t srid
Definition: lwin_wkb.c:42
LWPOINT * lwpoint_construct(int srid, GBOX *bbox, POINTARRAY *point)
Definition: lwpoint.c:111
static double double_from_wkb_state(wkb_parse_state *s)
Double Read an 8-byte double and advance the parse state forward.
Definition: lwin_wkb.c:297
const uint8_t * pos
Definition: lwin_wkb.c:46
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