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#3050 Peak into header for GeometryType

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git-svn-id: http://svn.osgeo.org/postgis/trunk@13253 b70326c6-7e19-0410-871a-916f4a2858ee
This commit is contained in:
Paul Ramsey 2015-02-20 18:22:33 +00:00
parent 18a9eb4e41
commit 72679d9daa
3 changed files with 28 additions and 18 deletions
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6
liblwgeom/g_serialized.c
View file

@ -42,6 +42,12 @@ int gserialized_ndims(const GSERIALIZED *gser)
return FLAGS_NDIMS(gser->flags);
}
uint32_t gserialized_max_header_size()
{
/* read GSERIALIZED size + max bbox according gbox_serialized_size (2 + Z + M) + 1 int for type */
return sizeof(GSERIALIZED) + 8 * sizeof(float) + sizeof(int);
}
uint32_t gserialized_get_type(const GSERIALIZED *s)
{
uint32_t *ptr;

6
liblwgeom/liblwgeom.h.in
View file

@ -656,6 +656,12 @@ extern uint8_t gflags(int hasz, int hasm, int geodetic);
*/
extern uint32_t gserialized_get_type(const GSERIALIZED *g);
/**
* Returns the size in bytes to read from toast to get the basic
* information from a geometry: GSERIALIZED struct, bbox and type
*/
extern uint32_t gserialized_max_header_size();
/**
* Extract the SRID from the serialized form (it is packed into
* three bytes so this is a handy function).

34
postgis/lwgeom_ogc.c
View file

@ -107,19 +107,17 @@ Datum LWGEOM_set_srid(PG_FUNCTION_ARGS)
PG_FUNCTION_INFO_V1(LWGEOM_getTYPE);
Datum LWGEOM_getTYPE(PG_FUNCTION_ARGS)
{
GSERIALIZED *lwgeom;
char *text_ob;
GSERIALIZED *gser;
text *text_ob;
char *result;
int32 size;
uint8_t type;
static int maxtyplen = 20;
lwgeom = (GSERIALIZED *)PG_DETOAST_DATUM(PG_GETARG_DATUM(0));
text_ob = lwalloc(20+VARHDRSZ);
result = text_ob+VARHDRSZ;
gser = (GSERIALIZED*)PG_DETOAST_DATUM_SLICE(PG_GETARG_DATUM(0), 0, gserialized_max_header_size());
text_ob = palloc0(VARHDRSZ + maxtyplen);
result = VARDATA(text_ob);
type = gserialized_get_type(lwgeom);
memset(VARDATA(text_ob), 0, 20);
type = gserialized_get_type(gser);
if (type == POINTTYPE)
strcpy(result,"POINT");
@ -154,15 +152,14 @@ Datum LWGEOM_getTYPE(PG_FUNCTION_ARGS)
else
strcpy(result,"UNKNOWN");
if ( gserialized_has_m(lwgeom) && ! gserialized_has_z(lwgeom) )
if ( gserialized_has_m(gser) && ! gserialized_has_z(gser) )
strcat(result, "M");
size = strlen(result) + VARHDRSZ ;
SET_VARSIZE(text_ob, size); /* size of string */
SET_VARSIZE(text_ob, strlen(result) + VARHDRSZ); /* size of string */
PG_FREE_IF_COPY(lwgeom, 0);
PG_FREE_IF_COPY(gser, 0);
PG_RETURN_POINTER(text_ob);
PG_RETURN_TEXT_P(text_ob);
}
@ -170,24 +167,25 @@ Datum LWGEOM_getTYPE(PG_FUNCTION_ARGS)
PG_FUNCTION_INFO_V1(geometry_geometrytype);
Datum geometry_geometrytype(PG_FUNCTION_ARGS)
{
GSERIALIZED *lwgeom;
GSERIALIZED *gser;
text *type_text;
char *type_str = palloc(32);
lwgeom = (GSERIALIZED*)PG_DETOAST_DATUM(PG_GETARG_DATUM(0));
/* Read just the header from the toasted tuple */
gser = (GSERIALIZED*)PG_DETOAST_DATUM_SLICE(PG_GETARG_DATUM(0), 0, gserialized_max_header_size());
/* Make it empty string to start */
*type_str = 0;
/* Build up the output string */
strncat(type_str, "ST_", 32);
strncat(type_str, lwtype_name(gserialized_get_type(lwgeom)), 32);
strncat(type_str, lwtype_name(gserialized_get_type(gser)), 32);
/* Build a text type to store things in */
type_text = cstring2text(type_str);
pfree(type_str);
PG_FREE_IF_COPY(lwgeom, 0);
PG_FREE_IF_COPY(gser, 0);
PG_RETURN_TEXT_P(type_text);
}