mirror of
https://git.osgeo.org/gitea/postgis/postgis
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Made asText and asBinary strict OGC conformant, introduced asEWKT and asEWKB
for extended version outputs. git-svn-id: http://svn.osgeo.org/postgis/trunk@1175 b70326c6-7e19-0410-871a-916f4a2858ee
This commit is contained in:
Sandro Santilli
parent
c02b57d287
commit
5f59c5f1ec
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@ -696,19 +696,53 @@ AND
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<sect1 id="RefObject">
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<title>GIS Objects</title>
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<para>The GIS objects supported by PostGIS are the "Simple Features"
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defined by the OpenGIS Consortium (OGC). As of version 0.9, PostGIS
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supports all the objects and functions specified in the OGC "Simple
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<para>The GIS objects supported by PostGIS are a superset of
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the "Simple Features" defined by the OpenGIS Consortium (OGC).
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As of version 0.9, PostGIS supports all the objects and functions
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specified in the OGC "Simple
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Features for SQL" specification.</para>
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<para>Examples of the text representations of the spatial objects of the
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features are as follows:</para>
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<para>Examples of the text representations (WKT) of the spatial
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objects of the features are as follows:</para>
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<itemizedlist>
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<listitem>
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<para>POINT(0 0) -- XY</para>
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<para>POINT(0 0)</para>
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</listitem>
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<listitem>
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<para>LINESTRING(0 0,1 1,1 2)</para>
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</listitem>
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<listitem>
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<para>POLYGON((0 0,4 0,4 4,0 4,0 0),(1 1, 2 1, 2 2, 1 2,1 1))</para>
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</listitem>
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<listitem>
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<para>MULTIPOINT(0 0,1 2)</para>
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</listitem>
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<listitem>
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<para>MULTILINESTRING((0 0,1 1,1 2),(2 3,3 2,5 4))</para>
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</listitem>
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<listitem>
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<para>MULTIPOLYGON(((0 0,4 0,4 4,0 4,0 0),(1 1,2 1,2 2,1 2,1 1)),
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((-1 -1,-1 -2,-2 -2,-2 -1,-1 -1)))</para>
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</listitem>
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<listitem>
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<para>GEOMETRYCOLLECTION(POINT(2 3),LINESTRING((2 3,3 4)))</para>
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</listitem>
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</itemizedlist>
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<para>PostGIS extends the standard with support for 3DZ,3DM and 4D
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coordinates. Examples of the text representations (EWKT) of the
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extended spatial objects of the features are as follows:</para>
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<itemizedlist>
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<listitem>
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<para>POINT(0 0 0) -- XYZ</para>
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</listitem>
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@ -722,16 +756,7 @@ AND
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</listitem>
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<listitem>
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<para>LINESTRING(0 0,1 1,1 2)</para>
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</listitem>
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<listitem>
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<para>POLYGON((0 0 0,4 0 0,4 4 0,0 4 0,0 0 0),(1 1 0,2 1 0,2 2 0,1 2
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0,1 1 0))</para>
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</listitem>
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<listitem>
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<para>MULTIPOINT(0 0 0,1 2 1)</para>
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<para>MULTIPOINTM(0 0 0,1 2 1)</para>
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</listitem>
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<listitem>
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@ -739,28 +764,23 @@ AND
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1))</para>
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</listitem>
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<listitem>
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<para>POLYGON((0 0 0,4 0 0,4 4 0,0 4 0,0 0 0),(1 1 0,2 1 0,2 2 0,1 2
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0,1 1 0))</para>
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</listitem>
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<listitem>
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<para>MULTIPOLYGON(((0 0 0,4 0 0,4 4 0,0 4 0,0 0 0),(1 1 0,2 1 0,2 2
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0,1 2 0,1 1 0)),((-1 -1 0,-1 -2 0,-2 -2 0,-2 -1 0,-1 -1 0)))</para>
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</listitem>
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<listitem>
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<para>GEOMETRYCOLLECTION(POINT(2 3 9),LINESTRING((2 3 4,3 4
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<para>GEOMETRYCOLLECTIONM(POINT(2 3 9),LINESTRING((2 3 4,3 4
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5)))</para>
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</listitem>
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</itemizedlist>
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<para>Note that in the examples above there are features with
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2-dimensional, 3-dimensional (XYZ,XYM) and 4-dimensional coordinates.
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PostGIS supports 2D,3DZ,3DM and 4D coordinates -- if you describe a
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feature with 2D coordinates when you insert it, the database will
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return that feature to you with 2D coordinates when you extract it.
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See the sections on the <link linkend="force_2d">force_2d()</link>,
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<link linkend="force_3dz">force_3dz()</link>,
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<link linkend="force_3dm">force_3dm()</link> and
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<link linkend="force_4d">force_4d()</link> functions for information
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on converting features to a particular coordinate dimension
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representation.</para>
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<sect2>
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<title>Standard versus Canonical Forms</title>
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@ -793,23 +813,24 @@ VALUES (
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<para>The "canonical form" of the spatial objects in PostgreSQL is a
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text representation which includes all the information necessary to
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construct the object. Unlike the OpenGIS standard forms, it includes
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the type, coordinate, <emphasis>and</emphasis> SRID information. The
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canonical form is the default form returned from a SELECT query.
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Since version 1.0.0 the canonical form is an HEX-encoded WKB with
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an optional SRID=#; prefix.
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the type, dimensions, coordinate, <emphasis>and</emphasis> SRID
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information. The canonical form is the default form returned from a
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SELECT query.
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Since version 1.0.0 the canonical form is an HEX-encoded extended
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WKB (EWKB).
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The example below shows the difference between the OGC standard and
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PostGIS canonical forms:</para>
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<programlisting>db=> SELECT AsText(geom) AS OGCGeom FROM SPATIALTABLE;
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OGCGeom
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-------------------------------------------------
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POINT(-126.4 45.32)
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POINT(-126.4 45.32)
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(1 row)
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db=> SELECT geom AS PostGISGeom FROM thetable;
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PostGISGeom
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-------------------------------------------------
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SRID=312;01010000009A99999999995FC0295C8FC2F5A84640
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0101000020380100009A99999999995FC0295C8FC2F5A84640
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(1 row)</programlisting>
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</sect2>
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</sect1>
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@ -3934,7 +3955,7 @@ FROM geometry_table;</literallayout>
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<variablelist>
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<varlistentry>
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<term>asbinary(geometry,'NDR')</term>
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<term>asBinary(geometry,'NDR')</term>
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<listitem>
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<para>Returns the geometry in the OGC "well-known-binary" format,
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@ -3945,7 +3966,7 @@ FROM geometry_table;</literallayout>
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</varlistentry>
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<varlistentry>
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<term>asbinary(geometry,'XDR')</term>
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<term>asBinary(geometry,'XDR')</term>
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<listitem>
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<para>Returns the geometry in the OGC "well-known-binary" format,
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@ -28,12 +28,6 @@ Datum LWGEOM_length2d_linestring(PG_FUNCTION_ARGS);
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Datum LWGEOM_length_linestring(PG_FUNCTION_ARGS);
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Datum LWGEOM_perimeter2d_poly(PG_FUNCTION_ARGS);
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Datum LWGEOM_perimeter_poly(PG_FUNCTION_ARGS);
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Datum LWGEOM_force_2d(PG_FUNCTION_ARGS);
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Datum LWGEOM_force_3dm(PG_FUNCTION_ARGS);
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Datum LWGEOM_force_3dz(PG_FUNCTION_ARGS);
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Datum LWGEOM_force_4d(PG_FUNCTION_ARGS);
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Datum LWGEOM_force_collection(PG_FUNCTION_ARGS);
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Datum LWGEOM_force_multi(PG_FUNCTION_ARGS);
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Datum LWGEOM_mindistance2d(PG_FUNCTION_ARGS);
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Datum LWGEOM_maxdistance2d_linestring(PG_FUNCTION_ARGS);
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Datum LWGEOM_translate(PG_FUNCTION_ARGS);
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@ -2547,3 +2541,36 @@ Datum LWGEOM_addpoint(PG_FUNCTION_ARGS)
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PG_RETURN_POINTER(result);
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}
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//convert LWGEOM to wwkt (in TEXT format)
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PG_FUNCTION_INFO_V1(LWGEOM_asEWKT);
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Datum LWGEOM_asEWKT(PG_FUNCTION_ARGS)
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{
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PG_LWGEOM *lwgeom;
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PG_LWGEOM *ogclwgeom;
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char *result_cstring;
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int len;
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char *result,*loc_wkt;
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//char *semicolonLoc;
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init_pg_func();
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lwgeom = (PG_LWGEOM *)PG_DETOAST_DATUM(PG_GETARG_DATUM(0));
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result_cstring = unparse_WKT(SERIALIZED_FORM(lwgeom),lwalloc,lwfree);
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//semicolonLoc = strchr(result_cstring,';');
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////loc points to start of wkt
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//if (semicolonLoc == NULL) loc_wkt = result_cstring;
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//else loc_wkt = semicolonLoc +1;
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loc_wkt = result_cstring;
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len = strlen(loc_wkt)+4;
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result = palloc(len);
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memcpy(result, &len, 4);
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memcpy(result+4,loc_wkt, len-4);
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pfree(result_cstring);
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PG_RETURN_POINTER(result);
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}
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@ -31,10 +31,6 @@
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void elog_ERROR(const char* string);
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// needed for OGC conformance
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Datum LWGEOMFromWKB(PG_FUNCTION_ARGS);
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Datum WKBFromLWGEOM(PG_FUNCTION_ARGS);
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Datum LWGEOM_in(PG_FUNCTION_ARGS);
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Datum LWGEOM_out(PG_FUNCTION_ARGS);
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Datum LWGEOM_addBBOX(PG_FUNCTION_ARGS);
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@ -55,6 +55,8 @@ Datum LWGEOM_startpoint_linestring(PG_FUNCTION_ARGS);
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Datum LWGEOM_endpoint_linestring(PG_FUNCTION_ARGS);
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// ---- AsText(geometry)
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Datum LWGEOM_asText(PG_FUNCTION_ARGS);
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// ---- AsBinary(geometry, [XDR|NDR])
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Datum LWGEOM_asBinary(PG_FUNCTION_ARGS);
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// ---- GeometryFromText(text, integer)
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Datum LWGEOM_from_text(PG_FUNCTION_ARGS);
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// ---- IsClosed(geometry)
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@ -733,22 +735,27 @@ PG_FUNCTION_INFO_V1(LWGEOM_asText);
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Datum LWGEOM_asText(PG_FUNCTION_ARGS)
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{
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PG_LWGEOM *lwgeom;
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PG_LWGEOM *ogclwgeom;
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char *result_cstring;
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int len;
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char *result,*loc_wkt;
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//char *semicolonLoc;
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char *semicolonLoc;
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init_pg_func();
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lwgeom = (PG_LWGEOM *)PG_DETOAST_DATUM(PG_GETARG_DATUM(0));
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result_cstring = unparse_WKT(SERIALIZED_FORM(lwgeom),lwalloc,lwfree);
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//semicolonLoc = strchr(result_cstring,';');
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/* Force to 2d */
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ogclwgeom = (PG_LWGEOM *)DatumGetPointer(DirectFunctionCall1(
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LWGEOM_force_2d, PointerGetDatum(lwgeom)));
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////loc points to start of wkt
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//if (semicolonLoc == NULL) loc_wkt = result_cstring;
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//else loc_wkt = semicolonLoc +1;
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loc_wkt = result_cstring;
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result_cstring = unparse_WKT(SERIALIZED_FORM(ogclwgeom),lwalloc,lwfree);
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semicolonLoc = strchr(result_cstring,';');
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//loc points to start of wkt
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if (semicolonLoc == NULL) loc_wkt = result_cstring;
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else loc_wkt = semicolonLoc +1;
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len = strlen(loc_wkt)+4;
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result = palloc(len);
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@ -760,6 +767,39 @@ Datum LWGEOM_asText(PG_FUNCTION_ARGS)
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PG_RETURN_POINTER(result);
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}
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//convert LWGEOM to wkb (in BINARY format)
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PG_FUNCTION_INFO_V1(LWGEOM_asBinary);
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Datum LWGEOM_asBinary(PG_FUNCTION_ARGS)
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{
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PG_LWGEOM *ogclwgeom;
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char *result;
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init_pg_func();
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/* Force to 2d */
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ogclwgeom = (PG_LWGEOM *)DatumGetPointer(DirectFunctionCall1(
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LWGEOM_force_2d, PG_GETARG_DATUM(0)));
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/* Drop SRID */
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ogclwgeom = (PG_LWGEOM *)DatumGetPointer(DirectFunctionCall2(
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LWGEOM_setSRID, PointerGetDatum(ogclwgeom), -1));
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/* Call WKBFromLWGEOM */
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if ( (PG_NARGS()>1) && (!PG_ARGISNULL(1)) )
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{
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result = (char *)DatumGetPointer(DirectFunctionCall2(
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WKBFromLWGEOM, PointerGetDatum(ogclwgeom),
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PG_GETARG_DATUM(1)));
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}
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else
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{
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result = (char *)DatumGetPointer(DirectFunctionCall1(
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WKBFromLWGEOM, PointerGetDatum(ogclwgeom)));
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}
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PG_RETURN_POINTER(result);
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}
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char line_is_closed(LWLINE *line)
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{
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POINT4D *sp, *ep;
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@ -43,5 +43,15 @@ Datum LWGEOM_same(PG_FUNCTION_ARGS);
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Datum BOX3D_construct(PG_FUNCTION_ARGS);
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Datum BOX2DFLOAT4_ymin(PG_FUNCTION_ARGS);
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Datum LWGEOM_force_2d(PG_FUNCTION_ARGS);
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Datum LWGEOM_force_3dm(PG_FUNCTION_ARGS);
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Datum LWGEOM_force_3dz(PG_FUNCTION_ARGS);
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Datum LWGEOM_force_4d(PG_FUNCTION_ARGS);
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Datum LWGEOM_force_collection(PG_FUNCTION_ARGS);
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Datum LWGEOM_force_multi(PG_FUNCTION_ARGS);
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Datum LWGEOMFromWKB(PG_FUNCTION_ARGS);
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Datum WKBFromLWGEOM(PG_FUNCTION_ARGS);
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#endif // !defined _LWGEOM_PG_H 1
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@ -1119,12 +1119,12 @@ CREATEFUNCTION SetSRID(geometry,int4)
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CREATEFUNCTION AsBinary(geometry)
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RETURNS bytea
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AS '@MODULE_FILENAME@','WKBFromLWGEOM'
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AS '@MODULE_FILENAME@','LWGEOM_asBinary'
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LANGUAGE 'C' WITH (isstrict,iscachable);
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CREATEFUNCTION AsBinary(geometry,text)
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RETURNS bytea
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AS '@MODULE_FILENAME@','WKBFromLWGEOM'
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AS '@MODULE_FILENAME@','LWGEOM_asBinary'
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LANGUAGE 'C' WITH (isstrict,iscachable);
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CREATEFUNCTION AsText(geometry)
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@ -1703,6 +1703,21 @@ CREATEFUNCTION ndims(geometry)
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AS '@MODULE_FILENAME@', 'LWGEOM_ndims'
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LANGUAGE 'C' WITH (iscachable,isstrict);
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CREATEFUNCTION AsEWKT(geometry)
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RETURNS TEXT
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AS '@MODULE_FILENAME@','LWGEOM_asEWKT'
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LANGUAGE 'C' WITH (isstrict,iscachable);
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CREATEFUNCTION AsEWKB(geometry)
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RETURNS BYTEA
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AS '@MODULE_FILENAME@','WKBFromLWGEOM'
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LANGUAGE 'C' WITH (isstrict,iscachable);
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CREATEFUNCTION AsEWKB(geometry,text)
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RETURNS bytea
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AS '@MODULE_FILENAME@','WKBFromLWGEOM'
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LANGUAGE 'C' WITH (isstrict,iscachable);
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------------------------------------------------------------------------
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-- CONSTRUCTORS
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------------------------------------------------------------------------
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