From: Paul Ramsey <pramsey@cleverelephant.ca>
Date: Fri, 17 Jun 2011 21:11:05 +0000 (+0000)
Subject: Define alias ST_Perimeter (for geography ST_Length) (#526)
X-Git-Tag: 2.0.0alpha1~1412
X-Git-Url: https://granicus.if.org/sourcecode?a=commitdiff_plain;h=ade9d75792b340ea1eab0fe94a3f09253b3910a9;p=postgis

Define alias ST_Perimeter (for geography ST_Length) (#526)


git-svn-id: http://svn.osgeo.org/postgis/trunk@7414 b70326c6-7e19-0410-871a-916f4a2858ee
---

diff --git a/postgis/geography.sql.in.c b/postgis/geography.sql.in.c
index b860a5c4b..2b1431c65 100644
--- a/postgis/geography.sql.in.c
+++ b/postgis/geography.sql.in.c
@@ -658,6 +658,21 @@ CREATE OR REPLACE FUNCTION ST_Length(text)
 	$$ SELECT ST_Length($1::geometry);  $$
 	LANGUAGE 'SQL' IMMUTABLE STRICT;
 
+
+-- Availability: 2.0.0
+CREATE OR REPLACE FUNCTION ST_Perimeter(geography, boolean)
+	RETURNS float8
+	AS 'MODULE_PATHNAME','geography_perimeter'
+	LANGUAGE 'C' IMMUTABLE STRICT
+	COST 100;
+
+-- Availability: 2.0.0
+CREATE OR REPLACE FUNCTION ST_Perimeter(geography)
+	RETURNS float8
+	AS 'SELECT ST_Perimeter($1, true)'
+	LANGUAGE 'SQL' IMMUTABLE;
+
+
 -- Availability: 1.5.0
 CREATE OR REPLACE FUNCTION _ST_PointOutside(geography)
 	RETURNS geography
diff --git a/postgis/geography_measurement.c b/postgis/geography_measurement.c
index 30b5bd86c..9ea6d2bae 100644
--- a/postgis/geography_measurement.c
+++ b/postgis/geography_measurement.c
@@ -268,9 +268,68 @@ Datum geography_area(PG_FUNCTION_ARGS)
 
 }
 
+/*
+** geography_perimeter(GSERIALIZED *g)
+** returns double perimeter in meters for area features
+*/
+PG_FUNCTION_INFO_V1(geography_perimeter);
+Datum geography_perimeter(PG_FUNCTION_ARGS)
+{
+	LWGEOM *lwgeom = NULL;
+	GSERIALIZED *g = NULL;
+	double length;
+	bool use_spheroid = LW_TRUE;
+	SPHEROID s;
+    int type;
+
+	/* Get our geometry object loaded into memory. */
+	g = (GSERIALIZED*)PG_DETOAST_DATUM(PG_GETARG_DATUM(0));
+	
+	/* Only return for area features. */
+    type = gserialized_get_type(g);
+    if ( ! (type == POLYGONTYPE || type == MULTIPOLYGONTYPE || type == COLLECTIONTYPE) )
+    {
+		PG_RETURN_FLOAT8(0.0);
+    }
+	
+	lwgeom = lwgeom_from_gserialized(g);
+
+	/* EMPTY things have no perimeter */
+	if ( lwgeom_is_empty(lwgeom) )
+	{
+		lwgeom_free(lwgeom);
+		PG_RETURN_FLOAT8(0.0);
+	}
+
+	/* Read our calculation type */
+	use_spheroid = PG_GETARG_BOOL(1);
+
+	/* Initialize spheroid */
+	spheroid_init(&s, WGS84_MAJOR_AXIS, WGS84_MINOR_AXIS);
+
+	/* User requests spherical calculation, turn our spheroid into a sphere */
+	if ( ! use_spheroid )
+		s.a = s.b = s.radius;
+
+	/* Calculate the length */
+	length = lwgeom_length_spheroid(lwgeom, &s);
+
+	/* Something went wrong... */
+	if ( length < 0.0 )
+	{
+		elog(ERROR, "lwgeom_length_spheroid returned length < 0.0");
+		PG_RETURN_NULL();
+	}
+
+	/* Clean up, but not all the way to the point arrays */
+	lwgeom_free(lwgeom);
+
+	PG_FREE_IF_COPY(g, 0);
+	PG_RETURN_FLOAT8(length);
+}
 
 /*
-** geography_length_sphere(GSERIALIZED *g)
+** geography_length(GSERIALIZED *g)
 ** returns double length in meters
 */
 PG_FUNCTION_INFO_V1(geography_length);
@@ -287,7 +346,7 @@ Datum geography_length(PG_FUNCTION_ARGS)
 	lwgeom = lwgeom_from_gserialized(g);
 
 	/* EMPTY things have no length */
-	if ( lwgeom_is_empty(lwgeom) )
+	if ( lwgeom_is_empty(lwgeom) || lwgeom->type == POLYGONTYPE || lwgeom->type == MULTIPOLYGONTYPE )
 	{
 		lwgeom_free(lwgeom);
 		PG_RETURN_FLOAT8(0.0);
@@ -309,12 +368,12 @@ Datum geography_length(PG_FUNCTION_ARGS)
 	/* Something went wrong... */
 	if ( length < 0.0 )
 	{
-		elog(ERROR, "geography_length_sphere returned length < 0.0");
+		elog(ERROR, "lwgeom_length_spheroid returned length < 0.0");
 		PG_RETURN_NULL();
 	}
 
-	/* Clean up, but not all the way to the point arrays */
-	lwgeom_release(lwgeom);
+	/* Clean up */
+	lwgeom_free(lwgeom);
 
 	PG_FREE_IF_COPY(g, 0);
 	PG_RETURN_FLOAT8(length);