From: Raúl Marín Rodríguez <rmrodriguez@carto.com>
Date: Wed, 16 Jan 2019 10:48:55 +0000 (+0000)
Subject: ST_AsMVTGeom: Always return the simplest geometry
X-Git-Tag: 3.0.0alpha1~201
X-Git-Url: https://granicus.if.org/sourcecode?a=commitdiff_plain;h=69219285ff671a6b2e69df53b4670886595da954;p=postgis

ST_AsMVTGeom: Always return the simplest geometry

References #4300


git-svn-id: http://svn.osgeo.org/postgis/trunk@17160 b70326c6-7e19-0410-871a-916f4a2858ee
---

diff --git a/NEWS b/NEWS
index 48bf79521..53304fbc7 100644
--- a/NEWS
+++ b/NEWS
@@ -62,6 +62,7 @@ PostGIS 3.0.0
   - #4262, Document MULTISURFACE compatibility of ST_LineToCurve (Steven Ottens)
   - #4276, ST_AsGeoJSON documentation refresh (Darafei Praliaskouski)
   - #4292, ST_AsMVT: parse JSON numeric values with decimals as doubles (Raúl Marín)
+  - #4300, ST_AsMVTGeom: Always return the simplest geometry (Raúl Marín)
 
 PostGIS 2.5.0
 2018/09/23
diff --git a/postgis/mvt.c b/postgis/mvt.c
index 0b50b1f62..651f9dbea 100644
--- a/postgis/mvt.c
+++ b/postgis/mvt.c
@@ -810,15 +810,28 @@ lwgeom_get_basic_type(LWGEOM *geom)
  * geom be lost? Sure, but your MVT renderer couldn't
  * draw it anyways.
  */
-static void
+static inline LWGEOM *
 lwgeom_to_basic_type(LWGEOM *geom, uint8 original_type)
 {
+	LWGEOM *geom_out = geom;
 	if (lwgeom_get_type(geom) == COLLECTIONTYPE)
 	{
 		LWCOLLECTION *g = (LWCOLLECTION*)geom;
-		LWCOLLECTION *gc = lwcollection_extract(g, original_type);
-		*g = *gc;
+		geom_out = (LWGEOM *)lwcollection_extract(g, original_type);
 	}
+
+	/* If a collection only contains 1 geometry return than instead */
+	if (lwgeom_is_collection(geom_out))
+	{
+		LWCOLLECTION *g = (LWCOLLECTION *)geom_out;
+		if (g->ngeoms == 1)
+		{
+			geom_out = g->geoms[0];
+		}
+	}
+
+	geom_out->srid = geom->srid;
+	return geom_out;
 }
 
 /**
@@ -936,8 +949,7 @@ LWGEOM *mvt_geom(LWGEOM *lwgeom, const GBOX *gbox, uint32_t extent, uint32_t buf
 	}
 
 	/* if geometry collection extract highest dimensional geometry type */
-	if (lwgeom->type == COLLECTIONTYPE)
-		lwgeom_to_basic_type(lwgeom, basic_type);
+	lwgeom = lwgeom_to_basic_type(lwgeom, basic_type);
 
 	if (basic_type != lwgeom_get_basic_type(lwgeom))
 	{
diff --git a/regress/core/mvt_expected b/regress/core/mvt_expected
index 5cab796ab..24c0ead7b 100644
--- a/regress/core/mvt_expected
+++ b/regress/core/mvt_expected
@@ -22,7 +22,7 @@ PG16|POLYGON((0 10,0 0,10 0,10 10,0 10),(1 9,9 9,9 1,1 1,1 9))
 PG17|MULTIPOLYGON(((0 10,0 0,10 0,10 10,0 10),(1 9,9 9,9 1,1 1,1 9)),((2 8,2 2,8 2,8 8,2 8),(3 7,7 7,7 3,3 3,3 7)))
 PG18|MULTIPOINT(1 9,3 8)
 PG19|MULTIPOINT(25 4079,26 4078)
-PG20|MULTIPOINT(10 4086)
+PG20|POINT(10 4086)
 PG21|LINESTRING(1 9,5 5)
 PG22|
 PG23|MULTILINESTRING((1 9,5 5),(2 2,5 5))
@@ -53,7 +53,7 @@ PG43 - ON |MULTIPOLYGON(((5 5,0 0,10 0,5 5)),((0 10,5 5,10 10,0 10)))
 PG43 - OFF|MULTIPOLYGON(((5 5,-1 -1,11 -1,5 5)),((5 5,11 11,-1 11,5 5)))
 PG44|
 PG45|
-PG46|SRID=3857;MULTIPOLYGON(((3245 2224,3262 2030,3253 2158,3245 2224)))
+PG46|SRID=3857;POLYGON((3245 2224,3262 2030,3253 2158,3245 2224))
 PG47|
 TG1|GiEKBHRlc3QSDBICAAAYASIECTLePxoCYzEiAigBKIAgeAI=
 TG2|GiMKBHRlc3QSDhICAAAYASIGETLePwIBGgJjMSICKAEogCB4Ag==
@@ -104,7 +104,7 @@ D7|POINT(1 4094)
 TU2
 ERROR:  pgis_asmvt_transfn: parameter row cannot be other than a rowtype
 TU3|
-#3922|MULTIPOLYGON(((2613 3664,2615 3662,2616 3662,2617 3665,2615 3665,2615 3664,2613 3664)))
+#3922|POLYGON((2613 3664,2615 3662,2616 3662,2617 3665,2615 3665,2615 3664,2613 3664))
 FI1|GicKBHRlc3QSDggBEgIAABgBIgQJMt4/GgJjMiIGCgRhYmNkKIAgeAI=
 FI2|GicKBHRlc3QSDggBEgIAABgBIgQJMt4/GgJjMiIGCgRhYmNkKIAgeAI=
 FI3|GicKBHRlc3QSDggBEgIAABgBIgQJMt4/GgJjMiIGCgRhYmNkKIAgeAI=