From 2005530920e7c290bb1cf7d9ada155250faa81ad Mon Sep 17 00:00:00 2001
From: David Smith <smithdc@gmail.com>
Date: Sun, 28 Jan 2024 08:41:25 +0000
Subject: [PATCH] Refs #35058 -- Made centroid available on all geometry types.

Centroid is available on all geometry types since GDAL 1.8.0.
Previously it was restricted to Polygon.

https://gdal.org/doxygen/classOGRGeometry.html#a91787f669b2a148169667e270e7e40df
---
 django/contrib/gis/gdal/geometries.py   | 16 ++++++++--------
 docs/ref/contrib/gis/gdal.txt           | 13 +++++++++----
 docs/releases/5.1.txt                   |  3 +++
 tests/gis_tests/gdal_tests/test_geom.py | 23 +++++++++++++++++++++++
 4 files changed, 43 insertions(+), 12 deletions(-)

diff --git a/django/contrib/gis/gdal/geometries.py b/django/contrib/gis/gdal/geometries.py
index 4c1f74d4b0..85ef265ad1 100644
--- a/django/contrib/gis/gdal/geometries.py
+++ b/django/contrib/gis/gdal/geometries.py
@@ -565,6 +565,14 @@ class OGRGeometry(GDALBase):
         """
         return self._geomgen(capi.geom_union, other)
 
+    @property
+    def centroid(self):
+        """Return the centroid (a Point) of this Polygon."""
+        # The centroid is a Point, create a geometry for this.
+        p = OGRGeometry(OGRGeomType("Point"))
+        capi.get_centroid(self.ptr, p.ptr)
+        return p
+
 
 # The subclasses for OGR Geometry.
 class Point(OGRGeometry):
@@ -708,14 +716,6 @@ class Polygon(OGRGeometry):
         # Summing up the number of points in each ring of the Polygon.
         return sum(self[i].point_count for i in range(self.geom_count))
 
-    @property
-    def centroid(self):
-        "Return the centroid (a Point) of this Polygon."
-        # The centroid is a Point, create a geometry for this.
-        p = OGRGeometry(OGRGeomType("Point"))
-        capi.get_centroid(self.ptr, p.ptr)
-        return p
-
 
 # Geometry Collection base class.
 class GeometryCollection(OGRGeometry):
diff --git a/docs/ref/contrib/gis/gdal.txt b/docs/ref/contrib/gis/gdal.txt
index f6e9ef0964..be6e738160 100644
--- a/docs/ref/contrib/gis/gdal.txt
+++ b/docs/ref/contrib/gis/gdal.txt
@@ -839,6 +839,15 @@ coordinate transformation:
     Returns the region consisting of the union of this geometry and
     the other, as a new :class:`OGRGeometry` object.
 
+    .. attribute:: centroid
+
+    Returns a :class:`Point` representing the centroid of this geometry.
+
+    .. versionchanged:: 5.1
+
+        ``centroid`` was promoted from a :class:`.Polygon` only attribute to
+        being available on all geometry types.
+
     .. attribute:: tuple
 
     Returns the coordinates of a point geometry as a tuple, the
@@ -939,10 +948,6 @@ coordinate transformation:
 
     An alias for :attr:`shell`.
 
-    .. attribute:: centroid
-
-    Returns a :class:`Point` representing the centroid of this polygon.
-
 .. class:: GeometryCollection
 
     .. method:: add(geom)
diff --git a/docs/releases/5.1.txt b/docs/releases/5.1.txt
index 463551e85c..34ef350afd 100644
--- a/docs/releases/5.1.txt
+++ b/docs/releases/5.1.txt
@@ -83,6 +83,9 @@ Minor features
   via the new :attr:`.OGRGeometry.is_measured` and :attr:`.Point.m` properties,
   and the :meth:`.OGRGeometry.set_measured` method.
 
+* :attr:`.OGRGeometry.centroid` is now available on all supported geometry
+  types.
+
 :mod:`django.contrib.messages`
 ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
 
diff --git a/tests/gis_tests/gdal_tests/test_geom.py b/tests/gis_tests/gdal_tests/test_geom.py
index a2aa9d8e36..6bb7aa0724 100644
--- a/tests/gis_tests/gdal_tests/test_geom.py
+++ b/tests/gis_tests/gdal_tests/test_geom.py
@@ -877,6 +877,29 @@ class OGRGeomTest(SimpleTestCase, TestDataMixin):
         geom = OGRGeometry("POINT M (1 2 3)")
         self.assertEqual(geom.geos.wkt, "POINT (1 2)")
 
+    def test_centroid(self):
+        point = OGRGeometry("POINT (1 2 3)")
+        self.assertEqual(point.centroid.wkt, "POINT (1 2)")
+        linestring = OGRGeometry("LINESTRING (0 0 0, 1 1 1, 2 2 2)")
+        self.assertEqual(linestring.centroid.wkt, "POINT (1 1)")
+        polygon = OGRGeometry("POLYGON((0 0, 10 0, 10 10, 0 10, 0 0))")
+        self.assertEqual(polygon.centroid.wkt, "POINT (5 5)")
+        multipoint = OGRGeometry("MULTIPOINT (0 0,10 10)")
+        self.assertEqual(multipoint.centroid.wkt, "POINT (5 5)")
+        multilinestring = OGRGeometry(
+            "MULTILINESTRING ((0 0,0 10,0 20),(10 0,10 10,10 20))"
+        )
+        self.assertEqual(multilinestring.centroid.wkt, "POINT (5 10)")
+        multipolygon = OGRGeometry(
+            "MULTIPOLYGON(((0 0, 10 0, 10 10, 0 10, 0 0)),"
+            "((20 20, 20 30, 30 30, 30 20, 20 20)))"
+        )
+        self.assertEqual(multipolygon.centroid.wkt, "POINT (15 15)")
+        geometrycollection = OGRGeometry(
+            "GEOMETRYCOLLECTION (POINT (110 260),LINESTRING (110 0,110 60))"
+        )
+        self.assertEqual(geometrycollection.centroid.wkt, "POINT (110 30)")
+
 
 class DeprecationTests(SimpleTestCase):
     def test_coord_setter_deprecation(self):