Backport fix for country borders disappearing

Author: molinav

CHANGELOG.md

@@ -16,19 +16,23 @@ https://semver.org/spec/v2.0.0.html
 - Fix `GeosLibrary` wrapper to also work with CMake >= 3.27.0 and
   Python 2.7 on Windows by adding '/MANIFEST:NO' to override the new
   default '/MANIFEST:EMBED,ID=2' provided to linker.
-- Fix references to removed `numpy.float` alias (solves issue [#589],
-  thanks to @quickbrett).
-- Fix bug with elliptical maps causing warped images (Blue Marble,
-  ETOPO, Shaded Relief) to be shown behind the map background when the
-  map boundary is not initialised manually (solves issue [#577], thanks
-  to @YilongWang).
+- Fix broken `Proj.__call__` when the input arguments are provided as
+  a combined single array.
 - Fix flipped coastlines with pseudocylindrical projections when `lon_0`
   is greater than 0 deg (solves issues [#443] and [#463], thanks to
   @YilongWang).
-- Fix broken `Proj.__call__` when the input arguments are provided as
-  a combined single array.
 - Fix `antialiased` argument being ignored in `Basemap.drawcounties` and
   `Basemap.readshapefile` (solves issue [#501], thanks to @TheFizzWare).
+- Fix `BaseGeometry.intersection` in `_geoslib` so that it also works
+  with `GEOS_GEOMETRYCOLLECTION` objects returned by `GEOSIntersection`
+  (solves issue [#566], where country boundaries are missing due to this
+  bug, thanks to @guidocioni).
+- Fix bug with elliptical maps causing warped images (Blue Marble,
+  ETOPO, Shaded Relief) to be shown behind the map background when the
+  map boundary is not initialised manually (solves issue [#577], thanks
+  to @YilongWang).
+- Fix references to removed `numpy.float` alias (solves issue [#589],
+  thanks to @quickbrett).
 - Fix wrong reference to `ireland.py` example in FAQ, which should be
   `hires.py` instead, and fix wrong use of locals and invalid syntax
   in this example (solves issue [#592], thanks to @timcoote).
@@ -1017,6 +1021,8 @@ https://github.com/matplotlib/basemap/issues/579
 https://github.com/matplotlib/basemap/issues/577
 [#573]:
 https://github.com/matplotlib/basemap/issues/573
+[#566]:
+https://github.com/matplotlib/basemap/issues/566
 [#564]:
 https://github.com/matplotlib/basemap/pull/564
 [#563]:

packages/basemap/src/_geoslib.pyx

@@ -307,6 +307,30 @@ cdef class BaseGeometry:
                 b = _get_coords(gout)
                 p = LineString(b)
                 pout.append(p)
+        elif typeid == GEOS_GEOMETRYCOLLECTION:
+            numgeoms = GEOSGetNumGeometries(g3)
+            pout = []
+            for i from 0 <= i < numgeoms:
+                gout = GEOSGetGeometryN(g3, i)
+                typeid = GEOSGeomTypeId(gout)
+                if typeid == GEOS_POLYGON:
+                    b = _get_coords(gout)
+                    p = Polygon(b)
+                    pout.append(p)
+                elif typeid == GEOS_LINESTRING:
+                    b = _get_coords(gout)
+                    p = LineString(b)
+                    pout.append(p)
+                else:
+                    # More cases might need to be handled here:
+                    # - GEOS_MULTILINESTRING
+                    # - GEOS_MULTIPOLYGON
+                    # - GEOS_GEOMETRYCOLLECTION
+                    # The underlying problem is the need of a generic
+                    # converter from GEOSGeom pointers to `_geoslib`
+                    # objects, since postprocessing `GeometryCollections`
+                    # might need recursiveness.
+                    pass
         else:
             #type = PyBytes_FromString(GEOSGeomType(g3))
             #raise NotImplementedError("intersections of type '%s' not yet implemented" % (type))