Port MaximumInscribedCircle and LargestEmptyCircle

From locationtech/jts#530
Closes libgeos#1029

.azure-pipelines.yml

@@ -158,11 +158,10 @@ stages:
       matrix:
         #Disabled until MSVC 16.4 is released
         #(see https://developercommunity.visualstudio.com/content/problem/726778/this-snippet-compiles-totally-fine-on-godbolt-msvc.html?childToView=744771#comment-744771)
-        #VS 2019 C++20 Strict:
-        #  TOOLSET: msvc-14.2
-        #  CXXSTD: 20
-        #  CXXFLAGS: -permissive-
-        #  VM_IMAGE: 'windows-2019'
+        VS 2019 C++20 Strict:
+          TOOLSET: msvc-14.2
+          CXXSTD: 20
+          VM_IMAGE: 'windows-2019'
         VS 2017 C++17:
           TOOLSET: msvc-14.1
           CXXSTD: 17
@@ -171,10 +170,6 @@ stages:
           TOOLSET: msvc-14.1
           CXXSTD: 14 # default
           VM_IMAGE: 'vs2017-win2016'
-        VS 2015 C++14:
-          TOOLSET: msvc-14.0
-          CXXSTD: 14 # default
-          VM_IMAGE: 'vs2015-win2012r2'
     pool:
       vmImage: $(VM_IMAGE)
     steps:
@@ -202,7 +197,7 @@ stages:
 
   - job: 'macOS'
     pool:
-      vmImage: 'macOS-10.13'
+      vmImage: 'macOS-10.14'
     strategy:
       matrix:
         Xcode 10.1:
@@ -215,30 +210,6 @@ stages:
         Xcode 9.4.1:
           CXXSTD: 11, 14, 17
           XCODE_APP: /Applications/Xcode_9.4.1.app
-        Xcode 9.4:
-          CXXSTD: 11, 14, 17
-          XCODE_APP: /Applications/Xcode_9.4.app
-        Xcode 9.3.1:
-          CXXSTD: 11, 14, 17
-          XCODE_APP: /Applications/Xcode_9.3.1.app
-        Xcode 9.3:
-          CXXSTD: 11, 14
-          XCODE_APP: /Applications/Xcode_9.3.app
-        Xcode 9.2:
-          CXXSTD: 11, 14
-          XCODE_APP: /Applications/Xcode_9.2.app
-        Xcode 9.1:
-          CXXSTD: 11
-          XCODE_APP: /Applications/Xcode_9.1.app
-        Xcode 9.0.1:
-          CXXSTD: 11
-          XCODE_APP: /Applications/Xcode_9.0.1.app
-        Xcode 9.0:
-          CXXSTD: 11
-          XCODE_APP: /Applications/Xcode_9.app
-        Xcode 8.3.3:
-          CXXSTD: 11
-          XCODE_APP: /Applications/Xcode_8.3.3.app
     steps:
     - script: |
         set -e

.gitignore

@@ -8,6 +8,7 @@ Makefile
 .vimrc
 .dirstamp
 .tm_properties
+*~
 *.o
 *.orig
 *.lo

NEWS

@@ -2,13 +2,13 @@ Changes in 3.9.0
 2020-xx-xx
 
 - New things:
-  -
+  -  MaximumInscribedCircle and LargestEmptyCircle (JTS-530, Paul Ramsey)
 
 - Improvements:
   - Stack allocate segments in OverlapUnion (Paul Ramsey)
   - Improve performance of GEOSisValid (Dan Baston)
-  - Update geos-config tool for consistency 
-    and escape paths (https://git.osgeo.org/gitea/geos/geos/pulls/99) 
+  - Update geos-config tool for consistency
+    and escape paths (https://git.osgeo.org/gitea/geos/geos/pulls/99)
     changes mostly affect CMake MSVC builds (#1015, Mike Taves)
   - Testing on Rasberry Pi 32-bit (berrie) (#1017, Bruce Rindahl, Regina Obe)
   - Replace ttmath with JTS DD double-double implementation (Paul Ramsey)

capi/geos_c.cpp

@@ -457,6 +457,18 @@ extern "C" {
         return GEOSMinimumRotatedRectangle_r(handle, g);
     }
 
+    Geometry*
+    GEOSMaximumInscribedCircle(const Geometry* g, double tolerance)
+    {
+        return GEOSMaximumInscribedCircle_r(handle, g, tolerance);
+    }
+
+    Geometry*
+    GEOSLargestEmptyCircle(const Geometry* g, double tolerance)
+    {
+        return GEOSLargestEmptyCircle_r(handle, g, tolerance);
+    }
+
     Geometry*
     GEOSMinimumWidth(const Geometry* g)
     {

capi/geos_c.h.in

@@ -561,6 +561,9 @@ extern GEOSGeometry GEOS_DLL *GEOSConvexHull_r(GEOSContextHandle_t handle,
 extern GEOSGeometry GEOS_DLL *GEOSMinimumRotatedRectangle_r(GEOSContextHandle_t handle,
                                                const GEOSGeometry* g);
 
+extern GEOSGeometry GEOS_DLL *GEOSMaximumInscribedCircle_r(GEOSContextHandle_t handle, const GEOSGeometry* g, double tolerance);
+extern GEOSGeometry GEOS_DLL *GEOSLargestEmptyCircle_r(GEOSContextHandle_t handle, const GEOSGeometry* g, double tolerance);
+
 /* Returns a LINESTRING geometry which represents the minimum diameter of the geometry.
  * The minimum diameter is defined to be the width of the smallest band that
  * contains the geometry, where a band is a strip of the plane defined
@@ -1599,6 +1602,38 @@ extern GEOSGeometry GEOS_DLL *GEOSConvexHull(const GEOSGeometry* g);
  */
 extern GEOSGeometry GEOS_DLL *GEOSMinimumRotatedRectangle(const GEOSGeometry* g);
 
+/* Constructs the Maximum Inscribed Circle for a  polygonal geometry, up to a specified tolerance.
+ * The Maximum Inscribed Circle is determined by a point in the interior of the area
+ * which has the farthest distance from the area boundary, along with a boundary point at that distance.
+ * In the context of geography the center of the Maximum Inscribed Circle is known as the
+ * Pole of Inaccessibility. A cartographic use case is to determine a suitable point
+ * to place a map label within a polygon.
+ * The radius length of the Maximum Inscribed Circle is a  measure of how "narrow" a polygon is. It is the
+ * distance at which the negative buffer becomes empty.
+ * The class supports polygons with holes and multipolygons.
+ * The implementation uses a successive-approximation technique over a grid of square cells covering the area geometry.
+ * The grid is refined using a branch-and-bound algorithm. Point containment and distance are computed in a performant
+ * way by using spatial indexes.
+ * Returns a two-point linestring, with one point at the center of the inscribed circle and the other
+ * on the boundary of the inscribed circle.
+*/
+extern GEOSGeometry GEOS_DLL *GEOSMaximumInscribedCircle(const GEOSGeometry* g, double tolerance);
+
+/* Constructs the Largest Empty Circle for a set of obstacle geometries, up to a
+ * specified tolerance. The obstacles are point and line geometries.
+ * The Largest Empty Circle is the largest circle which  has its center in the convex hull of the
+ * obstacles (the boundary), and whose interior does not intersect with any obstacle.
+ * The circle center is the point in the interior of the boundary which has the farthest distance from
+ * the obstacles (up to tolerance). The circle is determined by the center point and a point lying on an
+ * obstacle indicating the circle radius.
+ * The implementation uses a successive-approximation technique over a grid of square cells covering the obstacles and boundary.
+ * The grid is refined using a branch-and-bound algorithm.  Point containment and distance are computed in a performant
+ * way by using spatial indexes.
+ * Returns a two-point linestring, with one point at the center of the inscribed circle and the other
+ * on the boundary of the inscribed circle.
+ */
+extern GEOSGeometry GEOS_DLL *GEOSLargestEmptyCircle(const GEOSGeometry* g, double tolerance);
+
 /* Returns a LINESTRING geometry which represents the minimum diameter of the geometry.
  * The minimum diameter is defined to be the width of the smallest band that
  * contains the geometry, where a band is a strip of the plane defined

capi/geos_ts_c.cpp

@@ -48,6 +48,8 @@
 #include <geos/algorithm/MinimumBoundingCircle.h>
 #include <geos/algorithm/MinimumDiameter.h>
 #include <geos/algorithm/Orientation.h>
+#include <geos/algorithm/construct/MaximumInscribedCircle.h>
+#include <geos/algorithm/construct/LargestEmptyCircle.h>
 #include <geos/algorithm/distance/DiscreteHausdorffDistance.h>
 #include <geos/algorithm/distance/DiscreteFrechetDistance.h>
 #include <geos/simplify/DouglasPeuckerSimplifier.h>
@@ -1158,6 +1160,28 @@ extern "C" {
         });
     }
 
+    Geometry*
+    GEOSMaximumInscribedCircle_r(GEOSContextHandle_t extHandle, const Geometry* g, double tolerance)
+    {
+        return execute(extHandle, [&]() {
+            geos::algorithm::construct::MaximumInscribedCircle mic(g, tolerance);
+            auto g3 = mic.getRadiusLine();
+            g3->setSRID(g->getSRID());
+            return g3.release();
+        });
+    }
+
+    Geometry*
+    GEOSLargestEmptyCircle_r(GEOSContextHandle_t extHandle, const Geometry* g, double tolerance)
+    {
+        return execute(extHandle, [&]() {
+            geos::algorithm::construct::LargestEmptyCircle lec(g, tolerance);
+            auto g3 = lec.getRadiusLine();
+            g3->setSRID(g->getSRID());
+            return g3.release();
+        });
+    }
+
     Geometry*
     GEOSMinimumWidth_r(GEOSContextHandle_t extHandle, const Geometry* g)
     {

configure.ac

@@ -364,8 +364,9 @@ AC_OUTPUT([
 	macros/Makefile
 	src/Makefile
 	src/algorithm/Makefile
-	src/algorithm/locate/Makefile
+	src/algorithm/construct/Makefile
 	src/algorithm/distance/Makefile
+	src/algorithm/locate/Makefile
 	src/geom/Makefile
 	src/geom/prep/Makefile
 	src/geom/util/Makefile
@@ -376,6 +377,7 @@ AC_OUTPUT([
 	include/geos/algorithm/Makefile
 	include/geos/algorithm/locate/Makefile
 	include/geos/algorithm/distance/Makefile
+	include/geos/algorithm/construct/Makefile
 	include/geos/geom/Makefile
 	include/geos/geom/prep/Makefile
 	include/geos/geom/util/Makefile

include/geos/algorithm/Makefile.am

@@ -3,7 +3,8 @@
 #
 SUBDIRS = \
 	locate \
-	distance 
+	distance \
+	construct
 
 EXTRA_DIST =