Merge pull request #62 from geoscript/GSG-58.LargestEmptyCircle

Add largest empty circle method to Geometry

Author: jericks

src/main/groovy/geoscript/geom/Geometry.groovy

@@ -1,5 +1,6 @@
 package geoscript.geom
 
+import org.locationtech.jts.algorithm.construct.LargestEmptyCircle
 import org.locationtech.jts.algorithm.construct.MaximumInscribedCircle
 import org.locationtech.jts.geom.Geometry as JtsGeometry
 import org.locationtech.jts.geom.GeometryFactory
@@ -525,6 +526,18 @@ class Geometry {
         Geometry.wrap(centerPoint.buffer(radiusLineString.getLength()))
     }
 
+    /**
+     * Get the largest empty circle for this Geometry
+     * @param tolerance The tolerance which defaults to 1.0
+     * @return The largest empty circle
+     */
+    Geometry getLargestEmptyCircle(double tolerance = 1.0) {
+        LargestEmptyCircle algorithm = new LargestEmptyCircle(g, tolerance)
+        def radiusLineString = algorithm.getRadiusLine()
+        def centerPoint = radiusLineString.getStartPoint()
+        Geometry.wrap(centerPoint.buffer(radiusLineString.getLength()))
+    }
+
     /**
      * Get Delaunay Triangle Diagram for this Geometry
      * @return A Delaunay Triangle Diagram Geometry

src/test/groovy/geoscript/geom/GeometryTestCase.groovy

@@ -519,6 +519,18 @@ class GeometryTestCase {
         assertTrue(circle instanceof Polygon)
     }
 
+    @Test void getLargestEmptyCircle() {
+        Geometry g = Geometry.fromWKT("POLYGON ((-122.38855361938475 47.5805786829606, -122.38636493682861 47.5783206388176, " +
+                "-122.38700866699219 47.5750491969984, -122.38177299499512 47.57502024527343, " +
+                "-122.38481998443604 47.5780600889959, -122.38151550292969 47.5805786829606, " +
+                "-122.38855361938475 47.5805786829606))")
+        Geometry circle = g.getLargestEmptyCircle(1.0)
+        assertNotNull circle
+        assertTrue circle.isValid()
+        assertFalse circle.isEmpty()
+        assertTrue(circle instanceof Polygon)
+    }
+
     /*@Test void createFromText() {
         Geometry g = Geometry.createFromText("B")
         assertEquals "Polygon", g.geometryType