Add ConcaveHullOfPolygons class (#870)

Signed-off-by: Martin Davis <[email protected]>

modules/app/src/main/java/org/locationtech/jtstest/function/HullFunctions.java

@@ -12,35 +12,36 @@
 package org.locationtech.jtstest.function;
 
 import org.locationtech.jts.algorithm.hull.ConcaveHull;
+import org.locationtech.jts.algorithm.hull.ConcaveHullOfPolygons;
 import org.locationtech.jts.algorithm.hull.PolygonHull;
 import org.locationtech.jts.geom.Geometry;
 import org.locationtech.jtstest.geomfunction.Metadata;
 
 public class HullFunctions {
   public static Geometry convexHull(Geometry g) {      return g.convexHull();  }
 
-  public static Geometry concaveHullByLen(Geometry geom, 
-      @Metadata(title="Length")
+  public static Geometry concaveHullPoints(Geometry geom, 
+      @Metadata(title="Max Edge Length")
       double maxLen) {
     return ConcaveHull.concaveHullByLength(geom, maxLen);
   }
 
-  public static Geometry concaveHullWithHolesByLen(Geometry geom, 
-      @Metadata(title="Length")
+  public static Geometry concaveHullPointsWithHoles(Geometry geom, 
+      @Metadata(title="Max Edge Length")
       double maxLen) {
     return ConcaveHull.concaveHullByLength(geom, maxLen, true);
   }
 
-  public static Geometry concaveHullByLenRatio(Geometry geom, 
+  public static Geometry concaveHullPointsByLenRatio(Geometry geom, 
       @Metadata(title="Length Ratio")
-      double maxLen) {
-    return ConcaveHull.concaveHullByLengthRatio(geom, maxLen);
+      double maxLenRatio) {
+    return ConcaveHull.concaveHullByLengthRatio(geom, maxLenRatio);
   }
 
-  public static Geometry concaveHullWithHolesByLenRatio(Geometry geom, 
+  public static Geometry concaveHullPointsWithHolesByLenRatio(Geometry geom, 
       @Metadata(title="Length Ratio")
-      double maxLen) {
-    return ConcaveHull.concaveHullByLengthRatio(geom, maxLen, true);
+      double maxLenRatio) {
+    return ConcaveHull.concaveHullByLengthRatio(geom, maxLenRatio, true);
   }
 
   public static double concaveHullLenGuess(Geometry geom) {
@@ -79,5 +80,46 @@ public static Geometry polygonHullByAreaDelta(Geometry geom,
     return PolygonHull.hullByAreaDelta(geom, areaFrac);
   }
 
-
+  public static Geometry concaveHullPolygons(Geometry geom, 
+      @Metadata(title="Max Edge Length")
+      double maxEdgeLen) {
+    return ConcaveHullOfPolygons.concaveHullByLength(geom, maxEdgeLen);
+  }
+
+  public static Geometry concaveHullPolygonsWithHoles(Geometry geom, 
+      @Metadata(title="Max Edge Length")
+      double maxEdgeLen) {
+    return ConcaveHullOfPolygons.concaveHullByLength(geom, maxEdgeLen, false, true);
+  }
+
+  public static Geometry concaveHullPolygonsTight(Geometry geom, 
+      @Metadata(title="Max Edge Length")
+      double maxEdgeLen) {
+    return ConcaveHullOfPolygons.concaveHullByLength(geom, maxEdgeLen, true, false);
+  }
+
+  public static Geometry concaveHullPolygonsByLenRatio(Geometry geom, 
+      @Metadata(title="Edge Length Ratio")
+      double maxEdgeLenRatio) {
+    return ConcaveHullOfPolygons.concaveHullByLengthRatio(geom, maxEdgeLenRatio);
+  }
+
+  public static Geometry concaveHullPolygonsTightByLenRatio(Geometry geom, 
+      @Metadata(title="Edge Length Ratio")
+      double maxEdgeLenRatio) {
+    return ConcaveHullOfPolygons.concaveHullByLengthRatio(geom, maxEdgeLenRatio, true, false);
+  }
+
+  public static Geometry concaveFill(Geometry geom, 
+      @Metadata(title="Max Edge Length")
+      double maxEdgeLen) {
+    return ConcaveHullOfPolygons.concaveFillByLength(geom, maxEdgeLen);
+  }
+
+  public static Geometry concaveFillByLenRatio(Geometry geom, 
+      @Metadata(title="Edge Length Ratio")
+      double maxEdgeLenRatio) {
+    return ConcaveHullOfPolygons.concaveFillByLengthRatio(geom, maxEdgeLenRatio);
+  }
+
 }

modules/core/src/main/java/org/locationtech/jts/algorithm/hull/ConcaveHull.java

@@ -23,9 +23,13 @@
 
 /**
  * Constructs a concave hull of a set of points.
- * The hull is constructed by removing the longest outer edges 
- * of the Delaunay Triangulation of the points
- * until a target criterion is reached.
+ * A concave hull is a possibly non-convex polygon containing all the input points.
+ * A given set of points has a sequence of hulls of increasing concaveness,
+ * determined by a numeric target parameter.
+ * <p>
+ * The concave hull is constructed by removing the longest outer edges 
+ * of the Delaunay Triangulation of the points,
+ * until the target criterion parameter is reached.
  * <p>
  * The target criteria are:
  * <ul>
@@ -77,7 +81,7 @@ public static double uniformGridEdgeLength(Geometry geom) {
   }
 
   /**
-   * Computes the concave hull of the vertices in a geometry
+   * Computes a concave hull of the vertices in a geometry
    * using the target criterion of maximum edge length.
    * 
    * @param geom the input geometry
@@ -89,7 +93,7 @@ public static Geometry concaveHullByLength(Geometry geom, double maxLength) {
   }
 
   /**
-   * Computes the concave hull of the vertices in a geometry
+   * Computes a concave hull of the vertices in a geometry
    * using the target criterion of maximum edge length,
    * and optionally allowing holes.
    * 
@@ -106,7 +110,7 @@ public static Geometry concaveHullByLength(Geometry geom, double maxLength, bool
   }
 
   /**
-   * Computes the concave hull of the vertices in a geometry
+   * Computes a concave hull of the vertices in a geometry
    * using the target criterion of maximum edge length ratio.
    * The edge length ratio is a fraction of the length difference
    * between the longest and shortest edges 
@@ -121,7 +125,7 @@ public static Geometry concaveHullByLengthRatio(Geometry geom, double lengthRati
   }
 
   /**
-   * Computes the concave hull of the vertices in a geometry
+   * Computes a concave hull of the vertices in a geometry
    * using the target criterion of maximum edge length factor,
    * and optionally allowing holes.
    * The edge length factor is a fraction of the length difference