Fix InteriorPoint to handle partially empty collections (#698)

Signed-off-by: Martin Davis <mtnclimb@gmail.com>
locationtech · Mar 5, 2021 · b3cab45 · b3cab45
1 parent 13def67
commit b3cab45
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Showing 4 changed files with 107 additions and 13 deletions.
diff --git a/modules/core/src/main/java/org/locationtech/jts/algorithm/InteriorPoint.java b/modules/core/src/main/java/org/locationtech/jts/algorithm/InteriorPoint.java
@@ -15,6 +15,9 @@
 import org.locationtech.jts.algorithm.construct.MaximumInscribedCircle;
 import org.locationtech.jts.geom.Coordinate;
 import org.locationtech.jts.geom.Geometry;
+import org.locationtech.jts.geom.GeometryCollection;
+import org.locationtech.jts.geom.GeometryComponentFilter;
+import org.locationtech.jts.geom.GeometryFilter;
 
 /**
  * Computes an interior point of a <code>{@link Geometry}</code>.
@@ -57,8 +60,12 @@ public static Coordinate getInteriorPoint(Geometry geom) {
       return null;
 
     Coordinate interiorPt = null;
-    //TODO: determine highest non-empty dimension
-    int dim = geom.getDimension();
+    //int dim = geom.getDimension();
+    int dim = effectiveDimension(geom);
+    // this should not happen, but just in case...
+    if (dim < 0) {
+      return null;
+    }
     if (dim == 0) {
       interiorPt = InteriorPointPoint.getInteriorPoint(geom);
     }
@@ -71,4 +78,27 @@ else if (dim == 1) {
     return interiorPt;
   }
 
+  private static int effectiveDimension(Geometry geom) {
+    EffectiveDimensionFilter dimFilter = new EffectiveDimensionFilter();
+    geom.apply(dimFilter);
+    return dimFilter.getDimension();
+  }
+
+  private static class EffectiveDimensionFilter implements GeometryFilter
+  {
+    private int dim = -1;
+
+    public int getDimension() {
+      return dim;
+    }
+
+    public void filter(Geometry elem) {
+      if (elem instanceof GeometryCollection)
+        return;
+      if (! elem.isEmpty()) {
+        int elemDim = elem.getDimension();
+        if (elemDim > dim) dim = elemDim;
+      }
+    }
+  }
 }
diff --git a/modules/core/src/main/java/org/locationtech/jts/geom/Geometry.java b/modules/core/src/main/java/org/locationtech/jts/geom/Geometry.java
@@ -780,10 +780,10 @@ public boolean intersects(Geometry g) {
    *    <li><code>[0********]</code> (for L/L situations)
    *   </ul>
    * </ul>
-   * For any other combination of dimensions this predicate returns <code>false</code>.
+   * For the A/A and P/P situations this predicate returns <code>false</code>.
    * <p>
    * The SFS defined this predicate only for P/L, P/A, L/L, and L/A situations.
-   * In order to make the relation symmetric,
+   * To make the relation symmetric
    * JTS extends the definition to apply to L/P, A/P and A/L situations as well.
    *
    *@param  g  the <code>Geometry</code> with which to compare this <code>Geometry</code>
@@ -1857,6 +1857,9 @@ protected boolean equal(Coordinate a, Coordinate b, double tolerance) {
 
   private Point createPointFromInternalCoord(Coordinate coord, Geometry exemplar)
   {
+    // create empty point for null input
+    if (coord == null) 
+      return exemplar.getFactory().createPoint();
     exemplar.getPrecisionModel().makePrecise(coord);
     return exemplar.getFactory().createPoint(coord);
   }

diff --git a/modules/tests/src/test/resources/testxml/general/TestCentroid.xml b/modules/tests/src/test/resources/testxml/general/TestCentroid.xml
@@ -91,6 +91,13 @@
 <test><op name="getCentroid" arg1="A" >    POINT (0 0)   </op></test>
 </case>
 
+<case>
+  <desc>A - empty</desc>
+  <a>    POLYGON EMPTY
+  </a>
+<test><op name="getCentroid" arg1="A" >    POINT EMPTY   </op></test>
+</case>
+
 <case>
   <desc>A - box</desc>
   <a>    POLYGON ((40 160, 160 160, 160 40, 40 40, 40 160))  </a>
@@ -218,6 +225,33 @@
 <test><op name="getCentroid" arg1="A" >    POINT (10 10)   </op></test>
 </case>
 
+<case>
+  <desc>GC - collection with empty polygon, line, and point</desc>
+  <a>    GEOMETRYCOLLECTION (POLYGON EMPTY, 
+  LINESTRING (20 20, 30 30, 40 40),
+  MULTIPOINT ((20 10), (10 20)) )
+  </a>
+<test><op name="getCentroid" arg1="A" >    POINT (30 30)   </op></test>
+</case>
+
+<case>
+  <desc>GC - collection with empty polygon, empty line, and point</desc>
+  <a>    GEOMETRYCOLLECTION (POLYGON EMPTY, 
+  LINESTRING EMPTY,
+  POINT (10 10) )
+  </a>
+<test><op name="getCentroid" arg1="A" >    POINT (10 10)   </op></test>
+</case>
+
+<case>
+  <desc>GC - collection with empty polygon, empty line, and empty point</desc>
+  <a>    GEOMETRYCOLLECTION (POLYGON EMPTY, 
+  LINESTRING EMPTY,
+  POINT EMPTY )
+  </a>
+<test><op name="getCentroid" arg1="A" >    POINT EMPTY  </op></test>
+</case>
+
 <case>
   <desc>GC - overlapping polygons </desc>
   <a>    GEOMETRYCOLLECTION (POLYGON ((20 100, 20 -20, 60 -20, 60 100, 20 100)), 
@@ -238,13 +272,6 @@
 <test><op name="getCentroid" arg1="A" >    POINT (55 55)   </op></test>
 </case>
 
-<case>
-  <desc>A - empty</desc>
-  <a>    POLYGON EMPTY
-	</a>
-<test><op name="getCentroid" arg1="A" >    POINT EMPTY   </op></test>
-</case>
-
 <case>
   <desc>A - almost degenerate triangle</desc>
   <a>    POLYGON((

diff --git a/modules/tests/src/test/resources/testxml/general/TestInteriorPoint.xml b/modules/tests/src/test/resources/testxml/general/TestInteriorPoint.xml
@@ -20,10 +20,17 @@
 <test><op name="getInteriorPoint" arg1="A" >    POINT (140 240)   </op></test>
 </case>
 
+<case>
+  <desc>L - empty</desc>
+  <a>    LINESTRING EMPTY
+  </a>
+<test><op name="getInteriorPoint" arg1="A" >   POINT EMPTY   </op></test>
+</case>
+
 <case>
   <desc>L - linestring with single segment</desc>
   <a>    LINESTRING (0 0, 7 14)
-	</a>
+  </a>
 <test><op name="getInteriorPoint" arg1="A" >   POINT (7 14)   </op></test>
 </case>
 
@@ -119,10 +126,37 @@
   <a>    GEOMETRYCOLLECTION (POLYGON ((10 10, 10 10, 10 10, 10 10)), 
   LINESTRING (20 20, 20 20),
   MULTIPOINT ((20 10), (10 20)) )
-	</a>
+  </a>
+<test><op name="getInteriorPoint" arg1="A" >    POINT (10 10)   </op></test>
+</case>
+
+<case>
+  <desc>GC - collection with empty polygon, line, and point</desc>
+  <a>    GEOMETRYCOLLECTION (POLYGON EMPTY, 
+  LINESTRING (20 20, 30 30, 40 40),
+  MULTIPOINT ((20 10), (10 20)) )
+  </a>
+<test><op name="getInteriorPoint" arg1="A" >    POINT (30 30)   </op></test>
+</case>
+
+<case>
+  <desc>GC - collection with empty polygon, empty line, and point</desc>
+  <a>    GEOMETRYCOLLECTION (POLYGON EMPTY, 
+  LINESTRING EMPTY,
+  POINT (10 10) )
+  </a>
 <test><op name="getInteriorPoint" arg1="A" >    POINT (10 10)   </op></test>
 </case>
 
+<case>
+  <desc>GC - collection with empty polygon, empty line, and empty point</desc>
+  <a>    GEOMETRYCOLLECTION (POLYGON EMPTY, 
+  LINESTRING EMPTY,
+  POINT EMPTY )
+  </a>
+<test><op name="getInteriorPoint" arg1="A" >    POINT EMPTY  </op></test>
+</case>
+
 
 
 </run>