Add CoordinateList.toCoordinateArray() with direction (#482)

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

modules/core/src/main/java/org/locationtech/jts/geom/CoordinateList.java

@@ -217,6 +217,27 @@ public Coordinate[] toCoordinateArray()
     return (Coordinate[]) toArray(coordArrayType);
   }
 
+  /**
+   * Creates an array containing the coordinates in this list,
+   * oriented in the given direction (forward or reverse).
+   * 
+   * @param direction the direction value: true for forward, false for reverse
+   * @return an oriented array of coordinates
+   */
+  public Coordinate[] toCoordinateArray(boolean isForward)
+  {
+    if (isForward) {
+      return (Coordinate[]) toArray(coordArrayType);
+    }
+    // construct reversed array
+    int size = size();
+    Coordinate[] pts = new Coordinate[size];
+    for (int i = 0; i < size; i++) {
+      pts[i] = get(size - i - 1);
+    }
+    return pts;
+  }
+
   /**
    * Returns a deep copy of this <tt>CoordinateList</tt> instance.
    *

modules/core/src/test/java/org/locationtech/jts/geom/CoordinateListTest.java

@@ -0,0 +1,46 @@
+package org.locationtech.jts.geom;
+
+import junit.framework.TestCase;
+import junit.textui.TestRunner;
+
+public class CoordinateListTest extends TestCase {
+  public static void main(String args[]) {
+    TestRunner.run(CoordinateListTest.class);
+  }
+
+  public CoordinateListTest(String name) { super(name); }
+
+  public void testForward() {
+    checkValue(coordList(0,0,1,1,2,2).toCoordinateArray(true), 
+        0,0,1,1,2,2);
+  }
+
+  public void testReverse() {
+    checkValue(coordList(0,0,1,1,2,2).toCoordinateArray(false), 
+        2,2,1,1,0,0);
+  }
+
+  public void testReverseEmpty() {
+    checkValue(coordList().toCoordinateArray(false) );
+  }
+
+  private void checkValue(Coordinate[] coordArray, double ... ords) {
+
+    assertEquals( coordArray.length * 2, ords.length);
+
+    for (int i = 0 ; i < coordArray.length; i += 2) {
+      Coordinate pt = coordArray[i];
+      assertEquals(pt.getX(), ords[2 * i]);
+      assertEquals(pt.getY(), ords[2 * i + 1]);
+    }
+  }
+
+  private CoordinateList coordList(double ... ords) {
+    CoordinateList cl = new CoordinateList();
+    for (int i = 0 ; i < ords.length; i += 2) {
+      cl.add(new Coordinate(ords[i], ords[i+1]), false);
+    }
+    return cl;
+  }
+
+}