From c8bbeca06e23b3f8b567268abcdd2ce5ed1a6bf7 Mon Sep 17 00:00:00 2001
From: Tom Payne <twpayne@gmail.com>
Date: Mon, 10 Mar 2014 16:40:19 +0100
Subject: [PATCH] Add ol.geom.MultiPolygon#getPolygon

---
 src/ol/geom/multipolygon.exports       |  1 +
 src/ol/geom/multipolygon.js            | 31 ++++++++++++++++++++++++++
 test/spec/ol/geom/multipolygon.test.js | 11 +++++++++
 3 files changed, 43 insertions(+)

diff --git a/src/ol/geom/multipolygon.exports b/src/ol/geom/multipolygon.exports
index 07d0d094b8..13168e0436 100644
--- a/src/ol/geom/multipolygon.exports
+++ b/src/ol/geom/multipolygon.exports
@@ -3,6 +3,7 @@
 @exportProperty ol.geom.MultiPolygon.prototype.getArea
 @exportProperty ol.geom.MultiPolygon.prototype.getCoordinates
 @exportProperty ol.geom.MultiPolygon.prototype.getInteriorPoints
+@exportProperty ol.geom.MultiPolygon.prototype.getPolygon
 @exportProperty ol.geom.MultiPolygon.prototype.getPolygons
 @exportProperty ol.geom.MultiPolygon.prototype.getType
 @exportProperty ol.geom.MultiPolygon.prototype.setCoordinates
diff --git a/src/ol/geom/multipolygon.js b/src/ol/geom/multipolygon.js
index ebab3694e1..f70cf78d6c 100644
--- a/src/ol/geom/multipolygon.js
+++ b/src/ol/geom/multipolygon.js
@@ -205,6 +205,37 @@ ol.geom.MultiPolygon.prototype.getSimplifiedGeometryInternal =
 };
 
 
+/**
+ * @param {number} index Index.
+ * @return {ol.geom.Polygon} Polygon.
+ */
+ol.geom.MultiPolygon.prototype.getPolygon = function(index) {
+  goog.asserts.assert(0 <= index && index < this.endss_.length);
+  if (index < 0 || this.endss_.length <= index) {
+    return null;
+  }
+  var offset;
+  if (index === 0) {
+    offset = 0;
+  } else {
+    var prevEnds = this.endss_[index - 1];
+    offset = prevEnds[prevEnds.length - 1];
+  }
+  var ends = this.endss_[index].slice();
+  var end = ends[ends.length - 1];
+  if (offset !== 0) {
+    var i, ii;
+    for (i = 0, ii = ends.length; i < ii; ++i) {
+      ends[i] -= offset;
+    }
+  }
+  var polygon = new ol.geom.Polygon(null);
+  polygon.setFlatCoordinates(
+      this.layout, this.flatCoordinates.slice(offset, end), ends);
+  return polygon;
+};
+
+
 /**
  * @return {Array.<ol.geom.Polygon>} Polygons.
  * @todo stability experimental
diff --git a/test/spec/ol/geom/multipolygon.test.js b/test/spec/ol/geom/multipolygon.test.js
index b515b1d475..0c21f9fb00 100644
--- a/test/spec/ol/geom/multipolygon.test.js
+++ b/test/spec/ol/geom/multipolygon.test.js
@@ -20,6 +20,17 @@ describe('ol.geom.MultiPolygon', function() {
       ]);
     });
 
+    it('can return individual polygons', function() {
+      var polygon0 = multiPolygon.getPolygon(0);
+      expect(polygon0).to.be.an(ol.geom.Polygon);
+      expect(polygon0.getCoordinates()).to.eql(
+          [[[0, 0], [0, 2], [1, 1], [2, 0]]]);
+      var polygon1 = multiPolygon.getPolygon(1);
+      expect(polygon1).to.be.an(ol.geom.Polygon);
+      expect(polygon1.getCoordinates()).to.eql(
+          [[[3, 0], [4, 1], [5, 2], [5, 0]]]);
+    });
+
     it('can return all polygons', function() {
       var polygons = multiPolygon.getPolygons();
       expect(polygons).to.be.an(Array);