From d45734634a5f5c5cd2ca5af7c1e7b865d3d69055 Mon Sep 17 00:00:00 2001
From: Tom Payne <twpayne@gmail.com>
Date: Tue, 26 Nov 2013 16:26:35 +0100
Subject: [PATCH] Add ol.geom.flat.linearRingPerimeter

---
 src/ol/geom/flatgeom.js | 18 ++++++++++++++++++
 1 file changed, 18 insertions(+)

diff --git a/src/ol/geom/flatgeom.js b/src/ol/geom/flatgeom.js
index df418f842a..5744c99822 100644
--- a/src/ol/geom/flatgeom.js
+++ b/src/ol/geom/flatgeom.js
@@ -216,6 +216,24 @@ ol.geom.flat.linearRingIsClockwise =
 };
 
 
+/**
+ * @param {Array.<number>} flatCoordinates Flat coordinates.
+ * @param {number} offset Offset.
+ * @param {number} end End.
+ * @param {number} stride Stride.
+ * @return {number} Perimeter.
+ */
+ol.geom.flat.linearRingPerimeter =
+    function(flatCoordinates, offset, end, stride) {
+  var perimeter =
+      ol.geom.flat.lineStringLength(flatCoordinates, offset, end, stride);
+  var dx = flatCoordinates[end - stride] - flatCoordinates[offset];
+  var dy = flatCoordinates[end - stride + 1] - flatCoordinates[offset + 1];
+  perimeter += Math.sqrt(dx * dx + dy * dy);
+  return perimeter;
+};
+
+
 /**
  * @param {Array.<number>} flatCoordinates Flat coordinates.
  * @param {number} offset Offset.