From d17c7ad31e16a7ab395adf33ccffe67b13eee8d2 Mon Sep 17 00:00:00 2001
From: Andreas Hocevar <andreas.hocevar@gmail.com>
Date: Thu, 2 Sep 2021 09:44:33 +0200
Subject: [PATCH] Fix return stride of forEachSegment

---
 src/ol/geom/flat/segments.js            | 14 ++++++--------
 test/node/ol/geom/flat/segments.test.js | 13 +++++++++++++
 2 files changed, 19 insertions(+), 8 deletions(-)

diff --git a/src/ol/geom/flat/segments.js b/src/ol/geom/flat/segments.js
index 4137ce0bc1..5b07bc63df 100644
--- a/src/ol/geom/flat/segments.js
+++ b/src/ol/geom/flat/segments.js
@@ -16,18 +16,16 @@
  * @template T
  */
 export function forEach(flatCoordinates, offset, end, stride, callback) {
-  const point1 = [flatCoordinates[offset], flatCoordinates[offset + 1]];
-  const point2 = [];
   let ret;
-  for (; offset + stride < end; offset += stride) {
-    point2[0] = flatCoordinates[offset + stride];
-    point2[1] = flatCoordinates[offset + stride + 1];
-    ret = callback(point1, point2);
+  offset += stride;
+  for (; offset < end; offset += stride) {
+    ret = callback(
+      flatCoordinates.slice(offset - stride, offset),
+      flatCoordinates.slice(offset, offset + stride)
+    );
     if (ret) {
       return ret;
     }
-    point1[0] = point2[0];
-    point1[1] = point2[1];
   }
   return false;
 }
diff --git a/test/node/ol/geom/flat/segments.test.js b/test/node/ol/geom/flat/segments.test.js
index 0789199080..cc4ad1c478 100644
--- a/test/node/ol/geom/flat/segments.test.js
+++ b/test/node/ol/geom/flat/segments.test.js
@@ -50,5 +50,18 @@ describe('ol/geom/flat/segments.js', function () {
         expect(ret).to.be(true);
       });
     });
+    it('returns coordinates with the correct stride', function () {
+      const spy = sinon.spy();
+      forEachSegment([0, 0, 0, 1, 1, 1, 2, 2, 2], 0, 9, 3, spy);
+      expect(spy.callCount).to.be(2);
+      expect(spy.firstCall.args).to.eql([
+        [0, 0, 0],
+        [1, 1, 1],
+      ]);
+      expect(spy.secondCall.args).to.eql([
+        [1, 1, 1],
+        [2, 2, 2],
+      ]);
+    });
   });
 });