From bff25f9ba4ed90bd3817fe12b5540aea7cf11a77 Mon Sep 17 00:00:00 2001
From: Andreas Hocevar <andreas.hocevar@gmail.com>
Date: Thu, 10 Sep 2020 10:10:52 +0200
Subject: [PATCH] Bind tileUrlFunction before returning it from
 getTileUrlFunction

---
 src/ol/source/UrlTile.js            | 6 ++++--
 test/spec/ol/source/tilewms.test.js | 9 +++++++++
 2 files changed, 13 insertions(+), 2 deletions(-)

diff --git a/src/ol/source/UrlTile.js b/src/ol/source/UrlTile.js
index f4303fe0d0..f0d20eb3a4 100644
--- a/src/ol/source/UrlTile.js
+++ b/src/ol/source/UrlTile.js
@@ -68,7 +68,7 @@ class UrlTile extends TileSource {
     this.tileLoadFunction = options.tileLoadFunction;
 
     if (options.tileUrlFunction) {
-      this.tileUrlFunction = options.tileUrlFunction.bind(this);
+      this.tileUrlFunction = options.tileUrlFunction;
     }
 
     /**
@@ -105,7 +105,9 @@ class UrlTile extends TileSource {
    * @api
    */
   getTileUrlFunction() {
-    return this.tileUrlFunction;
+    return Object.getPrototypeOf(this).tileUrlFunction === this.tileUrlFunction
+      ? this.tileUrlFunction.bind(this)
+      : this.tileUrlFunction;
   }
 
   /**
diff --git a/test/spec/ol/source/tilewms.test.js b/test/spec/ol/source/tilewms.test.js
index 6df7258cb8..7bd16e92b2 100644
--- a/test/spec/ol/source/tilewms.test.js
+++ b/test/spec/ol/source/tilewms.test.js
@@ -159,6 +159,15 @@ describe('ol.source.TileWMS', function () {
   });
 
   describe('#tileUrlFunction', function () {
+    it('can be used when obtained through #getTileUrlFunction', function () {
+      options.extent = [-80, -40, -50, -10];
+      const source = new TileWMS(options);
+      const tileCoord = [3, 2, 2];
+      expect(function () {
+        source.getTileUrlFunction()(tileCoord, 1, getProjection('EPSG:4326'));
+      }).to.not.throwException();
+    });
+
     it('returns a tile if it is contained within layers extent', function () {
       options.extent = [-80, -40, -50, -10];
       const source = new TileWMS(options);