Transform tile coords when converting them to URLs

src/ol/tilegrid.js

@@ -1,4 +1,5 @@
 goog.provide('ol.TileGrid');
+goog.provide('ol.TileGrid.createOpenStreetMap');
 
 goog.require('goog.array');
 goog.require('goog.asserts');

src/ol/tilestore.js

@@ -1,4 +1,5 @@
 goog.provide('ol.TileStore');
+goog.provide('ol.TileStore.createOpenStreetMap');
 
 goog.require('ol.Store');
 goog.require('ol.Tile');
@@ -60,11 +61,15 @@ ol.TileStore.createOpenStreetMap = function() {
 
   var projection = ol.Projection.createFromCode('EPSG:3857');
   var tileGrid = ol.TileGrid.createOpenStreetMap(18);
-  var tileUrlFunction = ol.TileUrlFunction.createFromTemplates([
-    'http://a.tile.openstreetmap.org/{z}/{x}/{y}.png',
-    'http://b.tile.openstreetmap.org/{z}/{x}/{y}.png',
-    'http://c.tile.openstreetmap.org/{z}/{x}/{y}.png'
-  ]);
+  var tileUrlFunction = ol.TileUrlFunction.withTileCoordTransform(
+      function(tileCoord) {
+        return new ol.TileCoord(tileCoord.z, tileCoord.x, -tileCoord.y - 1);
+      },
+      ol.TileUrlFunction.createFromTemplates([
+        'http://a.tile.openstreetmap.org/{z}/{x}/{y}.png',
+        'http://b.tile.openstreetmap.org/{z}/{x}/{y}.png',
+        'http://c.tile.openstreetmap.org/{z}/{x}/{y}.png'
+      ]));
   var extent = projection.getExtent();
   var attribution =
       '© ' +
@@ -109,7 +114,6 @@ ol.TileStore.prototype.getTile = function(tileCoord) {
  * @return {string} Tile coord URL.
  */
 ol.TileStore.prototype.getTileCoordUrl = function(tileCoord) {
-  // FIXME maybe wrap x and y
   return this.tileUrlFunction_(tileCoord);
 };
 

src/ol/tilestore_test.js

@@ -0,0 +1,39 @@
+goog.require('goog.testing.jsunit');
+goog.require('ol.TileStore.createOpenStreetMap');
+
+
+function testOpenStreetMap() {
+
+  var tileStore = ol.TileStore.createOpenStreetMap(8);
+  var tileGrid = tileStore.getTileGrid();
+
+  var coordinate =
+      new goog.math.Coordinate(829330.2064098881, 5933916.615134273);
+  var tileUrl;
+
+  var getTileCoordPart = function(tileUrl) {
+    return tileUrl.substr(32, tileUrl.length - 36);
+  };
+
+  tileUrl = tileStore.getTileCoordUrl(tileGrid.getTileCoord(0, coordinate));
+  assertEquals('0/0/0', getTileCoordPart(tileUrl));
+
+  tileUrl = tileStore.getTileCoordUrl(tileGrid.getTileCoord(1, coordinate));
+  assertEquals('1/1/0', getTileCoordPart(tileUrl));
+
+  tileUrl = tileStore.getTileCoordUrl(tileGrid.getTileCoord(2, coordinate));
+  assertEquals('2/2/1', getTileCoordPart(tileUrl));
+
+  tileUrl = tileStore.getTileCoordUrl(tileGrid.getTileCoord(3, coordinate));
+  assertEquals('3/4/2', getTileCoordPart(tileUrl));
+
+  tileUrl = tileStore.getTileCoordUrl(tileGrid.getTileCoord(4, coordinate));
+  assertEquals('4/8/5', getTileCoordPart(tileUrl));
+
+  tileUrl = tileStore.getTileCoordUrl(tileGrid.getTileCoord(5, coordinate));
+  assertEquals('5/16/11', getTileCoordPart(tileUrl));
+
+  tileUrl = tileStore.getTileCoordUrl(tileGrid.getTileCoord(6, coordinate));
+  assertEquals('6/33/22', getTileCoordPart(tileUrl));
+
+}

src/ol/tileurlfunction.js

@@ -44,3 +44,16 @@ ol.TileUrlFunction.createFromTemplates = function(templates) {
   return ol.TileUrlFunction.createFromTileUrlFunctions(
       goog.array.map(templates, ol.TileUrlFunction.createFromTemplate));
 };
+
+
+/**
+ * @param {function(ol.TileCoord): ol.TileCoord} transform Transform.
+ * @param {ol.TileUrlFunctionType} tileUrlFunction Tile URL function.
+ * @return {ol.TileUrlFunctionType} Tile URL function.
+ */
+ol.TileUrlFunction.withTileCoordTransform =
+    function(transform, tileUrlFunction) {
+  return function(tileCoord) {
+    return tileUrlFunction(transform(tileCoord));
+  };
+};

src/ol/tileurlfunction_test.js

@@ -9,6 +9,16 @@ function testCreateFromTemplate() {
 }
 
 
+function testWithTileCoordTransform() {
+  var tileUrl = ol.TileUrlFunction.withTileCoordTransform(
+      function(tileCoord) {
+        return new ol.TileCoord(tileCoord.z, tileCoord.x, -tileCoord.y);
+      },
+      ol.TileUrlFunction.createFromTemplate('{z}/{x}/{y}'));
+  assertEquals('3/2/1', tileUrl(new ol.TileCoord(3, 2, -1)));
+}
+
+
 function testCreateFromTileUrlFunctions() {
   var tileUrl = ol.TileUrlFunction.createFromTileUrlFunctions([
     ol.TileUrlFunction.createFromTemplate('a'),