Fix vector tile rotation on HiDPI devices

src/ol/source/tile.js

@@ -242,10 +242,14 @@ ol.source.Tile.prototype.getTileCacheForProjection = function(projection) {
 
 
 /**
- * @param {number} pixelRatio Pixel ratio.
+ * Get the tile pixel ratio for this source. Subclasses may override this
+ * method, which is meant to return a supported pixel ratio that matches the
+ * provided `opt_pixelRatio` as close as possible. When no `opt_pixelRatio` is
+ * provided, it is meant to return `this.tilePixelRatio_`.
+ * @param {number=} opt_pixelRatio Pixel ratio.
  * @return {number} Tile pixel ratio.
  */
-ol.source.Tile.prototype.getTilePixelRatio = function(pixelRatio) {
+ol.source.Tile.prototype.getTilePixelRatio = function(opt_pixelRatio) {
   return this.tilePixelRatio_;
 };
 

src/ol/source/tilearcgisrest.js

@@ -121,7 +121,7 @@ ol.source.TileArcGISRest.prototype.getRequestUrl_ = function(tileCoord, tileSize
  * @inheritDoc
  */
 ol.source.TileArcGISRest.prototype.getTilePixelRatio = function(pixelRatio) {
-  return pixelRatio;
+  return /** @type {number} */ (pixelRatio);
 };
 
 

src/ol/source/tilewms.js

@@ -271,7 +271,8 @@ ol.source.TileWMS.prototype.getRequestUrl_ = function(tileCoord, tileSize, tileE
  * @inheritDoc
  */
 ol.source.TileWMS.prototype.getTilePixelRatio = function(pixelRatio) {
-  return (!this.hidpi_ || this.serverType_ === undefined) ? 1 : pixelRatio;
+  return (!this.hidpi_ || this.serverType_ === undefined) ? 1 :
+      /** @type {number} */ (pixelRatio);
 };
 
 

src/ol/source/vectortile.js

@@ -104,12 +104,22 @@ ol.source.VectorTile.prototype.getTile = function(z, x, y, pixelRatio, projectio
 };
 
 
+/**
+ * @inheritDoc
+ */
+ol.source.VectorTile.prototype.getTilePixelRatio = function(opt_pixelRatio) {
+  return opt_pixelRatio == undefined ?
+      ol.source.UrlTile.prototype.getTilePixelRatio.call(this, opt_pixelRatio) :
+      opt_pixelRatio;
+};
+
+
 /**
  * @inheritDoc
  */
 ol.source.VectorTile.prototype.getTilePixelSize = function(z, pixelRatio, projection) {
   var tileSize = ol.size.toSize(this.tileGrid.getTileSize(z));
-  return [tileSize[0] * pixelRatio, tileSize[1] * pixelRatio];
+  return [Math.round(tileSize[0] * pixelRatio), Math.round(tileSize[1] * pixelRatio)];
 };