Add gutter option to ol.source.TileWMS

src/objectliterals.jsdoc

@@ -703,6 +703,15 @@
  * @property {ol.Extent|undefined} extent Extent.
  * @property {ol.source.WMSGetFeatureInfoOptions|undefined} getFeatureInfoOptions
  *     Options for GetFeatureInfo.
+ * @property {number|undefined} gutter The size in pixels of the
+ *     gutter around image tiles to ignore.  By setting this property to a
+ *     non-zero value, images will be requested that are wider and taller than
+ *     the tile size by a value of `2 x gutter`.  Defaults to zero.  Using a
+ *     non-zero value allows artifacts of rendering at tile edges to be ignored.  If
+ *     you control the WMS service it is recommended to address "artifacts at tile
+ *     edges" issues by properly configuring the WMS service. For example, MapServer
+ *     has a `tile_map_edge_buffer` configuration parameter for this. See
+ *     http://mapserver.org/output/tile_mode.html.
  * @property {string|undefined} logo Logo.
  * @property {ol.tilegrid.TileGrid|undefined} tileGrid Tile grid.
  * @property {number|undefined} maxZoom Maximum zoom.

src/ol/source/tilewmssource.js

@@ -35,6 +35,12 @@ ol.source.TileWMS = function(options) {
     urls = ol.TileUrlFunction.expandUrl(options.url);
   }
 
+  /**
+   * @private
+   * @type {number}
+   */
+  this.gutter_ = goog.isDef(options.gutter) ? options.gutter : 0;
+
   /**
    * @private
    * @type {Object}
@@ -117,6 +123,14 @@ ol.source.TileWMS = function(options) {
 goog.inherits(ol.source.TileWMS, ol.source.TileImage);
 
 
+/**
+ * @inheritDoc
+ */
+ol.source.TileWMS.prototype.getGutter = function() {
+  return this.gutter_;
+};
+
+
 /**
  * @inheritDoc
  */