Add new 'weight' option to ol.layer.Heatmap

src/objectliterals.jsdoc

@@ -595,6 +595,8 @@
  * @property {number|undefined} radius Radius size in pixels. Default is `8`.
  * @property {number|undefined} blur Blur size in pixels. Default is `15`.
  * @property {number|undefined} shadow Shadow size in pixels. Default is `250`.
+ * @property {string|function(ol.Feature):number|undefined} weight The feature attribute to use for the
+ *     weight or a function that returns a weight from a feature. Default is `weight`.
  * @property {number|undefined} minResolution The minimum resolution
  *      (inclusive) at which this layer will be visible.
  * @property {number|undefined} maxResolution The maximum resolution

src/ol/layer/heatmaplayer.js

@@ -55,8 +55,19 @@ ol.layer.Heatmap = function(opt_options) {
    */
   var styleCache = new Array(256);
 
+  var weight = goog.isDef(options.weight) ? options.weight : 'weight';
+  var weightFunction;
+  if (goog.isString(weight)) {
+    weightFunction = function(feature) {
+      return feature.get(weight);
+    };
+  } else {
+    weightFunction = weight;
+  }
+  goog.asserts.assert(goog.isFunction(weightFunction));
+
   this.setStyle(function(feature, resolution) {
-    var weight = feature.get('weight');
+    var weight = weightFunction(feature);
     var opacity = goog.isDef(weight) ? weight : 1;
     // cast to 8 bits
     var index = (255 * opacity) | 0;