Merge pull request #1381 from twpayne/vector-api-feature-style-function

[vector-api] Per-feature styleFunction

src/ol/renderer/canvas/canvasvectorlayerrenderer.js

@@ -6,6 +6,7 @@ goog.require('goog.events.EventType');
 goog.require('goog.functions');
 goog.require('ol.ViewHint');
 goog.require('ol.extent');
+goog.require('ol.layer.Vector');
 goog.require('ol.render.canvas.ReplayGroup');
 goog.require('ol.renderer.canvas.Layer');
 goog.require('ol.renderer.vector');
@@ -194,6 +195,9 @@ ol.renderer.canvas.VectorLayer.prototype.prepareFrame =
   this.dirty_ = false;
 
   var styleFunction = vectorLayer.getStyleFunction();
+  if (!goog.isDef(styleFunction)) {
+    styleFunction = ol.layer.Vector.defaultStyleFunction;
+  }
   var replayGroup = new ol.render.canvas.ReplayGroup();
   vectorSource.forEachFeatureInExtent(extent,
       /**
@@ -227,6 +231,10 @@ ol.renderer.canvas.VectorLayer.prototype.renderFeature =
     function(feature, resolution, styleFunction, replayGroup) {
   var loading = false;
   var styles = styleFunction(feature, resolution);
+  // FIXME if styles is null, should we use the default style?
+  if (!goog.isDefAndNotNull(styles)) {
+    return false;
+  }
   // simplify to a tolerance of half a CSS pixel
   var squaredTolerance = resolution * resolution / 4;
   var i, ii, style, imageStyle, imageState;