Fix render context utility functions and feature-move-animation example

examples/feature-move-animation.html

@@ -3,10 +3,10 @@ layout: example.html
 title: Marker Animation
 shortdesc: Demonstrates how to move a feature along a line.
 docs: >
-  This example shows how to use <b>postcompose</b> and <b>vectorContext</b> to
-  animate a (marker) feature along a line. In this example an encoded polyline
+  This example shows how to use <b>postrender</b> events and a <b>vector context</b> to
+  animate a marker feature along a line. In this example an encoded polyline
   is being used.
-tags: "animation, feature, postcompose, polyline"
+tags: "animation, feature, postrender, polyline"
 cloak:
   - key: As1HiMj1PvLPlqc_gtM7AqZfBL8ZL3VrjaS3zIb22Uvb9WKhuJObROC-qUpa81U5
     value: Your Bing Maps Key from http://www.bingmapsportal.com/ here

examples/feature-move-animation.js

@@ -7,6 +7,7 @@ import {Tile as TileLayer, Vector as VectorLayer} from '../src/ol/layer.js';
 import BingMaps from '../src/ol/source/BingMaps.js';
 import VectorSource from '../src/ol/source/Vector.js';
 import {Circle as CircleStyle, Fill, Icon, Stroke, Style} from '../src/ol/style.js';
+import {getVectorContext} from '../src/ol/render.js';
 
 // This long string is placed here due to jsFiddle limitations.
 // It is usually loaded with AJAX.
@@ -142,7 +143,7 @@ const map = new Map({
 });
 
 const moveFeature = function(event) {
-  const vectorContext = event.vectorContext;
+  const vectorContext = getVectorContext(event);
   const frameState = event.frameState;
 
   if (animating) {
@@ -176,7 +177,7 @@ function startAnimation() {
     geoMarker.setStyle(null);
     // just in case you pan somewhere else
     map.getView().setCenter(center);
-    map.on('postcompose', moveFeature);
+    vectorLayer.on('postrender', moveFeature);
     map.render();
   }
 }