Edit

Custom Animation

Demonstrates how to animate features.

This example shows how to use postrender and vectorContext to animate features. Here we choose to do a flash animation each time a feature is added to the layer.

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index.html<!DOCTYPE html>
<html lang="en">
  <head>
    <title>Custom Animation</title>
    <!-- The line below is only needed for old environments like Internet Explorer and Android 4.x -->
    <script src="https://cdn.polyfill.io/v2/polyfill.min.js?features=requestAnimationFrame,Element.prototype.classList,URL"></script>
    <style>
      .map {
        width: 100%;
        height:400px;
      }
    </style>
  </head>
  <body>
    <div id="map" class="map"></div>
    <script src="index.js"></script>
  </body>
</html>
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index.jsimport 'ol/ol.css';
import Feature from 'ol/Feature';
import Map from 'ol/Map';
import {unByKey} from 'ol/Observable';
import View from 'ol/View';
import {easeOut} from 'ol/easing';
import Point from 'ol/geom/Point';
import {Tile as TileLayer, Vector as VectorLayer} from 'ol/layer';
import {fromLonLat} from 'ol/proj';
import {OSM, Vector as VectorSource} from 'ol/source';
import {Circle as CircleStyle, Stroke, Style} from 'ol/style';
import {getVectorContext} from 'ol/render';

var tileLayer = new TileLayer({
  source: new OSM({
    wrapX: false
  })
});

var map = new Map({
  layers: [tileLayer],
  target: 'map',
  view: new View({
    center: [0, 0],
    zoom: 1,
    multiWorld: true
  })
});

var source = new VectorSource({
  wrapX: false
});
var vector = new VectorLayer({
  source: source
});
map.addLayer(vector);

function addRandomFeature() {
  var x = Math.random() * 360 - 180;
  var y = Math.random() * 180 - 90;
  var geom = new Point(fromLonLat([x, y]));
  var feature = new Feature(geom);
  source.addFeature(feature);
}

var duration = 3000;
function flash(feature) {
  var start = new Date().getTime();
  var listenerKey = tileLayer.on('postrender', animate);

  function animate(event) {
    var vectorContext = getVectorContext(event);
    var frameState = event.frameState;
    var flashGeom = feature.getGeometry().clone();
    var elapsed = frameState.time - start;
    var elapsedRatio = elapsed / duration;
    // radius will be 5 at start and 30 at end.
    var radius = easeOut(elapsedRatio) * 25 + 5;
    var opacity = easeOut(1 - elapsedRatio);

    var style = new Style({
      image: new CircleStyle({
        radius: radius,
        stroke: new Stroke({
          color: 'rgba(255, 0, 0, ' + opacity + ')',
          width: 0.25 + opacity
        })
      })
    });

    vectorContext.setStyle(style);
    vectorContext.drawGeometry(flashGeom);
    if (elapsed > duration) {
      unByKey(listenerKey);
      return;
    }
    // tell OpenLayers to continue postrender animation
    map.render();
  }
}

source.on('addfeature', function(e) {
  flash(e.feature);
});

window.setInterval(addRandomFeature, 1000);
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package.json{
  "name": "feature-animation",
  "dependencies": {
    "ol": "6.1.1"
  },
  "devDependencies": {
    "parcel": "1.11.0"
  },
  "scripts": {
    "start": "parcel index.html",
    "build": "parcel build --experimental-scope-hoisting --public-url . index.html"
  }
}