Marker Animation

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var route = /** @type {ol.geom.LineString} */ (new ol.format.Polyline({
  factor: 1e6
}).readGeometry(polyline, {
  dataProjection: 'EPSG:4326',
  featureProjection: 'EPSG:3857'
}));

var routeCoords = route.getCoordinates();
var routeLength = routeCoords.length;

var styles = {
  'route': new ol.style.Style({
    stroke: new ol.style.Stroke({
      width: 6, color: [237, 212, 0, 0.8]
    })
  }),
  'icon': new ol.style.Style({
    image: new ol.style.Icon({
      anchor: [0.5, 1],
      src: 'https://openlayers.org/en/v4.6.4/examples/data/icon.png'
    })
  }),
  'geoMarker': new ol.style.Style({
    image: new ol.style.Circle({
      radius: 7,
      snapToPixel: false,
      fill: new ol.style.Fill({color: 'black'}),
      stroke: new ol.style.Stroke({
        color: 'white', width: 2
      })
    })
  })
};

var animating = false;
var speed, now;
var speedInput = document.getElementById('speed');
var startButton = document.getElementById('start-animation');

var center = [-5639523.95, -3501274.52];
var map = new ol.Map({
  target: document.getElementById('map'),
  loadTilesWhileAnimating: true,
  view: new ol.View({
    center: center,
    zoom: 10,
    minZoom: 2,
    maxZoom: 19
  }),
  layers: [
    new ol.layer.Tile({
      source: new ol.source.BingMaps({
        imagerySet: 'AerialWithLabels',
        key: 'Your Bing Maps Key from http://www.bingmapsportal.com/ here'
      })
    }),
    vectorLayer
  ]
});

var moveFeature = function(event) {
  var vectorContext = event.vectorContext;
  var frameState = event.frameState;

if (animating) {
    var elapsedTime = frameState.time - now;
    // here the trick to increase speed is to jump some indexes
    // on lineString coordinates
    var index = Math.round(speed * elapsedTime / 1000);

if (index >= routeLength) {
      stopAnimation(true);
      return;
    }

var currentPoint = new ol.geom.Point(routeCoords[index]);
    var feature = new ol.Feature(currentPoint);
    vectorContext.drawFeature(feature, styles.geoMarker);
  }
  // tell OpenLayers to continue the postcompose animation
  map.render();
};

/**
 * @param {boolean} ended end of animation.
 */
function stopAnimation(ended) {
  animating = false;
  startButton.textContent = 'Start Animation';

// if animation cancelled set the marker at the beginning
  var coord = ended ? routeCoords[routeLength - 1] : routeCoords[0];
  /** @type {ol.geom.Point} */ (geoMarker.getGeometry())
      .setCoordinates(coord);
  //remove listener
  map.un('postcompose', moveFeature);
}

startButton.addEventListener('click', startAnimation, false);

<!DOCTYPE html>
<html>
  <head>
    <title>Marker Animation</title>
    <link rel="stylesheet" href="https://openlayers.org/en/v4.6.4/css/ol.css" type="text/css">
    <!-- 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>
    <script src="https://openlayers.org/en/v4.6.4/build/ol.js"></script>
  </head>
  <body>
    <div id="map" class="map"></div>
    <label for="speed">
      speed:&nbsp;
      <input id="speed" type="range" min="10" max="999" step="10" value="60">
    </label>
    <button id="start-animation">Start Animation</button>
    <script>
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      ].join('');

      var route = /** @type {ol.geom.LineString} */ (new ol.format.Polyline({
        factor: 1e6
      }).readGeometry(polyline, {
        dataProjection: 'EPSG:4326',
        featureProjection: 'EPSG:3857'
      }));

      var routeCoords = route.getCoordinates();
      var routeLength = routeCoords.length;

      var routeFeature = new ol.Feature({
        type: 'route',
        geometry: route
      });
      var geoMarker = new ol.Feature({
        type: 'geoMarker',
        geometry: new ol.geom.Point(routeCoords[0])
      });
      var startMarker = new ol.Feature({
        type: 'icon',
        geometry: new ol.geom.Point(routeCoords[0])
      });
      var endMarker = new ol.Feature({
        type: 'icon',
        geometry: new ol.geom.Point(routeCoords[routeLength - 1])
      });

      var styles = {
        'route': new ol.style.Style({
          stroke: new ol.style.Stroke({
            width: 6, color: [237, 212, 0, 0.8]
          })
        }),
        'icon': new ol.style.Style({
          image: new ol.style.Icon({
            anchor: [0.5, 1],
            src: 'https://openlayers.org/en/v4.6.4/examples/data/icon.png'
          })
        }),
        'geoMarker': new ol.style.Style({
          image: new ol.style.Circle({
            radius: 7,
            snapToPixel: false,
            fill: new ol.style.Fill({color: 'black'}),
            stroke: new ol.style.Stroke({
              color: 'white', width: 2
            })
          })
        })
      };

      var animating = false;
      var speed, now;
      var speedInput = document.getElementById('speed');
      var startButton = document.getElementById('start-animation');

      var vectorLayer = new ol.layer.Vector({
        source: new ol.source.Vector({
          features: [routeFeature, geoMarker, startMarker, endMarker]
        }),
        style: function(feature) {
          // hide geoMarker if animation is active
          if (animating && feature.get('type') === 'geoMarker') {
            return null;
          }
          return styles[feature.get('type')];
        }
      });

      var center = [-5639523.95, -3501274.52];
      var map = new ol.Map({
        target: document.getElementById('map'),
        loadTilesWhileAnimating: true,
        view: new ol.View({
          center: center,
          zoom: 10,
          minZoom: 2,
          maxZoom: 19
        }),
        layers: [
          new ol.layer.Tile({
            source: new ol.source.BingMaps({
              imagerySet: 'AerialWithLabels',
              key: 'Your Bing Maps Key from http://www.bingmapsportal.com/ here'
            })
          }),
          vectorLayer
        ]
      });

      var moveFeature = function(event) {
        var vectorContext = event.vectorContext;
        var frameState = event.frameState;

        if (animating) {
          var elapsedTime = frameState.time - now;
          // here the trick to increase speed is to jump some indexes
          // on lineString coordinates
          var index = Math.round(speed * elapsedTime / 1000);

          if (index >= routeLength) {
            stopAnimation(true);
            return;
          }

          var currentPoint = new ol.geom.Point(routeCoords[index]);
          var feature = new ol.Feature(currentPoint);
          vectorContext.drawFeature(feature, styles.geoMarker);
        }
        // tell OpenLayers to continue the postcompose animation
        map.render();
      };

      function startAnimation() {
        if (animating) {
          stopAnimation(false);
        } else {
          animating = true;
          now = new Date().getTime();
          speed = speedInput.value;
          startButton.textContent = 'Cancel Animation';
          // hide geoMarker
          geoMarker.setStyle(null);
          // just in case you pan somewhere else
          map.getView().setCenter(center);
          map.on('postcompose', moveFeature);
          map.render();
        }
      }


      /**
       * @param {boolean} ended end of animation.
       */
      function stopAnimation(ended) {
        animating = false;
        startButton.textContent = 'Start Animation';

        // if animation cancelled set the marker at the beginning
        var coord = ended ? routeCoords[routeLength - 1] : routeCoords[0];
        /** @type {ol.geom.Point} */ (geoMarker.getGeometry())
            .setCoordinates(coord);
        //remove listener
        map.un('postcompose', moveFeature);
      }

      startButton.addEventListener('click', startAnimation, false);
    </script>
  </body>
</html>