Image Vector Layer

 

Example of an image vector layer.

This example uses ol.layer.Vector with renderMode: 'image'. This mode results in faster rendering during interaction and animations, at the cost of less accurate rendering.

<!DOCTYPE html>
<html>
  <head>
    <title>Image Vector Layer</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>
    <div id="info">&nbsp;</div>
    <script>
      var style = new ol.style.Style({
        fill: new ol.style.Fill({
          color: 'rgba(255, 255, 255, 0.6)'
        }),
        stroke: new ol.style.Stroke({
          color: '#319FD3',
          width: 1
        }),
        text: new ol.style.Text()
      });

      var map = new ol.Map({
        layers: [
          new ol.layer.Vector({
            renderMode: 'image',
            source: new ol.source.Vector({
              url: 'https://openlayers.org/en/v4.6.4/examples/data/geojson/countries.geojson',
              format: new ol.format.GeoJSON()
            }),
            style: function(feature) {
              style.getText().setText(feature.get('name'));
              return style;
            }
          })
        ],
        target: 'map',
        view: new ol.View({
          center: [0, 0],
          zoom: 1
        })
      });

      var featureOverlay = new ol.layer.Vector({
        source: new ol.source.Vector(),
        map: map,
        style: new ol.style.Style({
          stroke: new ol.style.Stroke({
            color: '#f00',
            width: 1
          }),
          fill: new ol.style.Fill({
            color: 'rgba(255,0,0,0.1)'
          })
        })
      });

      var highlight;
      var displayFeatureInfo = function(pixel) {

        var feature = map.forEachFeatureAtPixel(pixel, function(feature) {
          return feature;
        });

        var info = document.getElementById('info');
        if (feature) {
          info.innerHTML = feature.getId() + ': ' + feature.get('name');
        } else {
          info.innerHTML = '&nbsp;';
        }

        if (feature !== highlight) {
          if (highlight) {
            featureOverlay.getSource().removeFeature(highlight);
          }
          if (feature) {
            featureOverlay.getSource().addFeature(feature);
          }
          highlight = feature;
        }

      };

      map.on('pointermove', function(evt) {
        if (evt.dragging) {
          return;
        }
        var pixel = map.getEventPixel(evt.originalEvent);
        displayFeatureInfo(pixel);
      });

      map.on('click', function(evt) {
        displayFeatureInfo(evt.pixel);
      });
    </script>
  </body>
</html>