Vector Image Layer

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Vector Image Layer

Example of rendering vector data as an image layer.

This example uses ol/layer/VectorImage for faster rendering during interaction and animations, at the cost of less accurate rendering.

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index.html<!DOCTYPE html>
<html lang="en">
  <head>
    <title>Vector Image Layer</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>
    <div id="info">&nbsp;</div>
    <script src="index.js"></script>
  </body>
</html>

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index.jsimport 'ol/ol.css';
import Map from 'ol/Map';
import View from 'ol/View';
import GeoJSON from 'ol/format/GeoJSON';
import VectorImageLayer from 'ol/layer/VectorImage';
import VectorLayer from 'ol/layer/Vector';
import VectorSource from 'ol/source/Vector';
import {Fill, Stroke, Style, Text} from 'ol/style';


var style = new Style({
  fill: new Fill({
    color: 'rgba(255, 255, 255, 0.6)'
  }),
  stroke: new Stroke({
    color: '#319FD3',
    width: 1
  }),
  text: new Text()
});

var map = new Map({
  layers: [
    new VectorImageLayer({
      imageRatio: 2,
      source: new VectorSource({
        url: 'data/geojson/countries.geojson',
        format: new GeoJSON()
      }),
      style: function(feature) {
        style.getText().setText(feature.get('name'));
        return style;
      }
    })
  ],
  target: 'map',
  view: new View({
    center: [0, 0],
    zoom: 1
  })
});

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

var highlight;
var displayFeatureInfo = function(pixel) {

  map.getLayers().item(0).getFeatures(pixel).then(function(features) {
    var feature = features.length > 0 ? features[0] : undefined;

    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) {
    displayFeatureInfo(evt.pixel);
  }
});

map.on('click', function(evt) {
  displayFeatureInfo(evt.pixel);
});

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package.json{
  "name": "image-vector-layer",
  "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"
  }
}