Box Selection

Using a DragBox interaction to select features.

This example shows how to use a DragBox interaction to select features. Selected features are added to the feature overlay of a select interaction (ol.interaction.Select) for highlighting.

Use Ctrl+Drag (Command+Drag on Mac) to draw boxes.

Related API documentation:

Copy Edit

var vectorSource = new ol.source.Vector({
  url: 'https://openlayers.org/en/v4.6.4/examples/data/geojson/countries.geojson',
  format: new ol.format.GeoJSON()
});

var map = new ol.Map({
  layers: [
    new ol.layer.Tile({
      source: new ol.source.OSM()
    }),
    new ol.layer.Vector({
      source: vectorSource
    })
  ],
  target: 'map',
  view: new ol.View({
    center: [0, 0],
    zoom: 2
  })
});

// a normal select interaction to handle click
var select = new ol.interaction.Select();
map.addInteraction(select);

var selectedFeatures = select.getFeatures();

// a DragBox interaction used to select features by drawing boxes
var dragBox = new ol.interaction.DragBox({
  condition: ol.events.condition.platformModifierKeyOnly
});

map.addInteraction(dragBox);

dragBox.on('boxend', function() {
  // features that intersect the box are added to the collection of
  // selected features
  var extent = dragBox.getGeometry().getExtent();
  vectorSource.forEachFeatureIntersectingExtent(extent, function(feature) {
    selectedFeatures.push(feature);
  });
});

// clear selection when drawing a new box and when clicking on the map
dragBox.on('boxstart', function() {
  selectedFeatures.clear();
});

var infoBox = document.getElementById('info');

selectedFeatures.on(['add', 'remove'], function() {
  var names = selectedFeatures.getArray().map(function(feature) {
    return feature.get('name');
  });
  if (names.length > 0) {
    infoBox.innerHTML = names.join(', ');
  } else {
    infoBox.innerHTML = 'No countries selected';
  }
});

<!DOCTYPE html>
<html>
  <head>
    <title>Box Selection</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=""></script>
    <script src="https://openlayers.org/en/v4.6.4/build/ol.js"></script>
    <style>
      .ol-dragbox {
        background-color: rgba(255,255,255,0.4);
        border-color: rgba(100,150,0,1);
      }
    </style>
  </head>
  <body>
    <div id="map" class="map"></div>
    <div id="info">No countries selected</div>
    <script>
      var vectorSource = new ol.source.Vector({
        url: 'https://openlayers.org/en/v4.6.4/examples/data/geojson/countries.geojson',
        format: new ol.format.GeoJSON()
      });


      var map = new ol.Map({
        layers: [
          new ol.layer.Tile({
            source: new ol.source.OSM()
          }),
          new ol.layer.Vector({
            source: vectorSource
          })
        ],
        target: 'map',
        view: new ol.View({
          center: [0, 0],
          zoom: 2
        })
      });

      // a normal select interaction to handle click
      var select = new ol.interaction.Select();
      map.addInteraction(select);

      var selectedFeatures = select.getFeatures();

      // a DragBox interaction used to select features by drawing boxes
      var dragBox = new ol.interaction.DragBox({
        condition: ol.events.condition.platformModifierKeyOnly
      });

      map.addInteraction(dragBox);

      dragBox.on('boxend', function() {
        // features that intersect the box are added to the collection of
        // selected features
        var extent = dragBox.getGeometry().getExtent();
        vectorSource.forEachFeatureIntersectingExtent(extent, function(feature) {
          selectedFeatures.push(feature);
        });
      });

      // clear selection when drawing a new box and when clicking on the map
      dragBox.on('boxstart', function() {
        selectedFeatures.clear();
      });

      var infoBox = document.getElementById('info');

      selectedFeatures.on(['add', 'remove'], function() {
        var names = selectedFeatures.getArray().map(function(feature) {
          return feature.get('name');
        });
        if (names.length > 0) {
          infoBox.innerHTML = names.join(', ');
        } else {
          infoBox.innerHTML = 'No countries selected';
        }
      });
    </script>
  </body>
</html>