Extent interaction example

examples/extent-interaction.html

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+---
+layout: example.html
+title: Extent Interaction
+shortdesc: Using an Extent interaction to draw an extent.
+docs: >
+  <p>This example shows how to use an <code>Extent</code> interaction to draw a modifiable extent.</p>
+  <p>Use <code>Shift+Drag</code> to draw an extent. 
+    <code>Shift+Drag</code> on the corners or edges of the extent to resize it. <code>Shift+Click</code> off the extent to remove it.
+  </p>
+tags: "Extent, interaction, box"
+---
+<div id="map" class="map"></div>

examples/extent-interaction.js

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+goog.require('ol.Map');
+goog.require('ol.View');
+goog.require('ol.events.condition');
+goog.require('ol.format.GeoJSON');
+goog.require('ol.interaction.Extent');
+goog.require('ol.layer.Tile');
+goog.require('ol.layer.Vector');
+goog.require('ol.source.OSM');
+goog.require('ol.source.Vector');
+
+var vectorSource = new ol.source.Vector({
+  url: '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
+    })
+  ],
+  renderer: 'canvas',
+  target: 'map',
+  view: new ol.View({
+    center: [0, 0],
+    zoom: 2
+  })
+});
+
+var extent = new ol.interaction.Extent({
+  condition: ol.events.condition.platformModifierKeyOnly
+});
+map.addInteraction(extent);
+extent.setActive(false);
+
+//Enable interaction by holding shift
+this.addEventListener('keydown', function(event) {
+  if (event.keyCode == 16) {
+    extent.setActive(true);
+  }
+});
+this.addEventListener('keyup', function(event) {
+  if (event.keyCode == 16) {
+    extent.setActive(false);
+  }
+});