goog.require('ol.Map');
goog.require('ol.View');
goog.require('ol.control');
goog.require('ol.format.GeoJSON');
goog.require('ol.layer.Tile');
goog.require('ol.layer.Vector');
goog.require('ol.source.OSM');
goog.require('ol.source.Vector');

var map = new ol.Map({
  layers: [
    new ol.layer.Tile({
      source: new ol.source.OSM()
    }),
    new ol.layer.Vector({
      source: new ol.source.Vector({
        url: 'data/geojson/countries.geojson',
        format: new ol.format.GeoJSON()
      })
    })
  ],
  target: 'map',
  controls: ol.control.defaults({
    attributionOptions: /** @type {olx.control.AttributionOptions} */ ({
      collapsible: false
    })
  }),
  view: new ol.View({
    center: [0, 0],
    zoom: 2
  })
});

var exportPNGElement = document.getElementById('export-png');

if ('download' in exportPNGElement) {
  exportPNGElement.addEventListener('click', function() {
    map.once('postcompose', function(event) {
      var canvas = event.context.canvas;
      exportPNGElement.href = canvas.toDataURL('image/png');
    });
    map.renderSync();
  }, false);
} else {
  var info = document.getElementById('no-download');
  /**
   * display error message
   */
  info.style.display = '';
}