Earthquakes in KML

Demonstrates the use of a Shape symbolizer to render earthquake locations.

This example parses a KML file and renders the features as a vector layer. The layer is given a style that renders earthquake locations with a size relative to their magnitude.

KML, vector, style, tooltip
<!DOCTYPE html>
<html>
<head>
<title>Earthquakes in KML</title>
<script src="https://code.jquery.com/jquery-1.11.2.min.js"></script>
<link rel="stylesheet" href="https://maxcdn.bootstrapcdn.com/bootstrap/3.3.5/css/bootstrap.min.css">
<script src="https://maxcdn.bootstrapcdn.com/bootstrap/3.3.5/js/bootstrap.min.js"></script>
<link rel="stylesheet" href="http://openlayers.org/en/v3.9.0/css/ol.css" type="text/css">
<script src="http://openlayers.org/en/v3.9.0/build/ol.js"></script>

<style>
#map {
  position: relative;
}
#info {
  position: absolute;
  height: 1px;
  width: 1px;
  z-index: 100;
}
.tooltip.in {
  opacity: 1;
  filter: alpha(opacity=100);
}
.tooltip.top .tooltip-arrow {
  border-top-color: white;
}
.tooltip-inner {
  border: 2px solid white;
}

</style>
</head>
<body>
<div class="container-fluid">

<div class="row-fluid">
  <div class="span12">
    <div id="map" class="map"><div id="info"></div></div>
  </div>
</div>

</div>
<script>
var styleCache = {};
var styleFunction = function(feature, resolution) {
  // 2012_Earthquakes_Mag5.kml stores the magnitude of each earthquake in a
  // standards-violating <magnitude> tag in each Placemark.  We extract it from
  // the Placemark's name instead.
  var name = feature.get('name');
  var magnitude = parseFloat(name.substr(2));
  var radius = 5 + 20 * (magnitude - 5);
  var style = styleCache[radius];
  if (!style) {
    style = [new ol.style.Style({
      image: new ol.style.Circle({
        radius: radius,
        fill: new ol.style.Fill({
          color: 'rgba(255, 153, 0, 0.4)'
        }),
        stroke: new ol.style.Stroke({
          color: 'rgba(255, 204, 0, 0.2)',
          width: 1
        })
      })
    })];
    styleCache[radius] = style;
  }
  return style;
};

var vector = new ol.layer.Vector({
  source: new ol.source.Vector({
    url: 'data/kml/2012_Earthquakes_Mag5.kml',
    format: new ol.format.KML({
      extractStyles: false
    })
  }),
  style: styleFunction
});

var raster = new ol.layer.Tile({
  source: new ol.source.Stamen({
    layer: 'toner'
  })
});

var map = new ol.Map({
  layers: [raster, vector],
  target: 'map',
  view: new ol.View({
    center: [0, 0],
    zoom: 2
  })
});

var info = $('#info');
info.tooltip({
  animation: false,
  trigger: 'manual'
});

var displayFeatureInfo = function(pixel) {
  info.css({
    left: pixel[0] + 'px',
    top: (pixel[1] - 15) + 'px'
  });
  var feature = map.forEachFeatureAtPixel(pixel, function(feature, layer) {
    return feature;
  });
  if (feature) {
    info.tooltip('hide')
        .attr('data-original-title', feature.get('name'))
        .tooltip('fixTitle')
        .tooltip('show');
  } else {
    info.tooltip('hide');
  }
};

map.on('pointermove', function(evt) {
  if (evt.dragging) {
    info.tooltip('hide');
    return;
  }
  displayFeatureInfo(map.getEventPixel(evt.originalEvent));
});

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

</script>
</body>
</html>