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<title>OpenLayers Vector Behavior Example</title>
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<script src="../lib/OpenLayers.js"></script>
<script type="text/javascript">
var map;
function init(){
map = new OpenLayers.Map('map');
var wms = new OpenLayers.Layer.WMS(
"OpenLayers WMS", "http://vmap0.tiles.osgeo.org/wms/vmap0",
{layers: 'basic'}
);
var layer = new OpenLayers.Layer.Vector("POIs", {
strategies: [new OpenLayers.Strategy.BBOX({resFactor: 1.1})],
protocol: new OpenLayers.Protocol.HTTP({
url: "textfile.txt",
format: new OpenLayers.Format.Text()
})
});
map.addLayers([wms, layer]);
map.zoomToMaxExtent();
// Interaction; not needed for initial display.
selectControl = new OpenLayers.Control.SelectFeature(layer);
map.addControl(selectControl);
selectControl.activate();
layer.events.on({
'featureselected': onFeatureSelect,
'featureunselected': onFeatureUnselect
});
}
// Needed only for interaction, not for the display.
function onPopupClose(evt) {
// 'this' is the popup.
var feature = this.feature;
if (feature.layer) { // The feature is not destroyed
selectControl.unselect(feature);
} else { // After "moveend" or "refresh" events on POIs layer all
// features have been destroyed by the Strategy.BBOX
this.destroy();
}
}
function onFeatureSelect(evt) {
feature = evt.feature;
popup = new OpenLayers.Popup.FramedCloud("featurePopup",
feature.geometry.getBounds().getCenterLonLat(),
new OpenLayers.Size(100,100),
"<h2>"+feature.attributes.title + "</h2>" +
feature.attributes.description,
null, true, onPopupClose);
feature.popup = popup;
popup.feature = feature;
map.addPopup(popup, true);
}
function onFeatureUnselect(evt) {
feature = evt.feature;
if (feature.popup) {
popup.feature = null;
map.removePopup(feature.popup);
feature.popup.destroy();
feature.popup = null;
}
}
</script>
</head>
<body onload="init()">
<h1 id="title">Dynamic POIs via a Text Layer</h1>
<div id="tags">
poi, dynamic data, text, format, strategy, popup, select, selection
</div>
<p id="shortdesc">
Loading dynamic data from a text file.
</p>
<div id="map" class="smallmap"></div>
<div id="docs">
<p>The vector layer shown uses the BBOX strategy, the HTTP protocol,
and the Text format.
This setup appends "?bbox=west,south,east,north" to every
request. This allows you to configure the location as something
like 'textfile.php', and take the '?bbox=' parameter to select
data from a database or the like.</p>
<p>There is nothing about this example that limits it to text files;
you can do the same thing with KML, GeoJSON, etc.</p>
<p>This is an alternative to something like the <a href="http://wiki.openstreetmap.org/index.php/OpenLayers_Dynamic_POI">OpenStreetMap "Dynamic POI"</a> example. The Layer is a standard vector layer, and interaction can be
configured via the SelectFeature control, as you can see in the
latter half of the code, which allows you to open a popup when
a feature is selected.</p>
</div>
</body>
</html>
