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first calls unselect on the selectfeaturecontrol. However, this fails if the feature in question is no longer in the map -- for example, if you zoom in or otherwise change positions. (The selected feature no longer exists, so you call close on a feature which no longer has a layer object.) This change to the examples by Jorix fixes this behavior in the example. Note that many people use similar functionalities in their code, so this likely means that what we *should* do is armor unselect() against being called with a feature with a null layer, but that involves a longer discussion -- do we still fire onUnselect? Do we still fire the unselect events? is there other cleanup we need to do? etc. -- so this is changing the example to demonstrate one way to armor application code against the problem. Thanks to jorix for the suggestion on the example fix. (See #3046) (See #2515) git-svn-id: http://svn.openlayers.org/trunk/openlayers@11707 dc9f47b5-9b13-0410-9fdd-eb0c1a62fdaf
102 lines
4.6 KiB
HTML
102 lines
4.6 KiB
HTML
<html xmlns="http://www.w3.org/1999/xhtml">
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<head>
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<meta name="viewport" content="width=device-width; initial-scale=1.0; maximum-scale=1.0; user-scalable=0;" />
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<meta name="apple-mobile-web-app-capable" content="yes" />
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<title>OpenLayers Vector Behavior Example</title>
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<link rel="stylesheet" href="../theme/default/style.css" type="text/css" />
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<link rel="stylesheet" href="style.css" type="text/css" />
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<script src="../lib/OpenLayers.js"></script>
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<script type="text/javascript">
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var map;
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function init(){
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map = new OpenLayers.Map('map');
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var wms = new OpenLayers.Layer.WMS(
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"OpenLayers WMS", "http://vmap0.tiles.osgeo.org/wms/vmap0",
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{layers: 'basic'}
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);
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var layer = new OpenLayers.Layer.Vector("POIs", {
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strategies: [new OpenLayers.Strategy.BBOX({resFactor: 1.1})],
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protocol: new OpenLayers.Protocol.HTTP({
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url: "textfile.txt",
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format: new OpenLayers.Format.Text()
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})
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});
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map.addLayers([wms, layer]);
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map.zoomToMaxExtent();
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// Interaction; not needed for initial display.
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selectControl = new OpenLayers.Control.SelectFeature(layer);
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map.addControl(selectControl);
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selectControl.activate();
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layer.events.on({
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'featureselected': onFeatureSelect,
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'featureunselected': onFeatureUnselect
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});
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}
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// Needed only for interaction, not for the display.
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function onPopupClose(evt) {
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// 'this' is the popup.
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var feature = this.feature;
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if (feature.layer) { // The feature is not destroyed
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selectControl.unselect(feature);
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} else { // After "moveend" or "refresh" events on POIs layer all
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// features have been destroyed by the Strategy.BBOX
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this.destroy();
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}
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}
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function onFeatureSelect(evt) {
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feature = evt.feature;
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popup = new OpenLayers.Popup.FramedCloud("featurePopup",
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feature.geometry.getBounds().getCenterLonLat(),
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new OpenLayers.Size(100,100),
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"<h2>"+feature.attributes.title + "</h2>" +
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feature.attributes.description,
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null, true, onPopupClose);
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feature.popup = popup;
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popup.feature = feature;
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map.addPopup(popup, true);
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}
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function onFeatureUnselect(evt) {
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feature = evt.feature;
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if (feature.popup) {
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popup.feature = null;
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map.removePopup(feature.popup);
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feature.popup.destroy();
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feature.popup = null;
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}
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}
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</script>
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</head>
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<body onload="init()">
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<h1 id="title">Dynamic POIs via a Text Layer</h1>
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<div id="tags">
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poi, dynamic data, text, format, strategy, popup, select, selection
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</div>
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<p id="shortdesc">
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Loading dynamic data from a text file.
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</p>
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<div id="map" class="smallmap"></div>
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<div id="docs">
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The vector layer shown uses the BBOX strategy, the HTTP protocol,
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and the Text format.
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This setup appends "?bbox=west,south,east,north" to every
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request. This allows you to configure the location as something
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like 'textfile.php', and take the '?bbox=' parameter to select
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data from a database or the like.
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<br /><br />
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There is nothing about this example that limits it to text files;
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you can do the same thing with KML, GeoJSON, etc.
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<br /><br />
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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
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configured via the SelectFeature control, as you can see in the
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latter half of the code, which allows you to open a popup when
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a feature is selected.
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</div>
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</body>
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</html>
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