[OpenLayers-Users] VectorLayer destroyFeatures doesn't work properly?

Tue Apr 6 15:42:13 EDT 2010

I have a vectorLayer, polygonLayer, which I am calling
destroyFeatures(polygonLayer.features) on. I can confirm that after calling
it, the features go away in the polygonLayer.features variable. However, the
features (polygons drawn by the DrawFeatures controller as per the example
found at:
http://openlayers.org/dev/examples/regular-polygons.html
http://openlayers.org/dev/examples/regular-polygons.html 
) don't actually go away on screen (they are still drawn on the map).

I thought maybe calling redraw() on the vectorLayer would help, but no dice.
Even though I have only one feature in the layers' array, I am seeing
several circles on screen.

>From the API, I got the impression that the features would be both erased
AND removed from the array. Was I wrong? How can I get the features to go
away?

Background:  I only want one polygon on screen at a time, thus when the
event "beforeaddingfeature" is called, I clear all existing features, and
then let the current feature be added like normal. 

~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
Code:

<html>
<head>
<h1> Select Blackout Area </h1>
	<script type="text/javascript" src="javascripts/jquery-1.3.2.js"></script>
	<script type="text/javascript"
src="javascripts/jquery.timers-1.2.js"></script>

	<!-- bring in the OpenLayers javascript library
		 (here we bring it from the remote site, but you could
		 easily serve up this javascript yourself) -->
	<script src="http://www.openlayers.org/api/OpenLayers.js"></script>
		<script src="/javascripts/OpenStreetMap.js"></script>

	<script type="text/javascript">
	       // making this a global variable so that it is accessible for
        // debugging/inspecting in Firebug
        var map, polygonControl, polygonLayer;
        var bounds = new OpenLayers.Bounds(-125, 25, -65, 50);

        function init(){

  var navControl = new OpenLayers.Control.Navigation();
           			map = new OpenLayers.Map ("map", {
				controls:[
					navControl,
					//new OpenLayers.Control.PanZoomBar(),
					//new OpenLayers.Control.LayerSwitcher(),
					new OpenLayers.Control.Attribution()],
				numZoomLevels: 10,
				//restrictedExtent: bounds.clone().transform(EPSG4326, EPSG900913),

restrictedExtent: bounds.clone().transform(
        new OpenLayers.Projection("EPSG:4326"),
        new OpenLayers.Projection("EPSG:900913")),

maxExtent: bounds.clone().transform(
        new OpenLayers.Projection("EPSG:4326"),
        new OpenLayers.Projection("EPSG:900913")),
				maxResolution: "auto",
				units: 'm',
				projection: new OpenLayers.Projection("EPSG:900913"),
				displayProjection: new OpenLayers.Projection("EPSG:4326")
			} );

           //actually draws the map 
            layerMapnik = new OpenLayers.Layer.OSM.Mapnik("Mapnik", {
			displayOutsideMaxExtent: false,
			wrapDateLine: true
			//numZoomLevels: 4
			});
		    polygonLayer = new OpenLayers.Layer.Vector("Polygon Layer");
			map.addLayer(layerMapnik);
			map.addLayer(polygonLayer);
			map.addControl(new OpenLayers.Control.MousePosition());
            map.addControl(new OpenLayers.Control.LayerSwitcher());
            var polyOptions = {sides: 40};
            polygonControl = new
OpenLayers.Control.DrawFeature(polygonLayer,

OpenLayers.Handler.RegularPolygon,
                                            {handlerOptions: polyOptions});
           map.setCenter(new OpenLayers.LonLat(0, 0), 3);
           //polygonControl.activate();

            map.addControl(polygonControl);
            map.zoomToMaxExtent();
            var feature;
            polygonLayer.events.register("beforefeatureadded", feature,
function(evt){
            //only one circle at a time
            clearCircles();
            });//end attempt at events registration
        }//end init

                function setSize(fraction) {
            var radius = fraction * map.getExtent().getHeight();
            polygonControl.handler.setOptions({radius: radius,
                                               angle: 0});

        }//end setSize

        function clearCircles(){
        console.log("Clearing existing circles");
        console.log(polygonLayer.features.length);
        polygonLayer.destroyFeatures(polygonLayer.features);
        polygonLayer.redraw();
        }//end clearCircles
    </script>

	</script>

	</head>

	<body onload="init()">
	<ul id="controls">Map Controls

                <input type="radio" name="type"
                       value="none" id="noneToggle"
                       onclick="polygonControl.deactivate()"
                       checked="checked" />
                <label for="noneToggle">navigate</label>

                <input type="radio" name="type"
                       value="polygon" id="polygonToggle"
                       onclick="polygonControl.activate()" />
                <label for="polygonToggle">draw polygon</label>

        </ul>
	  <div id="map" class="small_map"></div>

	</body>

	</html>
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