Hi Paul,
from what I know about OpenLayers your code is what I'm looking for, but I
can't make the event working. What is interesting is that if I change what is
with red it deactivate cluster strategy no matter the zoom level.
map.events.register("move", null, function() { // #2, #3 respond to map extent
change
// disable cluster when zoom greater than threshold
if (map.getZoom() < clusterMaxZoom) { // #2.1 how to read current zoom
clusterStrategy.deactivate(); // #2.2 how to disable cluster
strategy
} else {
clusterStrategy.activate();
}
});
Help me please.
Here is my code:
....................................................................
<html>
<head>
<title>OpenLayers Test</title>
<script type="text/javascript" src="js/OpenLayers.js"></script>
<script defer="defer" type="text/javascript">
function init(){
// styles for cluster strategy
var style = new OpenLayers.Style({
fillColor: "${fill_color}",
fillOpacity: 0.4,
pointRadius: "${radius}",
strokeColor: "${stroke_color}",
strokeOpacity: 1,
strokeWidth: 1
},
{
context: {
radius: function(feature) {
var pix = 8;
if(feature.cluster) {
pix = Math.min(feature.attributes.count, 11) +
8;
}
return pix;
},
fill_color: function(feature) {
if(feature.cluster) {
maxImportance = 0;
for(var c = 0; c < feature.cluster.length;
c++) {
i =
feature.cluster[c].attributes.importance;
if(i > maxImportance) {
maxImportance = i;
mainFeature = c;
}
}
feature.attributes.fillColor =
feature.cluster[mainFeature].attributes.fillColor;
}
return feature.attributes.fillColor;
},
stroke_color: function(feature) {
if(feature.cluster) {
maxImportance = 0;
for(var c = 0; c < feature.cluster.length;
c++) {
i =
feature.cluster[c].attributes.importance;
if(i > maxImportance) {
maxImportance = i;
mainFeature = c;
}
}
feature.attributes.strokeColor =
feature.cluster[mainFeature].attributes.strokeColor;
}
return feature.attributes.strokeColor;
}
}
});
/* Creating the Map Viewer */
/*In order to create the viewer, you must first create a map. The
OpenLayers.Map constructor requires one argument: This argument must either be
an HTML Element, or the ID of an HTML element. This is the element in which the
map will be placed.*/
var map = new OpenLayers.Map("map", {
controls: [
new OpenLayers.Control.Navigation(),
new OpenLayers.Control.PanPanel(),
new OpenLayers.Control.ZoomPanel(),
new OpenLayers.Control.LayerSwitcher() /* Open the switch
layers panel */
],
maxResolution: 'auto',
numZoomLevels: 6 // maximum zoom
});
/*Map Constructor*/
/* The next step to creating a viewer is to add a basic layer to the
Map. */
var basicMapLayer = new OpenLayers.Layer.Image(
"Map Image",
"images/maps/MapImage.jpg",
new OpenLayers.Bounds(0, 0, 510, 510),
new OpenLayers.Size(510, 510)
);
/* Adding an Multipoint Vector Layer with cluster strategy */
var clusterStrategy = new OpenLayers.Strategy.Cluster({distance: 20});
var monuments = new OpenLayers.Layer.Vector("Monuments", {
strategies: [clusterStrategy],
styleMap: new OpenLayers.StyleMap({"default": style})
});
// cluster threshold
var clusterMaxZoom = 2; // maximum zoom is 6
map.events.register("move", null, function() { // #2, #3 respond to map
extent change
// disable cluster when zoom greater than threshold
if (map.getZoom() > clusterMaxZoom) { // #2.1 how to read current
zoom
clusterStrategy.deactivate(); // #2.2 how to disable cluster
strategy
} else {
clusterStrategy.activate();
}
});
var point_1 = new OpenLayers.Geometry.Point(270, 205);
var point_1_Feature = new OpenLayers.Feature.Vector(point_1);
point_1_Feature.attributes = {
strokeColor: "#ffffff",
fillColor: "#ffffff",
importance: 9
}
var point_2 = new OpenLayers.Geometry.Point(263, 201);
var point_2_Feature = new OpenLayers.Feature.Vector(point_2);
point_2_Feature.attributes = {
strokeColor: "blue",
fillColor: "blue",
importance: 3
}
var point_3 = new OpenLayers.Geometry.Point(260, 202);
var point_3_Feature = new OpenLayers.Feature.Vector(point_3);
point_3_Feature.attributes = {
strokeColor: "yellow",
fillColor: "yellow",
importance: 5
}
var point_4 = new OpenLayers.Geometry.Point(261, 202);
var point_4_Feature = new OpenLayers.Feature.Vector(point_4);
point_4_Feature.attributes = {
strokeColor: "yellow",
fillColor: "yellow",
importance: 5
}
var point_5 = new OpenLayers.Geometry.Point(263, 202);
var point_5_Feature = new OpenLayers.Feature.Vector(point_5);
point_5_Feature.attributes = {
strokeColor: "yellow",
fillColor: "yellow",
importance: 5
}
/* Layer Constructor */
/* In order to display the map, you must set a center and zoom level.
In order to zoom to fit the map into the window, you can use the
zoomToMaxExtent function, which will zoom as close as possible while still
fitting the full extents within the window. */
map.addLayers([basicMapLayer, monuments]);
map.zoomToMaxExtent();
// features for layer with cluster strategy must me declared after
layer is added in order to work
var monumentsFeature = new OpenLayers.Feature.Vector(
new
OpenLayers.Geometry.MultiPoint([point_1, point_2, point_3, point_4, point_5])
);
monuments.addFeatures([point_1_Feature, point_2_Feature,
point_3_Feature, point_4_Feature, point_5_Feature]);
// end of init function
}
</script>
</head>
<body onLoad="init()">
<div style="width:100%; height:100%; border:#000 1px solid;
background:#000000;" id="map"></div>
</body>
</html>
....................................................................
-----Original Message-----
From: Paul Spencer
Sent: Wednesday, February 16, 2011 3:37 PM
To: Mihai Visan
Cc: OpenLayers User list
Subject: Re: [OpenLayers-Users] cluster strategy
I don't know your code but I would assume that you are looking for something
like this:
var map = new OpenLayers.Map('mapDiv', mapOptions);
var clusterStrategy = new OpenLayers.Strategy.Cluster(clusterOptions);
var layerOptions = {
strategies: [clusterStrategy]
};
var vectorLayers = new OpenLayers.Layer.Vector('features', layerOptions);
// cluster threshold
var clusterMaxZoom = 10;
map.events.register('move', null, function() { // #2, #3 respond to map extent
change
// disable cluster when zoom greater than threshold
if (map.getZoom() > clusterMaxZoom) { // #2.1 how to read current zoom
clusterStrategy.deactivate(); // #2.2 how to disable cluster strategy
} else {
clusterStrategy.activate();
}
// filter features based on bounding box
var extent = map.getExtent(); // #3.1
// reload features here, it depends on how you read your features in now
});
If you are not using a Protocol like WFS () with your layer then the BBOX
strategy will have no effect and you will have to manually reload features
using whatever mechanism you are using now.
Cheers
Paul
On 2011-02-16, at 7:58 AM, Mihai Visan wrote:
> Thanks Paul,
>
> I already read the documentation and all tutorial and user discusions I could
> found.
>
> But I'm a week at javascript, so I could use some examples or tutorials I
> could transform
>
> -----Original Message----- From: Paul Spencer
> Sent: Wednesday, February 16, 2011 2:43 PM
> To: Mihai Visan
> Subject: Re: [OpenLayers-Users] cluster strategy
>
> Mihai, all of your questions have answers in the documentation ...
>
> On 2011-02-16, at 7:29 AM, Mihai Visan wrote:
>
>> 2. disable cluster strategy at certain zoom level.
>> Problems: 2.1. I don’t know how to read current zoom
>
> http://dev.openlayers.org/releases/OpenLayers-2.10/doc/apidocs/files/OpenLayers/Map-js.html#OpenLayers.Map.getZoom
>
>> 2.2. I don’t know to disable cluster strategy
>
> http://dev.openlayers.org/releases/OpenLayers-2.10/doc/apidocs/files/OpenLayers/Strategy/Cluster-js.html#OpenLayers.Strategy.Cluster.deactivate
>
>>
>> 3. use (BBOX strategy and) ajax to disable features outside visible bounds
>> Problems: 3.1. I don’t know how to read visible bounds
>
> http://dev.openlayers.org/releases/OpenLayers-2.10/doc/apidocs/files/OpenLayers/Map-js.html#OpenLayers.Map.getExtent
>
>> 3.2. I don’t know how to integrate ajax with (BBOX
>> and) mouse drag or zoom in/out
>
> http://dev.openlayers.org/releases/OpenLayers-2.10/doc/apidocs/files/OpenLayers/Map-js.html#OpenLayers.Map.EVENT_TYPES
>
> Cheers
>
> Paul
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