[GIS] Dynamically adding features with cluster strategy

clusteringdynamicfeaturesopenlayers-2vector

I am trying to dynamically add features to a vector layer, and use cluster strategy to group those features accordingly.

I am able to do this for the first set of data that gets loaded on the map.

It looks like below code works only the first time –
vectorLayer.addFeatures(vectordArray);

when i try to call the same addFeatures again with a new set of vectors, I dont see the new vectors. There are no errors either.

Anyone faced a situation like this? I am looking to dynamically add vectors and use CluseterStrategy.

Best Answer

did you try to update your vector layer after this vectorLayer.addFeatures(vectordArray) as shown at following code:

vectorLayer.redraw();

if this not work try to get all features from map into an array and then merge them with your new array then add them to map as if you are adding first time into map...

vectorLayer.removeFeatures(vectorLayer.features);
vectorLayer.addFeatures(newFeatures);

beside this checking out this example here may be helpful for you... it is working on the same principle as your will.

i hope it helps you...

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[GIS] Problems with features, popups and strategy with OpenLayers

you can catch your opened(active) popup with this way:

map.popups[a]

you can change so update its content:

map.popups[a].contentHTML = 'Test Content';
map.popups[a].redraw();

or

map.popups[a].setContentHTML = 'Test Content'

you can show or hide your popup:

map.popups[a].show();
map.popups[a].hide();

you can update position of your popup:

map.popups[a].lonlat.lon = 10;
map.popups[a].lonlat.lat = 10;
map.popups[a].updatePosition();

for openlayers cluster you should check out Cluster Strategy Example here. Only one thing you should do is that define fillColor or externalGraphic for your cluster.

          var style = new OpenLayers.Style({
                pointRadius: "${radius}",
                fillColor: "${getColor}",
                fillOpacity: 0.8,
                strokeColor: "#cc6633",
                strokeWidth: 2,
                strokeOpacity: 0.8
            }, {
                context: {
                    radius: function(feature) {
                        return Math.min(feature.attributes.count, 7) + 3;
                    },
                    getColor: function(feature) {
                        return // Your color selection logic;
                    }
                }
            });

As the last question, i dont understand very well what you want? but try to use removeFeatures instead of destroyFeatures....

i hope it helps you...

[GIS] Slow IE8 responsiveness with OpenLayers and many features

Use a Cluster Strategy in combination with a BBOX Strategy.

Perhaps you should come at this from a different angle. You are not far off with your Restrict Area idea. Don't dismiss this idea too soon as reducing the usefulness of the tool.

In your current approach you are loading all sites at once and then adding them to a vector layer. This means that at any one time there is the potential that the browser will contain more data than the user can see (depending on zoom level etc) as most data will be outside of their viewport bounds. You can utilise this fact to optimise the loading of the data into the user's browser by only requesting the data from the server that falls within the bounds of the user's current view.

You can implement a BBOX refresh strategy to your vector layer by adding a OpenLayers.Strategy.BBOX strategy object to your vector layer. When the view is invalidated (by a pan or zoom action) the BBOX strategy will cause the layer to request new data from the backend server. To implement this approach you will need to tweak your server side function to accept the additional parameters OpenLayers will add to the data request and you will also need to return the data in a format that can be read by OpenLayers. It is pretty straight forward to implement and you should notice a massive increase in performance across all browsers.

There is an example on the OpenLayers website of implementing the BBOX strategy. You could also consider adding a Cluster strategy for small scales when there is potentially large volumes of features returned from a request, or implement some scale dependent rendering of the layer.

Best Answer

Related Solutions

[GIS] Problems with features, popups and strategy with OpenLayers

[GIS] Slow IE8 responsiveness with OpenLayers and many features

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