[GIS] How to change the appearance of a Feature.Vector that’s already displayed

openlayers-2symbology

I've created a bunch of Feature.Vectors from Point objects and assigned them a Style. Now I want to dynamically change the appearance of one of the features in real time; e.g., change it from red to blue. (I am NOT hovering over the feature.) I've tried changing its Style, then doing refresh() on the layer, or redraw(), etc, and either nothing happens or the feature disappears. Any suggestions? Thanks.

Best Answer

Redraw method should solve your problem, see my little example: OpenLayers: modifying feature style

UPD: I've modified my example a little bit: OpenLayers: modifying one feature style

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[GIS] OpenLayers GeoJSON Data Store

One thing that you could do is long polling. Leave your HTTP connection open until something has changed, and then close it. This is easy with OpenLayers, using e.g. (untested):

layer.events.register("loadend", this, function() {
    layer.refresh({params: {poll: true}});
});

On the server, you would look at the request string, and if it has a poll param set to true, you would not close the request until something has changed.

[GIS] How to modify a Marker object’s icon after it’s been drawn

I have not tried the following code, but I am reasonably sure you should be able to change a marker's icon by simply:

marker.setUrl('http://url.of.your.icon/icon.png');

hide it:

marker.display(false);

enlarge the icon (might pixelize with certain formats):

// 2 = double the size
marker.inflate(2);

Look at source (https://github.com/openlayers/openlayers/blob/master/lib/OpenLayers/Marker.js) for more information.

Best Answer

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