Question

I am quite new to OpenLayers. Right now, I have a polygon vector with some styling applied and a label.

var style = $.extend(true, {}, OpenLayers.Feature.Vector.style['default']);
style.pointRadius = 15;
style.label = "My Polygon";
style.fillColor = #f00;
style.strokeColor = #000;

var styleMap = new OpenLayers.StyleMap({"default" : style});

var polygonLayer = new OpenLayers.Layer.Vector("Polygon Layer", {styleMap: styleMap});

At some point after doing some processing, I want to display the result as a label. How can I update the label? I figure it would be something like this, but this wasn’t the way.

polygonLayer.options.styleMap.styles.label = "Updated label";

Thanks in advance.

Answer 1

You are on the right way. You can set new label for all features in a layer like that:

polygonLayer.styleMap.styles.default.defaultStyle.label = "new label";
polygonLayer.redraw();

As you see it’s important to call redraw() method after you set new value.

That’s how you change label for all features in a layer. Quite often though you’ll need to set new labels per feature. To achieve that you should do following when you create pollygonLayer:

var style = $.extend(true, {}, OpenLayers.Feature.Vector.style['default']);
style.label = "${feature_name}";

Each feature has a collection of attributes. In this case value of attribute feature_name will be displayed as a label. To change label value per feature you simply change value of the attribute on that feature and then of course call redraw() on layer.