code: function(node, geometry, radius) {
          var resolution = this.getResolution();
          var x = ((geometry.x - this.featureDx) / resolution + this.left);
          var y = (this.top - geometry.y / resolution);
  
          if (this.inValidRange(x, y)) { 
              node.setAttributeNS(null, "cx", x);
              node.setAttributeNS(null, "cy", y);
              node.setAttributeNS(null, "r", radius);
              return node;
          } else {
              return false;
          }    
              
      }
docs: Method: drawCircle
  This method is only called by the renderer itself.
  
  Parameters:
  node - {DOMElement}
  geometry - {<OpenLayers.Geometry>}
  radius - {Float}
  
  Returns:
  {DOMElement} or false if the renderer could not draw the circle