Question

Is it possible to add points to an existing linestring in openlayers? I have a stream of points coming from the server that I wish to draw when they arrive on the client. Currently, the only way I can see to do this is to draw a single line from the last point that I received to the new point each time a new point comes in, like so:

Drawer.prototype.drawPoint = function(point)
{
    var line = new OpenLayers.Geometry.LineString([this.lastPoint, point]);
    var lineFeature = new OpenLayers.Feature.Vector(line, null, this.style);
    this.lineLayer.addFeatures([lineFeature]);
    this.lastPoint = point;
}

This seems inefficient. Obviously I could keep an array of all of the points and redraw the whole line each time a new point comes in, but that seems inefficient too.

Answer 1

OpenLayers.Geometry.LineString has a method addPoint(point, index) through the OpenLayers.Geometry.MultiPoint class that it derives from, take a look at the source code.

So your solution should be as simple as:

line.addPoint(point); //second parameter(index) is optional

You will probably need to call redraw() method on the layer as well.