Question

I’m just getting started with OpenLayers, and have hit a small snag – when I create a LineString and then try to modify it, I can move the existing vertices and drag the virtual vertices to create new ones. When I continue to add to the line though, only the changes to the existing vertices are saved – new vertices are discarded. Am I missing something? You can see an example of what I’m talking about here:

http://dev.darrenhall.info/temp/open-layers/modify-feature/

Click to add points, and use the dots to edit, then click to continue adding to see what I mean. Any help would be appreciated! Thanks!

Darren

Answer 1

In the end I decided not to use modifyFeature, and instead went for using vectors as handles and manually handling the dragging and line modification. You can see my workaround here:

http://dev.darrenhall.info/temp/open-layers/draw-route

The guys at Ordnance Survey cam up with a (rather simple) fix for my code though that repopulates the array from the vertices after modification:

function addWayPoint(e) {    
  var position = osMap.getLonLatFromViewPortPx(e.xy);

  if(route.waypoints.length>1) {
        layers.lines.layer.removeFeatures([layers.lines.feature]);
  }

  /* vvvvvvvvvvv start */
  /* Get the potentially modified feature */

  if (modifyFeature.feature) {
      route.waypoints = [];
      var vertices = modifyFeature.feature.geometry.getVertices();

      for (i = 0; i < vertices.length; i++) {
          //console.log(vertices[i]);
          route.waypoints.push(vertices[i]);
      } 
  }

  /* ^^^^^^^^^^^ end */

  route.waypoints.push(new OpenLayers.Geometry.Point(position.lon, position.lat));

  var string = new OpenLayers.Geometry.LineString(route.waypoints);
  layers.lines.feature = new OpenLayers.Feature.Vector(string, null, styles.pink);
  layers.lines.feature.attributes['id']=1;
  layers.lines.layer.addFeatures([layers.lines.feature]);

  for (i = 0; i < layers.lines.layer.features.length; i++) {
        if (layers.lines.layer.features[i].attributes.id == 1) {
              modifyFeature.selectFeature(layers.lines.layer.features[i]);
        }
  }
}