[OpenLayers-Users] Browser slow performance while parsing OpenLayers.Vector.Feature features : SLDSELECT??

[Phil Scadden]

So do you HAVE to use WFS? I had a similar problem,

Have a look at http://dev.openlayers.org/releases/OpenLayers-2.10/examples/

The idea is to have the server draw the selected polygons via WMS and 
have  WFS query return the attribute data.
My code was something like this:

                polySelectControl[i] = new 
OpenLayers.Control.SLDSelect(OpenLayers.Handler.Polygon,
                          {
                              displayClass: 'olControlSLDSelectPolygon',
                              layers:[layer[i]]
                          });
                  polySelectControl[i].events.register("selected", this, 
function(e){
// next bit of code selects ONLY the fields to return which are read 
from a JSON config file. This step reduces the amount of web traffic but 
more importantly, ensures that geometry is not sent.
                          clearData();
                          var propNames = [];
                          var layerNode = getLayerNode(combo.value);
                          var SpatialQueryNode =layerNode.spatialQuery[0];
                          for (var i = 0; i < 
SpatialQueryNode.fields.length; i++) {
                              propNames[i] = SpatialQueryNode.fields[i].id;
                          }
// Now set up the wfs to return the attribute data associated with propNames
                          wfsProtocol[combo.value].read({
                             filter: e.filters[0],
                             propertyNames: propNames,
                             callback: processSpatialQuery,
                             scope: strategy
                          });
                  });*/
                  mapPanel.map.addControl(polySelectControl[i]);

All very nice but you need to be aware that geoserver has an unresolved 
problem with SLD filters. If the WFS layers has different projection to 
your map projection, then this doesnt work. I understand mapserver 
doesnt have this problem.
I've worked out an ugly workaround (reproject the polygon before sending 
the SLD filter) but havent had time to hack the openlayers code to 
implement it. I dont know what the status of in geoserver is but I am 
guessing you will get no sense from geoserver developers on new issues 
till 2.1 is finally out. In short term, I made life a lot easily by 
generalising the line work but that might be tricky with cadastre.
-- 
Phil Scadden, Senior Scientist GNS Science Ltd 764 Cumberland St, 
Private Bag 1930, Dunedin, New Zealand Ph +64 3 4799663, fax +64 3 477 5232

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