[OpenLayers-Users] Style, Rule and Comparison

[Gwennaël matot]

Hi list !

I'd like some clarification on the use of the "Comparison" class.
I have many feature defined with GeoJSON. I want to change style of 
feature according to an attribute "nb_voyage".
Here a part of my test :

   /* DATA */
   var waypoints = {
       type: "FeatureCollection",
       features: [{
           type: "Feature",
           geometry: { type: "LineString", coordinates: [ [ 
0.04863281249999929, 40.00107421875 ] , [ 0.3452636718749993, 
38.81455078125 ] ] },
           crs: { type: "OGC", properties: { urn: 
"urn:ogc:def:crs:OGC:1.3:CRS84" } },
           properties: { nb_voyage: 3, from: "Point 1", to: "Point 10" }
       },{
           type: "Feature",
           geometry: { type: "LineString", coordinates: [ [ 
-0.3139160156250007, 39.495703125 ] , [ 0.3452636718749993, 
38.81455078125 ] ] },
           crs: { type: "OGC", properties: { urn: 
"urn:ogc:def:crs:OGC:1.3:CRS84" } },
           properties: { nb_voyage: 18, from: "Point 5", to: "Point 8" }
       }]
   };

   /* BUILD STYLE */
   var style = new OpenLayers.Style({strokeOpacity: 1, strokeLinecap: 
"round", strokeWidth: 2});
   var ruleLow = new OpenLayers.Filter.Comparison({
       type: OpenLayers.Filter.Comparison.LESS_THAN,
       property: "nb_voyage",
       value: 15,
       symbolizer: {strokeColor: "#FF0000" }
   });
   var ruleHigh = new OpenLayers.Filter.Comparison({
       type: OpenLayers.Filter.Comparison.GREATER_THAN_OR_EQUAL_TO,
       property: "nb_voyage",
       value: 15,
       symbolizer: {strokeColor: "#00FF00" }
   });
   var elseRule = new OpenLayers.Rule({
       elseFilter: true,
       symbolizer: {strokeColor: "#0000FF" }
   });
   style.addRules([ruleLow, ruleHigh, elseRule]);
     /* ADD DATA TO LAYER */
   var geojson_format = new OpenLayers.Format.GeoJSON();
   var layer = new OpenLayers.Layer.Vector("mylayer", {
       styleMap: new OpenLayers.StyleMap({
           default: style
       })
   });
   layer.addFeatures(geojson_format.read(waypoints));
   map.addLayer(layer);

But the elseFilter rule is always applied !

After many trackback I saw in Comparison.evaluate(context) function that 
"context" is the feature.
The comparison is done on the root properties of the feature 
(feature.nb_voyage), but my attribute is in "attributes" 
(feature.attributes.nb_voyage).
Can i change this way ?

Thanks for your help
Gwennaël Matot


PS : the features are like to :
feature: {
   CLASS_NAME: "OpenLayers.Feature.Vector",
   attributes: {
       from: "Point 1"
       to: "Point 2"
       nb_voyage: 5
   },
   data: {
       from: "Point 1"
       to: "Point 2"
       nb_voyage: 5
   },
   geometry: ...,
   renderIntent: "default",
   style: null,
   ...
}

-------------- next part --------------
An HTML attachment was scrubbed...
URL: http://lists.osgeo.org/pipermail/openlayers-users/attachments/20080620/e520c87b/attachment.html