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var map;
function init() {
map = new OpenLayers.Map("map");
var wms = new OpenLayers.Layer.WMS(
"OpenLayers WMS",
"http://vmap0.tiles.osgeo.org/wms/vmap0",
{layers: "basic"}
);
/**
* Create 50 vector features. Your features would typically be fetched
* from the server. These are created here to demonstrate a rule based
* style. The features are given an attribute named "foo". The value
* of this attribute is an integer that ranges from 0 to 100.
*/
var features = new Array(25);
for (var i=0; i<features.length; i++) {
features[i] = new OpenLayers.Feature.Vector(
new OpenLayers.Geometry.Point(
(340 * Math.random()) - 170,
(160 * Math.random()) - 80
), {
foo: 100 * Math.random() | 0
}
);
}
/**
* Here we create a new style object with rules that determine
* which symbolizer will be used to render each feature.
*/
var style = new OpenLayers.Style(
// the first argument is a base symbolizer
// all other symbolizers in rules will extend this one
{
graphicWidth: 21,
graphicHeight: 25,
graphicYOffset: -28, // shift graphic up 28 pixels
label: "${foo}" // label will be foo attribute value
},
// the second argument will include all rules
{
rules: [
new OpenLayers.Rule({
// a rule contains an optional filter
filter: new OpenLayers.Filter.Comparison({
type: OpenLayers.Filter.Comparison.LESS_THAN,
property: "foo", // the "foo" feature attribute
value: 25
}),
// if a feature matches the above filter, use this symbolizer
symbolizer: {
externalGraphic: "openlayers/img/marker-blue.png"
}
}),
new OpenLayers.Rule({
filter: new OpenLayers.Filter.Comparison({
type: OpenLayers.Filter.Comparison.BETWEEN,
property: "foo",
lowerBoundary: 25,
upperBoundary: 50
}),
symbolizer: {
externalGraphic: "openlayers/img/marker-green.png"
}
}),
new OpenLayers.Rule({
filter: new OpenLayers.Filter.Comparison({
type: OpenLayers.Filter.Comparison.BETWEEN,
property: "foo",
lowerBoundary: 50,
upperBoundary: 75
}),
symbolizer: {
externalGraphic: "openlayers/img/marker-gold.png"
}
}),
new OpenLayers.Rule({
// apply this rule if no others apply
elseFilter: true,
symbolizer: {
externalGraphic: "openlayers/img/marker.png"
}
})
]
}
);
// create the layer styleMap that uses the above style for all render intents
var vector = new OpenLayers.Layer.Vector("Points", {
styleMap: new OpenLayers.StyleMap(style)
});
vector.addFeatures(features);
map.addLayers([wms, vector]);
map.setCenter(new OpenLayers.LonLat(0, 0), 1);
}
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