Example demonstrating scale dependent labeling.

git-svn-id: http://svn.openlayers.org/trunk/openlayers@12167 dc9f47b5-9b13-0410-9fdd-eb0c1a62fdaf

examples/label-scale.js

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+// Create 50 random features, and give them a "type" attribute that
+// will be used for the label text.
+var features = new Array(50);
+for (var i=0; i<features.length; i++) {
+    features[i] = new OpenLayers.Feature.Vector(
+        new OpenLayers.Geometry.Point(
+            (360 * Math.random()) - 180, (180 * Math.random()) - 90
+        ), {
+            type: 5 + parseInt(5 * Math.random())
+        }
+    );
+}
+
+/**
+ * Create a style instance that is a collection of rules with symbolizers.
+ * Use a default symbolizer to extend symoblizers for all rules.
+ */
+var style = new OpenLayers.Style({
+    fillColor: "#ffcc66",
+    strokeColor: "#ff9933",
+    strokeWidth: 2,
+    label: "${type}",
+    fontColor: "#333333",
+    fontFamily: "sans-serif",
+    fontWeight: "bold"
+}, {
+    rules: [
+        new OpenLayers.Rule({
+            minScaleDenominator: 200000000,
+            symbolizer: {
+                pointRadius: 7,
+                fontSize: "9px"
+            }
+        }),
+        new OpenLayers.Rule({
+            maxScaleDenominator: 200000000,
+            minScaleDenominator: 100000000,
+            symbolizer: {
+                pointRadius: 10,
+                fontSize: "12px"
+            }
+        }),
+        new OpenLayers.Rule({
+            maxScaleDenominator: 100000000,
+            symbolizer: {
+                pointRadius: 13,
+                fontSize: "15px"
+            }
+        })
+    ]
+});
+
+// Create a vector layer and give it your style map.
+var points = new OpenLayers.Layer.Vector("Points", {
+    styleMap: new OpenLayers.StyleMap(style)
+});
+points.addFeatures(features);
+
+var map = new OpenLayers.Map({
+    div: "map",
+    layers: [
+        new OpenLayers.Layer.WMS(
+            "OpenLayers WMS",
+            "http://vmap0.tiles.osgeo.org/wms/vmap0",
+            {layers: "basic"}
+        ),
+        points
+    ],
+    center: new OpenLayers.LonLat(0, 0),
+    zoom: 1
+});
+