source: trunk/workshop-routing-foss4g/web/GeoExt/examples/zoom-chooser.js @ 76

/**
 * Copyright (c) 2008-2010 The Open Source Geospatial Foundation
 * 
 * Published under the BSD license.
 * See http://svn.geoext.org/core/trunk/geoext/license.txt for the full text
 * of the license.
 */

/** api: example[zoom-chooser]
 *  Scale Chooser
 *  -------------
 *  Use a ComboBox to display available map scales.
 */

var mapPanel;

Ext.onReady(function() {
    var map = new OpenLayers.Map();
    var layer = new OpenLayers.Layer.WMS(
        "Global Imagery",
        "http://maps.opengeo.org/geowebcache/service/wms",
        {layers: "bluemarble"}
    );
    map.addLayer(layer);

    var scaleStore = new GeoExt.data.ScaleStore({map: map});
    var zoomSelector = new Ext.form.ComboBox({
        store: scaleStore,
        emptyText: "Zoom Level",
        tpl: '<tpl for="."><div class="x-combo-list-item">1 : {[parseInt(values.scale)]}</div></tpl>',
        editable: false,
        triggerAction: 'all', // needed so that the combo box doesn't filter by its current content
        mode: 'local' // keep the combo box from forcing a lot of unneeded data refreshes
    });

    zoomSelector.on('select', 
        function(combo, record, index) {
            map.zoomTo(record.data.level);
        },
        this
    );     

    map.events.register('zoomend', this, function() {
        var scale = scaleStore.queryBy(function(record){
            return this.map.getZoom() == record.data.level;
        });

        if (scale.length > 0) {
            scale = scale.items[0];
            zoomSelector.setValue("1 : " + parseInt(scale.data.scale));
        } else {
            if (!zoomSelector.rendered) return;
            zoomSelector.clearValue();
        }
    });

    mapPanel = new GeoExt.MapPanel({
        title: "GeoExt MapPanel",
        renderTo: "mappanel",
        height: 400,
        width: 600,
        map: map,
        center: new OpenLayers.LonLat(5, 45),
        zoom: 4,
        bbar: [zoomSelector]
    });
});