openstreetmap-website/public/javascripts/map.js

var map;
var markers;
var popup;

OpenLayers._getScriptLocation = function () {
   return "/openlayers/";
}
   
function createMap(divName) {
   map = new OpenLayers.Map(divName);

   var mapnik = new OpenLayers.Layer.OSM.Mapnik("Mapnik", { displayOutsideMaxExtent: true });
   map.addLayer(mapnik);

   var osmarender = new OpenLayers.Layer.OSM.Osmarender("Osmarender", { displayOutsideMaxExtent: true });
   map.addLayer(osmarender);

   var maplint = new OpenLayers.Layer.OSM.Maplint("Maplint", { displayOutsideMaxExtent: true });
   map.addLayer(maplint);

   var numZoomLevels = Math.max(mapnik.numZoomLevels, osmarender.numZoomLevels);
   markers = new OpenLayers.Layer.Markers("Markers", { 
      displayInLayerSwitcher: false, numZoomLevels: numZoomLevels,
      maxExtent: new OpenLayers.Bounds(-20037508,-20037508,20037508,20037508),
      maxResolution: 156543,
      units: "m",
      projection: "EPSG:41001"
   });
   map.addLayer(markers);

   map.addControl(new OpenLayers.Control.LayerSwitcher());
   map.addControl(new OpenLayers.Control.KeyboardDefaults());

   return map;
}

function getArrowIcon() {
   var size = new OpenLayers.Size(25, 22);
   var offset = new OpenLayers.Pixel(-30, -27);
   var icon = new OpenLayers.Icon("/images/arrow.png", size, offset);

   return icon;
}

function addMarkerToMap(position, icon, description) {
   var marker = new OpenLayers.Marker(position, icon);

   markers.addMarker(marker);

   if (description) {
      marker.events.register("click", marker, function() { openMapPopup(marker, description) });
   }

   return marker;
}

function openMapPopup(marker, description) {
   closeMapPopup();

   popup = new OpenLayers.Popup.AnchoredBubble("popup", marker.lonlat,
                                               sizeMapPopup(description),
                                               "<p style='padding-right: 28px'>" + description + "</p>",
                                               marker.icon, true);
   popup.setBackgroundColor("#E3FFC5");
   map.addPopup(popup);

   return popup;
}

function closeMapPopup() {
   if (popup) {
      map.removePopup(popup);
      delete popup;
   }
}

function sizeMapPopup(text) {
   var box = document.createElement("div");

   box.innerHTML = text;
   box.style.visibility = "hidden";
   box.style.position = "absolute";
   box.style.top = "0px";
   box.style.left = "0px";
   box.style.width = "200px";
   box.style.height = "auto";

   document.body.appendChild(box);

   var width = box.offsetWidth;
   var height = box.offsetHeight;

   document.body.removeChild(box);

   return new OpenLayers.Size(width + 30, height + 24);
}

function removeMarkerFromMap(marker){
   markers.removeMarker(marker);
}

function getMapLayers() {
   var layers = "";

   for (var i=0; i< this.map.layers.length; i++) {
      var layer = this.map.layers[i];

      if (layer.isBaseLayer) {
         layers += (layer == this.map.baseLayer) ? "B" : "0";
      } else {
         layers += (layer.getVisibility()) ? "T" : "F";
      }
   }

   return layers;
}

function setMapLayers(layers) {
   for (var i=0; i < layers.length; i++) {
      var layer = map.layers[i];
      var c = layers.charAt(i);

      if (c == "B") {
         map.setBaseLayer(layer);
      } else if ( (c == "T") || (c == "F") ) {
         layer.setVisibility(c == "T");
      }
   }
}

function mercatorToLonLat(merc) {
   var lon = (merc.lon / 20037508.34) * 180;
   var lat = (merc.lat / 20037508.34) * 180;

   lat = 180/Math.PI * (2 * Math.atan(Math.exp(lat * Math.PI / 180)) - Math.PI / 2);

   return new OpenLayers.LonLat(lon, lat);
}

function lonLatToMercator(ll) {
   var lon = ll.lon * 20037508.34 / 180;
   var lat = Math.log(Math.tan((90 + ll.lat) * Math.PI / 360)) / (Math.PI / 180);

   lat = lat * 20037508.34 / 180;

   return new OpenLayers.LonLat(lon, lat);
}

// for interacting with the PostGIS database which uses non spherical
// Mercator. Taken from Freemap which in turn was taken from a standard
// algorithm off the net.

function lonLatToNonSphericalMercator(ll) {
    var custLat  = ll.lat * (Math.PI/180);
    var a = 6378137;
    var b = 6356752.3142;
    var f = (a-b)/a;
    var e = Math.sqrt(2*f-Math.pow(f,2));
    custLat=a*Math.log(Math.tan(Math.PI/4+custLat/2)*
        Math.pow(( (1-e*Math.sin(custLat)) / (1+e*Math.sin(custLat))),e/2));
    custLon = ll.lon * (Math.PI/180) * 6378137;
    return new OpenLayers.LonLat (custLon,custLat);
}

function nonSphericalMercatorToLonLat(merc) {
    var lon_deg, lat_deg;
    var a = 6378137.0;
    var b = 6356752.3142;
    var k0 = 1.0;
    var t = 1.0 - b/a;
    var es = 2*t - t*t;
    var e = Math.sqrt(es);
    lon_deg = merc.lon;
    lat_deg = merc.lat;
    lon_deg /= a;
    lat_deg /= a;
    lon_deg /= k0;
    lat_deg = phi2(Math.exp(-lat_deg/k0), e);
    lon_deg *= (180/M_PI);
    lat_deg *= (180/M_PI);
    return new OpenLayers.LonLat(lon_deg,lat_deg);
}

function phi2 (ts,e) {
    var eccnth = 0.5*e;
    var Phi = (PI/2) - 2.0*Math.atan(ts);
    var dphi;
    var i=15;
    do {
        var con = e*Math.sin(Phi);
        dphi = (PI/2) - 2.0*Math.atan(ts*Math.pow((1.0-con)/(1.0+con),eccnth))
            - Phi;
        Phi += dphi;
    }
    while(Math.abs(dphi) > 0.0000000001 && --i);
    return Phi;
}

function scaleToZoom(scale) {
   return Math.log(360.0/(scale * 512.0)) / Math.log(2.0);
}