+
+ blCorner: function(map, margin) {
+ var bounds = map.calculateBounds();
+ var corner = new OpenLayers.LonLat(bounds.left, bounds.bottom);
+ var cornerAsPx = map.getPixelFromLonLat(corner);
+ cornerAsPx = cornerAsPx.add( +margin, -margin);
+ return map.getLonLatFromPixel(cornerAsPx);
+ },
+
+ /* minimum bounds rectangle containing all feature locations.
+ * FIXME: if two features are close, but separated by 180th meridian,
+ * their mbr will span the whole earth. Actually, 179° lon and -170°
+ * lon are considerated very near.
+ */
+ mbr: function (layer) {
+ var features = [];
+ var map = layer.map;
+
+ var mapProj = map.getProjectionObject();
+ var sypOrigProj = new OpenLayers.Projection("EPSG:4326");
+
+ for (var i =0; i < layer.features.length; i++) {
+ if (layer.features[i].cluster) {
+ features = features.concat(layer.features[i].cluster);
+ } else {
+ features = features.concat(layer.features);
+ }
+ }
+
+ var minlon = 180;
+ var minlat = 88;
+ var maxlon = -180;
+ var maxlat = -88;
+
+ if (features.length == 0) {
+ // keep default values
+ } else if (features.length == 1) {
+ // in case there's only one feature, we show an area of at least
+ // 4 x 4 degrees
+ var pos = features[0].geometry.getBounds().getCenterLonLat().clone();
+ var lonlat = pos.transform(mapProj, sypOrigProj);
+
+ minlon = Math.max (lonlat.lon - 2, -180);
+ maxlon = Math.min (lonlat.lon + 2, 180);
+ minlat = Math.max (lonlat.lat - 2, -90);
+ maxlat = Math.min (lonlat.lat + 2, 90);
+ } else {
+ for (var i = 0; i < features.length; i++) {
+ var pos = features[i].geometry.getBounds().getCenterLonLat().clone();
+ var lonlat = pos.transform(mapProj, sypOrigProj);
+ minlon = Math.min (lonlat.lon, minlon);
+ minlat = Math.min (lonlat.lat, minlat);
+ maxlon = Math.max (lonlat.lon, maxlon);
+ maxlat = Math.max (lonlat.lat, maxlat);
+ }
+ }
+
+ return [minlon, minlat, maxlon, maxlat];
+
+ },
+