added fixed center option

added option to fix the map on a specific coordinate

README.md

@@ -84,6 +84,22 @@ property and optionally `url` and `config` properties. If no `url` is supplied
 `name` is assumed to name a
 [Leaflet-provider](http://leaflet-extras.github.io/leaflet-providers/preview/).
 
+## fixedCenter (array, optional)
+
+This option allows to fix the map at one specific coordinate depending on following case-sensitive parameters:
+
+- `lat` latitude of the center point
+- `lng` longitude of the center point
+- `radius` visible radius around the center in km
+
+Examples for `fixedCenter`:
+
+    "fixedCenter": {
+      "lat": 50.80,
+      "lng": 12.07,
+      "radius": 30
+    }
+
 ## nodeInfos (array, optional)
 
 This option allows to show node statistics depending on following case-sensitive parameters:

lib/map.js

@@ -447,7 +447,10 @@ define(["map/clientlayer", "map/labelslayer",
         var lines = addLinksToMap(linkDict, linkScale, data.graph.links, router)
         groupLines = L.featureGroup(lines).addTo(map)
 
+        if (typeof config.fixedCenter === "undefined")
           barycenter = calcBarycenter(data.nodes.all.filter(has_location))
+        else
+          barycenter = L.circle(L.latLng(new L.LatLng(config.fixedCenter.lat, config.fixedCenter.lng)), config.fixedCenter.radius * 1000)
 
         var nodesOnline = subtract(data.nodes.all.filter(online), data.nodes.new)
         var nodesOffline = subtract(data.nodes.all.filter(offline), data.nodes.lost)