First attempt for a current-view box

Customizations/AllKnownLayers.ts

@@ -20,7 +20,7 @@ export default class AllKnownLayers {
     public static sharedLayersJson: Map<string, any> = AllKnownLayers.getSharedLayersJson();
 
 
-    public static added_by_default: string[] = ["gps_location", "gps_location_history", "home_location", "gps_track",]
+    public static added_by_default: string[] = ["gps_location", "gps_location_history", "home_location", "gps_track","current_view"]
     public static no_include: string[] = ["conflation", "left_right_style", "split_point"]
     /**
      * Layer IDs of layers which have special properties through built-in hooks

Logic/State/MapState.ts

@@ -17,6 +17,7 @@ import {FeatureSourceForLayer, Tiled} from "../FeatureSource/FeatureSource";
 import SimpleFeatureSource from "../FeatureSource/Sources/SimpleFeatureSource";
 import {LocalStorageSource} from "../Web/LocalStorageSource";
 import {GeoOperations} from "../GeoOperations";
+import StaticFeatureSource from "../FeatureSource/Sources/StaticFeatureSource";
 
 /**
  * Contains all the leaflet-map related state
@@ -44,6 +45,7 @@ export default class MapState extends UserRelatedState {
         lon: number;
     }> = new UIEventSource<{ lat: number; lon: number }>(undefined);
 
+    public currentView: FeatureSourceForLayer
     /**
      * The location as delivered by the GPS
      */
@@ -125,6 +127,7 @@ export default class MapState extends UserRelatedState {
         this.initHomeLocation()
         this.initGpsLocation()
         this.initUserLocationTrail()
+        this.initCurrentView()
     }
 
     public AddAllOverlaysToMap(leafletMap: UIEventSource<any>) {
@@ -170,6 +173,34 @@ export default class MapState extends UserRelatedState {
         }
     }
     
+    private initCurrentView(){
+        const features : UIEventSource<{ feature: any, freshness: Date }[]>= this.currentBounds.map(bounds => {
+            const feature = {
+                freshness: new Date(),
+                feature: {
+                    type: "Polygon",
+                    properties:{
+                        id:"current_view"
+                    },
+                    geometry:{
+                        type:"Polygon",
+                        coordinates:[
+                            [bounds.maxLon, bounds.maxLat],
+                            [bounds.minLon, bounds.maxLat],
+                            [bounds.minLon, bounds.minLat],
+                            [bounds.maxLon, bounds.minLat],
+                            [bounds.maxLon, bounds.maxLat],
+                        ]
+                    }
+                }
+            }
+            return [feature]
+        })
+        let currentViewLayer: FilteredLayer = this.filteredLayers.data.filter(l => l.layerDef.id === "current_view")[0]
+
+        this.currentView = new SimpleFeatureSource(currentViewLayer,0,features)
+    }
+
     private initGpsLocation() {
         // Initialize the gps layer data. This is emtpy for now, the actual writing happens in the Geolocationhandler
         let gpsLayerDef: FilteredLayer = this.filteredLayers.data.filter(l => l.layerDef.id === "gps_location")[0]

assets/layers/current_view/current_view.json

@@ -1,3 +1,14 @@
 {
-
+  "id": "current_view",
+  "description": "A meta-layer which contains one single feature, namely the BBOX of the current map view. This can be used to trigger special actions. If a popup is defined for this layer, this popup will be accessible via an extra button on screen",
+  "source": {
+    "osmTags": "id=currentView"
+  },
+  "title": "Current View",
+  "tagRenderings": [],
+  "mapRendering": [
+    {
+      "color": "#cccc0088"
+    }
+  ]
 }