Feature: add possibility to show a scale on the map

src/Models/MapProperties.ts

@@ -22,6 +22,7 @@ export interface MapProperties {
     readonly lastClickLocation: Store<{ lon: number; lat: number }>
     readonly allowZooming: UIEventSource<true | boolean>
     readonly useTerrain: Store<boolean>
+    readonly showScale: UIEventSource<boolean>
 
     /**
      * Triggered when the user navigated by using the keyboard.

src/Models/ThemeViewState.ts

@@ -889,6 +889,9 @@ export default class ThemeViewState implements SpecialVisualizationState {
                 }
             })
         })
+        this.userRelatedState.showScale.addCallbackAndRun(showScale => {
+            this.mapProperties.showScale.set(showScale)
+        })
         new ThemeViewStateHashActor(this)
         new MetaTagging(this)
         new TitleHandler(this.selectedElement, this.featureProperties, this)