UX: update 'distance' indicator faster while dragging the map

src/UI/InputElement/Helpers/LocationInput.svelte

@@ -50,6 +50,7 @@
   mla.lastClickLocation.addCallbackAndRunD((lastClick) => {
     dispatch("click", lastClick)
   })
+  mla.installQuicklocation()
   mapProperties.location.syncWith(value)
   if (onCreated) {
     onCreated(value, map, mla)

src/UI/Map/MapLibreAdaptor.ts

@@ -757,4 +757,28 @@ export class MapLibreAdaptor implements MapProperties, ExportableMap {
             })
         })
     }
+
+    /**
+     * In general, the 'location'-attribute is only updated when the map stops moving.
+     * In some cases, we'd like to update the map faster, especially when the map is used for an input-element
+     * such as distance, snap-to, ...
+     *
+     * In that case, calling this method will install an extra handler on 'drag', updating the location faster.
+     * To avoid rendering artefacts or too frequenting pinging, this is ratelimited to one update every 'rateLimitMs' milliseconds
+     */
+    public installQuicklocation(ratelimitMs = 50) {
+        this._maplibreMap.addCallbackAndRunD(map => {
+            let lastUpdate = new Date().getTime()
+            map.on("drag", e => {
+                let now = new Date().getTime()
+                if(now - lastUpdate < ratelimitMs){
+                    return
+                }
+                lastUpdate = now;
+                const center = map.getCenter()
+                this.location.set({lon: center.lng, lat: center.lat})
+            })
+        })
+
+    }
 }