refactor!: internally manage trackLocationId

Close #133

Author: paodb

src/main/java/com/flowingcode/vaadin/addons/googlemaps/GoogleMap.java

@@ -51,6 +51,8 @@
 @JsModule("./googlemaps/geolocation.js")
 public class GoogleMap extends Component implements HasSize {
 
+  private Integer trackLocationId = null;
+
   /** Base map types supported by Google Maps. */
   public enum MapType {
     ROADMAP,
@@ -619,28 +621,37 @@ public Registration addGeolocationErrorEventListener(
    * 
    * <p>Geolocation requires that the user gives consent to location sharing when prompted by the
    * browser.</p>
+   * 
+   * @throws IllegalStateException if a tracking location session is already active. 
+   *         The current session must be stopped before starting a new one.
    */
   public void trackLocation() {
-    getElement().executeJs("return geolocation.trackLocation($0)", this).then(Integer.class,
-        trackLocationId -> {
-          ComponentUtil.fireEvent(this,
-              new LocationTrackingActivatedEvent(this, false, trackLocationId));
-        });
+    if (this.getTrackLocationId() == null) {
+      getElement().executeJs("return geolocation.trackLocation($0)", this).then(Integer.class,
+          trackLocationId -> {
+            this.trackLocationId = trackLocationId;
+            ComponentUtil.fireEvent(this, new LocationTrackingActivatedEvent(this, false));
+          });
+    } else {
+      throw new IllegalStateException(
+          "A tracking location session is already active. Please stop the current session before starting a new one.");
+    }
+  }
+  
+  /**
+   * Returns track location id if a location tracking was activated.
+   * 
+   * @return the location tracking id
+   */
+  public Integer getTrackLocationId() {
+    return trackLocationId;
   }
 
   /** Event that is fired when activating location tracking. */
   public class LocationTrackingActivatedEvent extends ComponentEvent<GoogleMap> {
 
-    private Integer trackLocationId;
-
-    public LocationTrackingActivatedEvent(GoogleMap source, boolean fromClient,
-        Integer trackLocationId) {
+    public LocationTrackingActivatedEvent(GoogleMap source, boolean fromClient) {
       super(source, fromClient);
-      this.trackLocationId = trackLocationId;
-    }
-
-    public Integer getTrackLocationId() {
-      return trackLocationId;
     }
   }
 
@@ -657,14 +668,15 @@ public Registration addLocationTrackingActivatedEventListener(
   }
 
   /**
-   * Stops location tracking.
-   * 
-   * @param trackLocationId the id of the current activated location tracking
+   * Stops the current location tracking session.
    */
-  public void stopTrackLocation(Integer trackLocationId) {
-    getElement().executeJs("geolocation.clearTracking($0)", trackLocationId);
+  public void stopTrackLocation() {
+    if(trackLocationId != null) {
+      getElement().executeJs("geolocation.clearTracking($0)", trackLocationId);
+      trackLocationId = null;
+    }    
   }
-  
+
   /**
    * Returns a {@link CompletableFuture} containing the map current {@link LatLonBounds bounds}.
    * 

src/test/java/com/flowingcode/vaadin/addons/googlemaps/TrackLocationDemo.java

@@ -24,6 +24,7 @@
 import com.flowingcode.vaadin.addons.googlemaps.GoogleMap.MapType;
 import com.vaadin.flow.component.button.Button;
 import com.vaadin.flow.component.notification.Notification;
+import com.vaadin.flow.component.orderedlayout.HorizontalLayout;
 import com.vaadin.flow.router.PageTitle;
 import com.vaadin.flow.router.Route;
 
@@ -33,8 +34,6 @@
 @SuppressWarnings("serial")
 public class TrackLocationDemo extends AbstractGoogleMapsDemo {
 
-  private Integer trackLocationId = null;
-
   @Override
   protected void createGoogleMapsDemo(String apiKey) {
     GoogleMap gmaps = new GoogleMap(apiKey, null, null);
@@ -43,23 +42,32 @@ protected void createGoogleMapsDemo(String apiKey) {
     gmaps.setZoom(15);
     add(gmaps);
 
-    // create button to activate location tracking
-    Button startLocationTrackingButton =
-        new Button("Start tracking my location", e -> gmaps.trackLocation());
-    // create button to stop location tracking
-    Button stopLocationTrackingButton =
-        new Button("Stop tracking my location", e -> gmaps.stopTrackLocation(trackLocationId));
-    add(startLocationTrackingButton, stopLocationTrackingButton);
+    // create buttons to activate/stop location tracking
+    Button startLocationTrackingButton = new Button("Start tracking my location");
+    Button stopLocationTrackingButton = new Button("Stop tracking my location");
+    startLocationTrackingButton.addClickListener(e -> {
+      gmaps.trackLocation();
+      stopLocationTrackingButton.setEnabled(true);
+    });
+    startLocationTrackingButton.setDisableOnClick(true);
+    stopLocationTrackingButton.addClickListener(e -> {
+      gmaps.stopTrackLocation();
+      startLocationTrackingButton.setEnabled(true);
+    });
+    stopLocationTrackingButton.setEnabled(false);
+    stopLocationTrackingButton.setDisableOnClick(true);
+    add(new HorizontalLayout(startLocationTrackingButton, stopLocationTrackingButton));
 
     // create marker to track location
     GoogleMapMarker locationMarker = new GoogleMapMarker();
     locationMarker.setCaption("You're here");
     locationMarker.setDraggable(false);
     gmaps.addMarker(locationMarker);
 
-    // add listener to obtain id when track location is activated
+    // add listener to show notification as track location is activated
     gmaps.addLocationTrackingActivatedEventListener(ev -> {
-      trackLocationId = ev.getTrackLocationId();
+      Notification
+          .show("Location tracking was activated with track id: " + gmaps.getTrackLocationId());
     });
 
     // add listener to know when location was updated and update location marker position
@@ -68,9 +76,8 @@ protected void createGoogleMapsDemo(String apiKey) {
     });
 
     // add listener to capture geolocation error
-    gmaps.addGeolocationErrorEventListener(e -> {
-      if (!e.isBrowserHasGeolocationSupport())
-        Notification.show("Your browser doesn't support geolocation.");
-    });
+    gmaps.addGeolocationErrorEventListener(e -> Notification.show(e.isBrowserHasGeolocationSupport()
+        ? "The geolocation service failed on retrieving your location."
+        : "Your browser doesn't support geolocation."));
   }
 }