feat: add mapId property for map styling

Close #58

Author: paodb

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

@@ -300,6 +300,25 @@ public void disableScaleControl(boolean disable) {
     this.getElement().setProperty("disableScaleControl", disable);
   }
 
+  /**
+   * Sets the mapId. See
+   * https://developers.google.com/maps/documentation/javascript/cloud-based-map-styling
+   * 
+   * @param mapId If set, the custom style associated with that map id is applied.
+   */
+  public void setMapId(String mapId) {
+    this.getElement().setProperty("mapId", mapId);
+  }
+
+  /**
+   * Returns the current map id.
+   *
+   * @return The current map id.
+   */
+  public String getMapId() {
+    return this.getElement().getProperty("mapId");
+  }
+  
   public static class GoogleMapClickEvent extends ClickEvent<GoogleMap> {
     private final double lat;
     private final double lon;
@@ -426,4 +445,5 @@ public Registration addGeolocationErrorEventListener(
       ComponentEventListener<GeolocationErrorEvent> listener) {
     return addListener(GeolocationErrorEvent.class, listener);
   }
+  
 }

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

@@ -0,0 +1,23 @@
+package com.flowingcode.vaadin.addons.googlemaps;
+
+import com.flowingcode.vaadin.addons.demo.DemoSource;
+import com.flowingcode.vaadin.addons.googlemaps.GoogleMap.MapType;
+import com.vaadin.flow.router.PageTitle;
+
+@PageTitle("MapId Styling Demo")
+@DemoSource(
+    "https://github.com/FlowingCode/GoogleMapsAddon/blob/master/src/test/java/com/flowingcode/vaadin/addons/googlemaps/CloudBasedMapStylingDemo.java")
+@SuppressWarnings("serial")
+public class CloudBasedMapStylingDemo extends AbstractGoogleMapsDemo {
+
+  @Override
+  protected void createGoogleMapsDemo(String apiKey) {
+    GoogleMap gmaps = new GoogleMap(apiKey, null, null);
+    gmaps.setMapType(MapType.ROADMAP);
+    gmaps.setSizeFull();
+    gmaps.setCenter(new LatLon(-31.636036, -60.7055271));
+    gmaps.setMapId("8e0a97af9386fef");
+    add(gmaps);
+  }
+
+}

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

@@ -36,6 +36,7 @@ public GooglemapsDemoView() {
     addDemo(new GeolocationDemo());
     addDemo(new DraggableMarkerDemo());
     addDemo(new DisableUIControlsDemo());
+    addDemo(new CloudBasedMapStylingDemo());
     setSizeFull();
   }
 }