Navigation Events

NavigationManager Listeners

NavigationManager contains a number of listeners that are responsible for monitoring navigation status and getting instructions during navigation. The following table shows the name of the available listeners and the information provided to them.

Listener instances can be added to Navigation Manger through their respective add and remove methods. For example, LaneInformationListener can be added and removed by using addLaneInformationListener(WeakReference<LaneInformationListener>) and removeLaneInformationListener(WeakReference<LaneInformationListener>).

New Instructions and Maneuvers

@Override
public void onNewInstructionEvent() {
  Maneuver maneuver = navigationManager.getNextManeuver();
  if (maneuver != null) {
    if (maneuver.getAction() == Maneuver.Action.END) {
      // notify the user that the route is complete
    }

    // display current or next road information
    // display maneuver.getDistanceToNextManeuver()
  }
}

Rerouting

@Override
public void onRouteUpdated(@NonNull Route updatedRoute) {
  // remove old MapRoute object from the map
  m_map.removeMapObject(m_currentMapRoute);
  // create a new MapRoute object
  m_currentMapRoute = new MapRoute(updatedRoute);
  // display new route on the map
  m_map.addMapObject(m_currentMapRoute);
}

You can find example that demonstrates the rerouting feature in Advanced Navigation project at https://github.com/heremaps/.

Lane Information

NavigationManager.LaneInformationListener provides onLaneInformation(List<LaneInformation>, RoadElement) callback method. This callback occurs when the user has arrived at a point in the route where lane information should be presented, e.g. before a highway exit. LaneInformation class represents a lane turn direction and whether this lane is on the current route. For example, an application may receive onLaneInformation(List<LaneInformation>, RoadElement) callback as the user navigates to an intersection. If the route requires a left turn and the current road has three lanes — a left-turn lane and two straight lanes — then the callback returns with three LaneInformation objects. Since LaneInformation objects are always returned in the callback method in a left-to-right order, the first LaneInformation has a direction of LEFT and LaneInformation.getRecommendationState() returns a recommendation on whether the lane can be taken for the current route. If there isn't enough data to determine whether the lane is on or off-route, getRecommendationState() returns NOT_AVAILABLE.

School zone

@Override
public void onSchoolZoneAhead(@NonNull SchoolZoneNotification notification) {
  // distance to the road element with school zone
  int distance = notification.getDistance();
  // road element associated with this school zone
  RoadElement roadElement = notification.getRoadElement();
  // begin time, e.g. Monday 09:00
  Date timeBegin = notification.getSchoolZoneInfo().getTimeBegin();
  // end time, e.g. Monday 17:00
  Date timeEnd = notification.getSchoolZoneInfo().getTimeEnd();
  float speedLimit = notification.getSchoolZoneInfo().getSpeedLimit();
}

@Override
public void onSchoolZoneUpdated(@Nullable SchoolZoneInfo info) {
  if (info != null) {
    // user enters school zone
    float speedLimit = info.getSpeedLimit();
  } else {
    // user left school zone
  }
}
        

// Get road element from geo coordinate
RoadElement roadElement = RoadElement.getRoadElement(geoCoordinate, "MAC");
if (roadElement != null) {
  // Check whether road element has active school zone
  SchoolZoneInfo info = SchoolZoneRestrictionsChecker.getSchoolZoneInfo(roadElement);
  if (info != null) {
    // provided road element has school zone
  }

  // Check whether school zone is active at specific time
  SimpleDateFormat format = new SimpleDateFormat("HH:mm dd-MM-yyyy");
  Date date = format.parse("15:00 16-09-2020");
  SchoolZoneInfo infoWithSpecificDate = SchoolZoneRestrictionsChecker
    .getSchoolZoneInfo(roadElement, date);
  if (infoWithSpecificDate != null) {
    // school zone is active at provided time
  }
} else {
  // RoadElement is null either because there is no road at the provided location or map
  // data is not loaded. Use MapLoader API to download map area, or use road element from
  // another provider, e.g. from the calculated route.
}
        

Realistic View: 2D Signposts and Junction View

In addition to the data offered through the Lane Info feature, SDK for Android also offers image previews of signposts and junctions on certain highways. These two features together are known as Realistic View.

Figure 1. An Example of a 2D Signpost

Figure 2. An Example of a Junction View

The 2D Signpost feature provides images that illustrate road signposts. For example, as a user approaches a fork on a highway, your application can show a preview of the instruction signs above the highway. The Junction View feature provides images that illustrate road junctions. For example, as a user approaches a junction on a highway, your application can show the lanes near the junction with indicator arrows highlighting the correct lane to take. Signpost and junction view images are provided as SVG images through the following RealisticViewListener callback methods which occur just after the previous maneuver and before entering the junction:

• onRealisticViewShow(AspectRatio, Image, Image)
• onRealisticViewNextManeuver(AspectRatio, Image, Image)

Realistic view is disabled by default. To enable it, call NavigationManager.setRealisticViewMode(RealisticViewMode) and set the view mode to RealisticViewMode.DAY or RealisticViewMode.NIGHT. Next, register the desired image aspect ratios by using addRealisticViewAspectRatio(AspectRatio ratio). After adding your listener implementation, your application begins to receive the above event callbacks as HERE SDK arrives to a highway section that supports Realistic View.

The following is an example of onJunctionViewShow() and enabling realistic view:

// In the RealisticViewListener implementation
public void onRealisticViewShow(AspectRatio ratio, Image junction, Image signpost) {
  if (junction.getType() == Image.Type.SVG) {
    // full size is too big (will cover most of the screen), so cut the size in half
    Bitmap bmpImage = junction.getBitmap((int) (junction.getWidth() * 0.5),
        (int) (junction.getHeight() * 0.5));
    if (bmpImage != null) {
      //
      // show bmpImage on-screen
      //
    }
  }
  ...
}

navigationManager.setRealisticViewMode(NavigationManager.RealisticViewMode.DAY);
navigationManager.addRealisticViewAspectRatio(AspectRatio.AR_4x3);
navigationManager.addRealisticViewListener(
  new WeakReference<NavigationManager.RealisticViewListener>(viewListener));