Route updates and rerouting
The Navigation SDK has built-in logic to make sure your users are on the best route as traffic conditions change or the user goes off route. This includes:
- Off-route detection to get users back on track if they have strayed from the current route.
- Route refresh to make sure the current route is still a viable route.
- Alternative routes to offer users alternative routes as available.
Off-route detection
The Navigation SDK detects when a device strayed from a route it was navigating. When a device is determined to be off route, the SDK automatically requests a redirected route by default. If the reroute request is successful, the new route will be delivered via RoutesObserver
.
If you want to customize your application's behavior when a user goes off route, you can observe the event using OffRouteObserver
or control what triggers an off-route event using NavigationRerouteController
.
Observe off-route events
The OffRouteObserver
interface provides a boolean whenever the Navigation SDK is in turn-by-turn navigation and is off route. When the device is determined to be off route, the Navigation SDK will automatically request a new route.
To listen for changes in the off-route state, create the OffRouteObserver
interface object:
val offRouteObserver = object : OffRouteObserver {
override fun onOffRouteStateChanged(offRoute: Boolean) {
// do something when the off route state changes
}
}
Then, register the OffRouteObserver
object with your already-instantiated MapboxNavigation
object.
override fun onStart() {
super.onStart()
mapView.onStart()
mapboxNavigation.registerOffRouteObserver(offRouteObserver)
}
Don’t forget to unregister the OffRouteObserver
interface:
override fun onStop() {
super.onStop()
mapView.onStop()
mapboxNavigation.unregisterOffRouteObserver(offRouteObserver)
}
Customize off-route triggers
To customize the conditions that trigger off-route conditions, you can provide a custom NavigationRerouteController
:
mapboxNavigation.setRerouteController(object : NavigationRerouteController {
// set the conditions that will trigger off-route conditions
})
Or, you can disable off-route detection entirely by passing null
:
mapboxNavigation.setRerouteController(null)
Observe changes to reroute states
Whether you are using the default triggers or a custom NavigationRerouteController
, the controller produces reroute state updates that can be listened to with the RerouteStateObserver
:
mapboxNavigation.getRerouteController()?.registerRerouteStateObserver(object : RerouteStateObserver {
// do something when the reroute state changes
})
NavigationRerouteController
if you would like to retry the reroute request if the first request fails.Route refresh
Traffic conditions along a route can change while you're navigating, causing the initial route information to be out of date. The Navigation SDK can refresh a route to make sure your users stay on track as they progress along a route.
Route refresh interval is configured with the RouteRefreshOptions.intervalMillis
parameter. By default, the SDK will refresh the current route every five minutes, and if the refresh request is successful, an updated route will be delivered via RoutesObserver
.
RouteOptions.enableRefresh
is true.Alternative routes
Traffic conditions along a route can change while you're navigating, causing the initial route to no longer be as fast as it was when you departed. The Navigation SDK can provide alternative routes to make sure your users are on the best route.
The Navigation SDK is continuously looking for route alternatives and triggers request based on two internal conditions:
- Passing a fork point with an existing alternative route - the existing alternative becomes invalid and the Navigation SDK requests new alternative routes.
- There are no tracked alternative routes - the Navigation SDK requests alternatives with the interval
RouteAlternativesOptions.intervalMillis
until it gets successful response with valid alternatives, default interval is 5 minutes.
New routes will be delivered via NavigationRouteAlternativesObserver
.
NavigationRouteAlternativesObserver
.Observe alternative route events
The Navigation SDK's NavigationRouteAlternativesObserver
interface alerts you when the Navigation SDK detects alternative routes. The observer is also called when user passes the fork intersection with an alternative route, making the alternative invalid and ready to be cleaned up. In the code snippet below:
routeProgress
is the current route's progress.alternatives
is a list of alternative routes, can be empty.routerOrigin
describes which router was used to get alternative routes.
val routeAlternativesObserver = object : NavigationRouteAlternativesObserver {
override fun onRouteAlternatives(routeProgress: RouteProgress, alternatives: List<NavigationRoute>, routerOrigin: RouterOrigin)
{
val newRoutes = mutableListOf<NavigationRoute>().apply {
add(routeProgress.navigationRoute)
addAll(alternatives)
}
mapboxNavigation.setNavigationRoutes(newRoutes)
}
override fun onRouteAlternativesError(error: RouteAlternativesError) {
}
}
Attach the NavigationRouteAlternativesObserver
object to your already-instantiated MapboxNavigation
object.
mapboxNavigation.registerRouteAlternativesObserver(routeAlternativesObserver)
You can compare alternative routes with the original one to choose the route to navigate on (for example, route.duration
can be used to find the fastest one). If you want to use one of the alternative routes, pass the list to MapboxNavigation
with mapboxNavigation.setNavigationRoutes(routes)
.
Don’t forget to unregister the NavigationRouteAlternativesObserver
interface to stop requesting alternative routes:
override fun onStop() {
super.onStop()
mapView.onStop()
mapboxNavigation.unregisterRouteAlternativesObserver(routeAlternativesObserver)
}
Trigger an alternative route
The SDK requests for alternative routes automatically, but you can also trigger an alternative route request at any given time using requestAlternativeRoutes()
. This can be helpful if you want a specific event or user action to trigger an alternative route request outside the regular interval defined by RouteAlternativesOptions.intervalMillis
.
mapboxNavigation.requestAlternativeRoutes()
Updated route lines on the map
When a reroute event occurs it's important the route line on the map gets updated to communicate the route change to the user.
It's common to have a RoutesObserver
registered in an activity or fragment. This observer gets called when the route has changed. You can update the route line in this observer to keep the line on the map in sync with the route used by core navigation.
private val routesObserver: RoutesObserver = RoutesObserver { routes ->
val routeLines = routes.map { RouteLine(it, null) }
routeLineApi.setRoutes(routeLines) { result ->
routeLineView.renderRouteDrawData(mapStyle, result)
}
}
If you're not using a RoutesObserver
in this way, another way to update the map is by using a RouteProgressObserver
. The RouteProgress
has a reference to the route being navigated.
val routeProgressObserver = RouteProgressObserver { routeProgress ->
val routeLines = routes.map { RouteLine(it, null) }
routeLineApi.setRoutes(routeLines) { result ->
routeLineView.renderRouteDrawData(mapStyle, result)
}
}