Don't continual reroute user if standing still, allow user time to get to route start

MapboxNavigation/Constants.swift

@@ -51,6 +51,12 @@ public var RouteControllerHighAlertInterval: TimeInterval = 15
 public var RouteControllerManeuverZoneRadius: CLLocationDistance = 40
 
 
+/*
+ Maximum number of seconds the user can travel away from the start of the route before rerouting occurs
+*/
+public var MaxSecondsSpentTravelingAwayFromStartOfRoute: TimeInterval = 3
+
+
 /*
  Distance in meters for the minimum length of a step for giving a `medium` alert.
 */

MapboxNavigation/RouteController.swift

@@ -9,6 +9,10 @@ import MapboxDirections
 @objc(MBRouteController)
 open class RouteController: NSObject {
 
+    var lastUserDistanceToStartOfRoute = Double.infinity
+
+    var lastTimeStampSpentMovingAwayFromStart = Date()
+
     /*
      Monitor users location along route.
 
@@ -87,13 +91,6 @@ extension RouteController: CLLocationManagerDelegate {
             return
         }
 
-        guard userIsOnRoute(location) else {
-            NotificationCenter.default.post(name: RouteControllerShouldReroute, object: self, userInfo: [
-                RouteControllerNotificationShouldRerouteKey: location
-                ])
-            return
-        }
-
         // Notify observers if the step’s remaining distance has changed.
         let currentStepProgress = routeProgress.currentLegProgress.currentStepProgress
         let currentStep = currentStepProgress.step
@@ -110,9 +107,48 @@ extension RouteController: CLLocationManagerDelegate {
             }
         }
 
+        let step = routeProgress.currentLegProgress.currentStepProgress.step
+        if step.maneuverType == .depart && !userIsOnRoute(location) {
+
+            guard let userSnappedDistanceToClosestCoordinate = closestCoordinate(on: step.coordinates!, to: location.coordinate)?.distance else {
+                return
+            }
+
+            // Give the user x seconds of moving away from the start of the route before rerouting
+            guard Date().timeIntervalSince(lastTimeStampSpentMovingAwayFromStart) > MaxSecondsSpentTravelingAwayFromStartOfRoute else {
+                lastUserDistanceToStartOfRoute = userSnappedDistanceToClosestCoordinate
+                return
+            }
+
+            // Don't check `userIsOnRoute` if the user has not moved
+            guard userSnappedDistanceToClosestCoordinate != lastUserDistanceToStartOfRoute else {
+                lastUserDistanceToStartOfRoute = userSnappedDistanceToClosestCoordinate
+                return
+            }
+
+            if userSnappedDistanceToClosestCoordinate > lastUserDistanceToStartOfRoute {
+                lastTimeStampSpentMovingAwayFromStart = location.timestamp
+            }
+
+            lastUserDistanceToStartOfRoute = userSnappedDistanceToClosestCoordinate
+        }
+
+        guard userIsOnRoute(location) else {
+            resetStartCounter()
+            NotificationCenter.default.post(name: RouteControllerShouldReroute, object: self, userInfo: [
+                RouteControllerNotificationShouldRerouteKey: location
+                ])
+            return
+        }
+
         monitorStepProgress(location)
     }
 
+    func resetStartCounter() {
+        lastTimeStampSpentMovingAwayFromStart = Date()
+        lastUserDistanceToStartOfRoute = Double.infinity
+    }
+
     public func userIsOnRoute(_ location: CLLocation) -> Bool {
         // Find future location of user
         let metersInFrontOfUser = location.speed * RouteControllerDeadReckoningTimeInterval

MapboxNavigationTests/MapboxNavigationTests.swift

@@ -62,16 +62,22 @@ class MapboxNavigationTests: XCTestCase {
     func testShouldReroute() {
         let navigation = RouteController(route: route)
         navigation.resume()
-        let reroutePoint = CLLocation(coordinate: CLLocationCoordinate2D(latitude: 38, longitude: -123), altitude: 1, horizontalAccuracy: 1, verticalAccuracy: 1, course: 0, speed: 10, timestamp: Date())
+
+        let reroutePoint1 = CLLocation(latitude: 38, longitude: -123)
+        let reroutePoint2 = CLLocation(latitude: 38, longitude: -124)
 
         self.expectation(forNotification: RouteControllerShouldReroute.rawValue, object: navigation) { (notification) -> Bool in
             XCTAssertEqual(notification.userInfo?.count, 1)
 
             let location = notification.userInfo![RouteControllerNotificationShouldRerouteKey] as? CLLocation
-            return location == reroutePoint
+            return location == reroutePoint2
         }
 
-        navigation.locationManager(navigation.locationManager, didUpdateLocations: [reroutePoint])
+        navigation.locationManager(navigation.locationManager, didUpdateLocations: [reroutePoint1])
+
+        _ = Timer.scheduledTimer(withTimeInterval: 5, repeats: false) { timer in
+            navigation.locationManager(navigation.locationManager, didUpdateLocations: [reroutePoint2])
+        }
 
         waitForExpectations(timeout: waitForInterval)
     }