Alternatives callouts and route line display (#4176)

* vk-navios-365-alternatives-callouts: fixed alternative routes callouts positioning and it's route line vanishing before the deviation point; fixed incorrect relative duration text in a callout; CHANGELOG updated

Author: Udumft

CHANGELOG.md

@@ -12,6 +12,7 @@
 
 * Added the `RouteController.prefersOnlineRoute` property, which lets you automatically switch from a route generated on the device to one generated by the Mapbox Directions API if the geometries match. Use `NavigationViewControllerDelegate.navigationViewController(_:didSwitchToCoincidentOnlineRoute:)`, `NavigationServiceDelegate.navigationService(_:didSwitchToCoincidentOnlineRoute:)`, `RouterDelegate.router(_:didSwitchToCoincidentOnlineRoute:)` or `.routeControllerDidSwitchToCoincidentOnlineRoute` notification to track such events. ([#4127](https://github.com/mapbox/mapbox-navigation-ios/pull/4127))
 * Added the `NavigationViewController(for:routeIndex:navigationOptions:)` initializer to start turn-by-turn navigation using map matching response. ([#4127](https://github.com/mapbox/mapbox-navigation-ios/pull/4127))
+* Fixed an issue where continuous alternative route lines and their corresponding callouts were misplaced on long routes. ([#4176](https://github.com/mapbox/mapbox-navigation-ios/pull/4176))
 
 ### Map
 

Sources/MapboxNavigation/NavigationMapView+VanishingRouteLine.swift

@@ -122,6 +122,23 @@ extension NavigationMapView {
         routeRemainingDistancesIndex = allPoints - allRemainingPoints
     }
 
+    func calculateGranularDistanceOffset(_ coordinates: [CLLocationCoordinate2D], splitPoint: CLLocationCoordinate2D) -> Double? {
+        if coordinates.isEmpty { return nil }
+        var distance = 0.0
+        var closestError = Double.greatestFiniteMagnitude
+        var pointDistance: Double? = nil
+        for index in stride(from: coordinates.count - 1, to: 0, by: -1) {
+            let curr = coordinates[index]
+            let prev = coordinates[index - 1]
+            distance += curr.projectedDistance(to: prev)
+            if curr.distance(to: splitPoint) < closestError {
+                pointDistance = distance
+                closestError = curr.distance(to: splitPoint)
+            }
+        }
+        return pointDistance.map { (distance - $0) / distance }
+    }
+    
     func calculateGranularDistances(_ coordinates: [CLLocationCoordinate2D]) -> RouteLineGranularDistances? {
         if coordinates.isEmpty { return nil }
         var distance = 0.0

Sources/MapboxNavigation/NavigationMapView.swift

@@ -303,12 +303,14 @@ open class NavigationMapView: UIView {
             }
         }
 
-        continuousAlternatives?.forEach { routeAlternative in
-            guard let route = routeAlternative.indexedRouteResponse.currentRoute else {
+        guard let continuousAlternatives = continuousAlternatives else { return }
+        for (index, routeAlternative) in continuousAlternatives.enumerated() {
+            guard let route = routeAlternative.indexedRouteResponse.currentRoute,
+                  alternativesRouteLineDeviationOffsets?.count ?? 0 > index,
+                  let offset = alternativesRouteLineDeviationOffsets?[index] else {
                 return
             }
 
-            let offset = (route.distance - routeAlternative.infoFromDeviationPoint.distance) / route.distance
             parentLayerIdentifier = addRouteLayer(route,
                                                   below: parentLayerIdentifier,
                                                   isMainRoute: false,
@@ -1152,14 +1154,11 @@ open class NavigationMapView: UIView {
         var features = [Turf.Feature]()
 
         for (index, alternativeRoute) in routes.enumerated() {
-            guard let routeShape = alternativeRoute.indexedRouteResponse.currentRoute?.shape else { return }
-            
-            var annotationCoordinate: LocationCoordinate2D!
-            if let mainRoute = self.routes?.first {
-                let offset = mainRoute.distance - alternativeRoute.infoFromDeviationPoint.distance + continuousAlternativeDurationAnnotationOffset
-                annotationCoordinate = routeShape.indexedCoordinateFromStart(distance: offset)?.coordinate
-            } else {
-                annotationCoordinate = routeShape.indexedCoordinateFromStart(distance: alternativeRoute.infoFromOrigin.distance - alternativeRoute.infoFromDeviationPoint.distance + continuousAlternativeDurationAnnotationOffset)?.coordinate
+            guard let routeShape = alternativeRoute.indexedRouteResponse.currentRoute?.shape,
+                  let annotationCoordinate = routeShape.indexedCoordinateFromStart(distance: alternativeRoute.infoFromOrigin.distance
+                                                                                   - alternativeRoute.infoFromDeviationPoint.distance
+                                                                                   + continuousAlternativeDurationAnnotationOffset)?.coordinate else {
+                return
             }
 
             // Form the appropriate text string for the annotation.
@@ -1693,7 +1692,19 @@ open class NavigationMapView: UIView {
     // MARK: Map Rendering and Observing
 
     var routes: [Route]?
-    var continuousAlternatives: [AlternativeRoute]?
+    var continuousAlternatives: [AlternativeRoute]? {
+        didSet {
+            alternativesRouteLineDeviationOffsets = continuousAlternatives?.map {
+                guard let coordinates = $0.indexedRouteResponse.currentRoute?.shape?.coordinates,
+                      let projectedOffset = calculateGranularDistanceOffset(coordinates,
+                                                                            splitPoint: $0.alternativeRouteIntersection.location) else {
+                    return 0.0
+                }
+                return projectedOffset
+            }
+        }
+    }
+    var alternativesRouteLineDeviationOffsets: [Double]?
     var routePoints: RoutePoints?
     var routeLineGranularDistances: RouteLineGranularDistances?
     var routeRemainingDistancesIndex: Int?