Add the ability to show specific route leg with color overriding

CHANGELOG.md

@@ -28,6 +28,7 @@
 * `NavigationMapView.highlightBuildings(at:in3D:)` was renamed to `NavigationMapView.highlightBuildings(at:in3D:completion:)`. ([#2827](https://github.com/mapbox/mapbox-navigation-ios/pull/2827))
 * Added the `NavigationMapView.showsCongestionForAlternativeRoutes` property to show congestion levels with different colors on alternative route lines. ([#2887](https://github.com/mapbox/mapbox-navigation-ios/pull/2887))
 * Added the `NavigationMapView.navigationMapView(_:didAdd:)` and `NavigationViewController.navigationViewController(_:didAdd:)` delegate methods, which will be called whenever final destination `PointAnnotation` is added to `NavigationMapView` or `NavigationViewController` respectively. ([#2961](https://github.com/mapbox/mapbox-navigation-ios/pull/2961))
+* Added the ability to show specific route leg with color overriding. When specifying the `legIndex` in `NavigationMapView.show(_:legIndex:)`, the route line for the specific route leg would show congestion colors, while other route legs would show `NavigationMapView.routeCasingColor` by default. If not specified, all the route legs would show congestion colors. During turn-by-turn navigation, the default specified route leg is the current route leg. The route leg colors could be overridden by `NavigationMapView.routeCasingColor` and the congestion colors. ([#2833](https://github.com/mapbox/mapbox-navigation-ios/pull/2833))
 
 ### Location tracking
 

Sources/MapboxNavigation/NavigationMapView+VanishingRouteLine.swift

@@ -208,7 +208,7 @@ extension NavigationMapView {
 
             let newFractionTraveled = self.preFractionTraveled + traveledDifference * timePassedInMilliseconds.truncatingRemainder(dividingBy: 1000) / 1000
 
-            let congestionSegments = routeProgress.route.congestionFeatures(roadClassesWithOverriddenCongestionLevels: self.roadClassesWithOverriddenCongestionLevels)
+            let congestionSegments = routeProgress.route.congestionFeatures(legIndex: self.currentLegIndex, roadClassesWithOverriddenCongestionLevels: self.roadClassesWithOverriddenCongestionLevels)
             let mainRouteLayerGradient = self.routeLineGradient(congestionSegments,
                                                                 fractionTraveled: newFractionTraveled)
             self.mapView.style.updateLayer(id: mainRouteLayerIdentifier, type: LineLayer.self) { (lineLayer) in
@@ -231,8 +231,12 @@ extension NavigationMapView {
             var minimumSegment: (Double, UIColor) = (Double.greatestFiniteMagnitude, .clear)
 
             for (index, feature) in congestionFeatures.enumerated() {
+                var associatedFeatureColor = routeCasingColor
                 let congestionLevel = feature.properties?[CongestionAttribute] as? String
-                let associatedCongestionColor = congestionColor(for: congestionLevel, isMain: isMain)
+                if let isCurrentLeg = feature.properties?[CurrentLegAttribute] as? Bool, isCurrentLeg {
+                    associatedFeatureColor = congestionColor(for: congestionLevel, isMain: isMain)
+                }
+
                 let lineString = feature.geometry.value as? LineString
                 guard let distance = lineString?.distance() else { return gradientStops }
 
@@ -242,10 +246,10 @@ extension NavigationMapView {
                     let segmentEndPercentTraveled = CGFloat(distanceTraveled / routeDistance)
                     let currentGradientStop = Double(segmentEndPercentTraveled.nextDown)
                     if currentGradientStop >= fractionTraveled {
-                        gradientStops[currentGradientStop] = associatedCongestionColor
+                        gradientStops[currentGradientStop] = associatedFeatureColor
 
                         if currentGradientStop < minimumSegment.0 {
-                            minimumSegment = (currentGradientStop, associatedCongestionColor)
+                            minimumSegment = (currentGradientStop, associatedFeatureColor)
                         }
 
                         if index + 1 < congestionFeatures.count {
@@ -264,10 +268,10 @@ extension NavigationMapView {
 
                 if index == congestionFeatures.endIndex - 1 {
                     let lastGradientStop: Double = 1.0
-                    gradientStops[lastGradientStop] = associatedCongestionColor
+                    gradientStops[lastGradientStop] = associatedFeatureColor
 
                     if lastGradientStop < minimumSegment.0 {
-                        minimumSegment = (lastGradientStop, associatedCongestionColor)
+                        minimumSegment = (lastGradientStop, associatedFeatureColor)
                     }
 
                     continue
@@ -277,10 +281,10 @@ extension NavigationMapView {
 
                 if Double(segmentStartPercentTraveled.nextUp) >= fractionTraveled {
                     let currentGradientStop = Double(segmentStartPercentTraveled.nextUp)
-                    gradientStops[currentGradientStop] = associatedCongestionColor
+                    gradientStops[currentGradientStop] = associatedFeatureColor
 
                     if currentGradientStop < minimumSegment.0 {
-                        minimumSegment = (currentGradientStop, associatedCongestionColor)
+                        minimumSegment = (currentGradientStop, associatedFeatureColor)
                     }
                 }
 
@@ -289,16 +293,20 @@ extension NavigationMapView {
                 let segmentEndPercentTraveled = CGFloat(distanceTraveled / routeDistance)
                 if Double(segmentEndPercentTraveled.nextDown) >= fractionTraveled {
                     let currentGradientStop = Double(segmentEndPercentTraveled.nextDown)
-                    gradientStops[currentGradientStop] = associatedCongestionColor
+                    gradientStops[currentGradientStop] = associatedFeatureColor
 
                     if currentGradientStop < minimumSegment.0 {
-                        minimumSegment = (currentGradientStop, associatedCongestionColor)
+                        minimumSegment = (currentGradientStop, associatedFeatureColor)
                     }
                 }
-                
+
                 if index + 1 < congestionFeatures.count && Double(segmentEndPercentTraveled.nextUp) >= fractionTraveled {
                     let currentGradientStop = Double(segmentEndPercentTraveled.nextUp)
-                    let currentColor = congestionColor(for: congestionFeatures[index + 1].properties?["congestion"] as? String, isMain: isMain)
+                    let nextCongestionLevel = congestionFeatures[index + 1].properties?[CongestionAttribute] as? String
+                    var currentColor = routeCasingColor
+                    if let isCurrentLeg = congestionFeatures[index + 1].properties?[CurrentLegAttribute] as? Bool, isCurrentLeg {
+                        currentColor = congestionColor(for: nextCongestionLevel, isMain: isMain)
+                    }
                     gradientStops[currentGradientStop] = currentColor
 
                     if currentGradientStop < minimumSegment.0 {

Sources/MapboxNavigation/NavigationMapView.swift

@@ -104,6 +104,7 @@ open class NavigationMapView: UIView {
     var fractionTraveled: Double = 0.0
     var preFractionTraveled: Double = 0.0
     var vanishingRouteLineUpdateTimer: Timer? = nil
+    var currentLegIndex: Int?
 
     var showsRoute: Bool {
         get {
@@ -393,19 +394,19 @@ open class NavigationMapView: UIView {
      - parameter routes: List of `Route` objects, which will be shown on `MapView`.
      - parameter legIndex: Index, which will be used to highlight specific `RouteLeg` on main route.
      */
-    // TODO: Add ability to handle legIndex.
-    public func show(_ routes: [Route], legIndex: Int = 0) {
+    public func show(_ routes: [Route], legIndex: Int? = nil) {
         removeRoutes()
 
         self.routes = routes
+        currentLegIndex = legIndex
 
         var parentLayerIdentifier: String? = nil
         for (index, route) in routes.enumerated() {
             if index == 0, routeLineTracksTraversal {
                 initPrimaryRoutePoints(route: route)
             }
 
-            parentLayerIdentifier = addRouteLayer(route, below: parentLayerIdentifier, isMainRoute: index == 0)
+            parentLayerIdentifier = addRouteLayer(route, below: parentLayerIdentifier, isMainRoute: index == 0, legIndex: legIndex)
             parentLayerIdentifier = addRouteCasingLayer(route, below: parentLayerIdentifier, isMainRoute: index == 0)
         }
     }
@@ -436,7 +437,7 @@ open class NavigationMapView: UIView {
         updateUserCourseView(CLLocation(latitude: coordinate.latitude, longitude: coordinate.longitude))
     }
 
-    @discardableResult func addRouteLayer(_ route: Route, below parentLayerIndentifier: String? = nil, isMainRoute: Bool = true) -> String? {
+    @discardableResult func addRouteLayer(_ route: Route, below parentLayerIndentifier: String? = nil, isMainRoute: Bool = true, legIndex: Int? = nil) -> String? {
         guard let shape = route.shape else { return nil }
 
         let geoJSONSource = self.geoJSONSource(delegate?.navigationMapView(self, casingShapeFor: route) ?? shape)
@@ -458,7 +459,8 @@ open class NavigationMapView: UIView {
 
             // TODO: Verify that `isAlternativeRoute` parameter usage is needed.
             if isMainRoute {
-                let gradientStops = routeLineGradient(route.congestionFeatures(roadClassesWithOverriddenCongestionLevels: roadClassesWithOverriddenCongestionLevels),
+                let congestionFeatures = route.congestionFeatures(legIndex: legIndex, roadClassesWithOverriddenCongestionLevels: roadClassesWithOverriddenCongestionLevels)
+                let gradientStops = routeLineGradient(congestionFeatures,
                                                       fractionTraveled: routeLineTracksTraversal ? fractionTraveled : 0.0)
                 lineLayer?.paint?.lineGradient = .expression((Expression.routeLineGradientExpression(gradientStops)))
             } else {

Sources/MapboxNavigation/Route.swift

@@ -71,7 +71,7 @@ extension Route {
                     feature.properties = [
                         CongestionAttribute: String(describing: congestionSegment.1),
                         "isAlternativeRoute": isAlternativeRoute,
-                        CurrentLegAttribute: (legIndex != nil) ? index == legIndex : index == 0
+                        CurrentLegAttribute: (legIndex != nil) ? index == legIndex : true
                     ]
 
                     return feature
@@ -80,7 +80,7 @@ extension Route {
                 var feature = Feature(LineString(shape.coordinates))
                 feature.properties = [
                     "isAlternativeRoute": isAlternativeRoute,
-                    CurrentLegAttribute: (legIndex != nil) ? index == legIndex : index == 0
+                    CurrentLegAttribute: (legIndex != nil) ? index == legIndex : true
                 ]
                 legFeatures = [feature]
             }