Create camera animation from time between updates (#753)

* Create camera animation from time between updates

* Fixup checkstyle

* Updates per review

libandroid-navigation-ui/src/main/java/com/mapbox/services/android/navigation/ui/v5/camera/NavigationCamera.java

@@ -1,6 +1,7 @@
 package com.mapbox.services.android.navigation.ui.v5.camera;
 
 import android.location.Location;
+import android.os.SystemClock;
 import android.support.annotation.NonNull;
 
 import com.mapbox.api.directions.v5.models.DirectionsRoute;
@@ -25,10 +26,13 @@
  */
 public class NavigationCamera implements ProgressChangeListener {
 
+  private static final long MAX_ANIMATION_DURATION_MS = 1500;
+
   private MapboxMap mapboxMap;
   private MapboxNavigation navigation;
   private RouteInformation currentRouteInformation;
   private boolean trackingEnabled = true;
+  private long locationUpdateTimestamp;
 
   /**
    * Creates an instance of {@link NavigationCamera}.
@@ -184,7 +188,8 @@ private void updateMapCameraPosition(CameraPosition position, MapboxMap.Cancelab
    * @param position to which the camera should animate
    */
   private void easeMapCameraPosition(CameraPosition position) {
-    mapboxMap.easeCamera(CameraUpdateFactory.newCameraPosition(position), 1000, false, null);
+    mapboxMap.easeCamera(CameraUpdateFactory.newCameraPosition(position),
+      obtainLocationUpdateDuration(), false, null);
   }
 
   /**
@@ -252,4 +257,11 @@ private void animateCameraFromLocation(RouteInformation routeInformation) {
 
     easeMapCameraPosition(position);
   }
+
+  private int obtainLocationUpdateDuration() {
+    long previousUpdateTimeStamp = locationUpdateTimestamp;
+    locationUpdateTimestamp = SystemClock.elapsedRealtime();
+    long duration = locationUpdateTimestamp - previousUpdateTimeStamp;
+    return (int) (duration < MAX_ANIMATION_DURATION_MS ? duration : MAX_ANIMATION_DURATION_MS);
+  }
 }