Track point is now removed after its expiry and fades after the boat has stopped Story [758]

src/main/java/seng302/Model/BoatInRace.java

@@ -260,9 +260,13 @@ public class BoatInRace extends Boat {
 
     public boolean addTrackPoint(GPSCoordinate coordinate) {
         Boolean added = System.currentTimeMillis() >= nextValidTime;
+        long currentTime = System.currentTimeMillis();
         if (added && this.started) {
-            nextValidTime = System.currentTimeMillis() + TRACK_POINT_TIME_INTERVAL;
+            nextValidTime = currentTime + TRACK_POINT_TIME_INTERVAL;
-            track.add(new TrackPoint(coordinate, System.currentTimeMillis(), TRACK_POINT_LIMIT*TRACK_POINT_TIME_INTERVAL));
+            track.add(new TrackPoint(coordinate, currentTime, TRACK_POINT_LIMIT * TRACK_POINT_TIME_INTERVAL));
+        }
+        if (track.size() > 0 && track.element().getTimeAdded() + TRACK_POINT_LIMIT * TRACK_POINT_TIME_INTERVAL <= currentTime) {
+            track.remove();
         }
         return added;
     }

src/main/java/seng302/Model/TrackPoint.java

@@ -23,6 +23,13 @@ public class TrackPoint {
     }
 
     public double getAlpha() {
-        return Double.max(minAlpha,1.0 - (double)(System.currentTimeMillis() - timeAdded)/expiry);
+        if (System.currentTimeMillis() >= timeAdded + expiry) {
+            return 0;
+        }
+        return Double.max(minAlpha,1.0 - (double)(System.currentTimeMillis() - timeAdded) / expiry);
+    }
+
+    public long getTimeAdded() {
+        return timeAdded;
     }
 }