/// <summary>
/// See interface docs.
/// </summary>
public void ResetCoordinates()
{
lock (this) {
LatestCoordinateTime = default(DateTime);
FullCoordinates.Clear();
ShortCoordinates.Clear();
FirstCoordinateChanged = 0;
LastCoordinateChanged = 0;
}
}
/// <summary>
/// See interface docs.
/// </summary>
/// <param name="utcNow"></param>
/// <param name="shortCoordinateSeconds"></param>
public void UpdateCoordinates(DateTime utcNow, int shortCoordinateSeconds)
{
if (Latitude != null && Longitude != null)
{
var nowTick = utcNow.Ticks;
var lastFullCoordinate = FullCoordinates.Count == 0 ? null : FullCoordinates[FullCoordinates.Count - 1];
var secondLastFullCoordinate = FullCoordinates.Count < 2 ? null : FullCoordinates[FullCoordinates.Count - 2];
if (lastFullCoordinate == null || Latitude != lastFullCoordinate.Latitude || Longitude != lastFullCoordinate.Longitude)
{
PositionTime = utcNow;
// Check to see whether the aircraft appears to be moving impossibly fast and, if it is, reset its trail. Do this even if
// the gap between this message and the last is below the threshold for adding to the trails.
if (lastFullCoordinate != null)
{
var distance = GreatCircleMaths.Distance(lastFullCoordinate.Latitude, lastFullCoordinate.Longitude, Latitude, Longitude);
if (distance > _ResetCoordinatesDistance)
{
var fastestTime = _ResetCoordinatesTime * (distance / _ResetCoordinatesDistance);
if (nowTick - lastFullCoordinate.Tick < fastestTime)
{
ResetCoordinates();
}
}
}
// Only update the trails if more than one second has elapsed since the last position update
long lastUpdateTick = lastFullCoordinate == null ? 0 : lastFullCoordinate.Tick;
if (nowTick - lastUpdateTick >= TicksPerSecond)
{
var coordinate = new Coordinate(DataVersion, nowTick, (float)Latitude, (float)Longitude, Track);
if (FullCoordinates.Count > 1 &&
(int)(lastFullCoordinate.Heading.GetValueOrDefault() + 0.5f) == (int)(Track.GetValueOrDefault() + 0.5f) &&
(int)(secondLastFullCoordinate.Heading.GetValueOrDefault() + 0.5f) == (int)(Track.GetValueOrDefault() + 0.5f))
{
FullCoordinates[FullCoordinates.Count - 1] = coordinate;
}
else
{
FullCoordinates.Add(coordinate);
}
long earliestAllowable = nowTick - (TicksPerSecond * shortCoordinateSeconds);
var firstAllowableIndex = ShortCoordinates.FindIndex(c => c.Tick >= earliestAllowable);
if (firstAllowableIndex == -1)
{
ShortCoordinates.Clear();
}
else if (firstAllowableIndex > 0)
{
ShortCoordinates.RemoveRange(0, firstAllowableIndex);
}
ShortCoordinates.Add(coordinate);
if (FirstCoordinateChanged == 0)
{
FirstCoordinateChanged = DataVersion;
}
LastCoordinateChanged = DataVersion;
LatestCoordinateTime = utcNow;
}
}
}
}