private WorldPoint PollGps()
{
WorldPoint point = new WorldPoint();
if (CheckForGps())
{
int interval = PollingInterval;
if (interval <= 0)
{
interval = 5000;
}
Gps.GpsPosition pos = gps.GetPosition(new TimeSpan(0, 0, 0, 0, interval));
if (pos != null && pos.LongitudeValid && pos.LatitudeValid &&
pos.Latitude != 0 && pos.Longitude != 0)
{
point.Latitude = pos.Latitude;
point.Longitude = pos.Longitude;
if (pos.SeaLevelAltitudeValid)
{
point.Altitude = pos.SeaLevelAltitude;
}
else
{
point.Altitude = null;
}
point.FixTime = pos.Time;
}
}
return(point);
}
/// <summary>
/// Get the position reported by the GPS receiver that is no older than
/// the maxAge passed in
/// </summary>
/// <param name="maxAge">Max age of the gps position data that you want back.
/// If there is no data within the required age, null is returned.
/// if maxAge == TimeSpan.Zero, then the age of the data is ignored</param>
/// <returns>GpsPosition class with all the position details</returns>
internal GpsPosition GetPosition(TimeSpan maxAge)
{
GpsPosition gpsPosition = null;
if (Opened)
{
// allocate the necessary memory on the native side. We have a class (GpsPosition) that
// has the same memory layout as its native counterpart
IntPtr ptr = Utils.LocalAlloc(Marshal.SizeOf(typeof(GpsPosition)));
// fill in the required fields
gpsPosition = new GpsPosition();
gpsPosition.dwVersion = 1;
gpsPosition.dwSize = Marshal.SizeOf(typeof(GpsPosition));
// Marshal our data to the native pointer we allocated.
Marshal.StructureToPtr(gpsPosition, ptr, false);
// call native method passing in our native buffer
int result = GPSGetPosition(gpsHandle, ptr, 500000, 0);
if (result == 0)
{
// native call succeeded, marshal native data to our managed data
gpsPosition = (GpsPosition)Marshal.PtrToStructure(ptr, typeof(GpsPosition));
if (maxAge != TimeSpan.Zero)
{
// check to see if the data is recent enough.
if (!gpsPosition.TimeValid || DateTime.Now - maxAge > gpsPosition.Time)
{
gpsPosition = null;
}
}
}
// free our native memory
Utils.LocalFree(ptr);
}
return(gpsPosition);
}
public LocationChangedEventArgs(GpsPosition position)
{
this.position = position;
}
