/// <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>
public 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 dwMaxAge;
if (maxAge == TimeSpan.Zero)
{
dwMaxAge = Int32.MaxValue;
}
else
{
dwMaxAge = (int)maxAge.TotalMilliseconds;
}
if (GPSGetPosition(gpsHandle, ptr, dwMaxAge, 0) == 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.UtcNow - maxAge > gpsPosition.Time)
{
gpsPosition = null;
}
}
}
// free our native memory
Utils.LocalFree(ptr);
}
return(gpsPosition);
}
public LocationChangedEventArgs(GpsPosition position)
{
this.position = position;
}
