/// <summary>
/// Determines if the is Time Zone currently on Daylight Saving Time
/// </summary>
/// <param name="TZIData"></param>
/// <returns></returns>
private bool IsOnDST(TZI TZIData)
{
// Get the current time (GMT)
DateTime currentDate = DateTime.UtcNow;
// Get the end date for the current year and convert to GMT (important!)
DateTime standardDate = ConvertSystemTime(TZIData.StandardDate, currentDate.Year);
DateTime standardDateGMT = standardDate.AddMinutes(TZIData.DaylightBias + TZIData.Bias);
// Determine the current (or next) end date
if (currentDate > standardDateGMT)
{
standardDate = ConvertSystemTime(TZIData.StandardDate, currentDate.Year+1);
}
// Determine the current (or next) start date
DateTime daylightDate;
if (TZIData.StandardDate.wMonth > TZIData.DaylightDate.wMonth)
{
// Northern hemisphere
daylightDate = ConvertSystemTime(TZIData.DaylightDate, standardDate.Year);
}
else
{
// Southern hemisphere
daylightDate = ConvertSystemTime(TZIData.DaylightDate, standardDate.Year-1);
}
DateTime daylightDateGMT = daylightDate.AddMinutes(TZIData.StandardBias + TZIData.Bias);
return daylightDateGMT <= currentDate && currentDate <= standardDateGMT;
}
/// <summary>
/// Decodes the Time Zone Information structure from the byte array
/// </summary>
/// <param name="bytes"></param>
/// <returns></returns>
private TZI GetTZI(byte[] bytes)
{
if (bytes == null || bytes.Length < Marshal.SizeOf(typeof(TZI)))
throw new Exception("TZI byte array is not a valid size");
TZI currentTZI = new TZI();
GCHandle handle = GCHandle.Alloc(bytes, GCHandleType.Pinned);
IntPtr buffer = handle.AddrOfPinnedObject();
currentTZI = (TZI) Marshal.PtrToStructure (buffer, typeof(TZI));
handle.Free();
return currentTZI;
}
