/// <summary>
/// Converts a local time of the source time-zone to a Utc time
/// </summary>
/// <param name="source">The source time-zone</param>
/// <param name="sourceLocalTime">The local time in the source time-zone</param>
/// <returns>The Utc time that is equivalent to the local time in the source time-zone.</returns>
public static DateTime ToUniversalTime(TimeZoneInfo source, DateTime sourceLocalTime)
{
// Min and Max value are treated as 'special' dates that should never need converted.
if (sourceLocalTime == DateTime.MinValue || sourceLocalTime == DateTime.MaxValue)
{
return(DateTime.SpecifyKind(sourceLocalTime, DateTimeKind.Utc));
}
//first we must determine if the specified local time is during the daylight saving
//time period. If it is, then we add the Bias and Daylight bias to the value, otherwise
//we add the Bias and Standard bias (I believe that StandardBias is always 0)
DateTime utcTime;
if (source.IsDaylightSavingTime(sourceLocalTime))
{
utcTime = sourceLocalTime.AddMinutes(source.Bias + source.DaylightBias);
}
else
{
utcTime = sourceLocalTime.AddMinutes(source.Bias + source.StandardBias);
}
return(DateTime.SpecifyKind(utcTime, DateTimeKind.Utc));
}
/// <summary>
/// Converts the UtcTime to the local time of the destination time-zone.
/// </summary>
/// <param name="destination">The destination time-zone</param>
/// <param name="utcTime">Utc time that is to be converted to the local time of
/// the destination time-zone.</param>
/// <returns>DateTime that represents the local time in the destination time-zone</returns>
public static DateTime ToLocalTime(TimeZoneInfo destination, DateTime utcTime)
{
// Min and Max value are treated as 'special' dates that should never need converted.
if (utcTime == DateTime.MinValue || utcTime == DateTime.MaxValue)
{
return(DateTime.SpecifyKind(utcTime, DateTimeKind.Local));
}
//first we must convert the utcTime to the local time without any regard to the
//daylight saving issues. We'll deal with that next
DateTime localTime = utcTime.AddMinutes(-destination.Bias);
// Need to set it to kind of Local, because System.TimeZone.IsDaylightSavingTime
// will return false if the time passed into it is not Local.
localTime = DateTime.SpecifyKind(localTime, DateTimeKind.Local);
//now we must determine if the specified local time is during the daylight saving
//time period. If it is, then we add the Bias and Daylight bias to the value, otherwise
//we add the Bias and Standard bias (I believe that StandardBias is always 0)
if (destination.IsDaylightSavingTime(localTime))
{
return(localTime.AddMinutes(-destination.DaylightBias));
}
else
{
return(localTime.AddMinutes(-destination.StandardBias));
}
}
