System.TimeZone.CalculateUtcOffset C# (CSharp) Méthode

        internal static TimeSpan CalculateUtcOffset(DateTime time, DaylightTime daylightTimes) {
            if (daylightTimes==null) {
                return TimeSpan.Zero;
            }
            DateTimeKind kind = time.Kind;
            if (kind == DateTimeKind.Utc) {
                return TimeSpan.Zero;
            }

            DateTime startTime;
            DateTime endTime;

            // startTime and endTime represent the period from either the start of DST to the end and includes the 
            // potentially overlapped times
            startTime = daylightTimes.Start + daylightTimes.Delta;
            endTime = daylightTimes.End;
            
            // For normal time zones, the ambiguous hour is the last hour of daylight saving when you wind the 
            // clock back. It is theoretically possible to have a positive delta, (which would really be daylight
            // reduction time), where you would have to wind the clock back in the begnning.
            DateTime ambiguousStart;
            DateTime ambiguousEnd;            
            if (daylightTimes.Delta.Ticks > 0) {
                ambiguousStart = endTime - daylightTimes.Delta;
                ambiguousEnd = endTime;
            } else {
                ambiguousStart = startTime;
                ambiguousEnd = startTime - daylightTimes.Delta;
            }

            Boolean isDst = false;
            if (startTime > endTime) {
                // In southern hemisphere, the daylight saving time starts later in the year, and ends in the beginning of next year.
                // Note, the summer in the southern hemisphere begins late in the year.
                if (time >= startTime || time < endTime) {
                    isDst = true;
                }
            }
            else if (time>=startTime && time < endTime) {
                // In northern hemisphere, the daylight saving time starts in the middle of the year.
                isDst = true;
            }
            
            // If this date was previously converted from a UTC date and we were able to detect that the local
            // DateTime would be ambiguous, this data is stored in the DateTime to resolve this ambiguity. 
            if (isDst && time >= ambiguousStart && time < ambiguousEnd) {
                isDst = time.IsAmbiguousDaylightSavingTime();
            }
           
            if (isDst) {
                return daylightTimes.Delta;
            }
            return TimeSpan.Zero;
        }
    }

 // Token: 0x06000CF3 RID: 3315 RVA: 0x0002795C File Offset: 0x00025B5C
 public override TimeSpan GetUtcOffset(DateTime time)
 {
     if (time.Kind == DateTimeKind.Utc)
     {
         return(TimeSpan.Zero);
     }
     return(new TimeSpan(TimeZone.CalculateUtcOffset(time, this.GetDaylightChanges(time.Year)).Ticks + this.m_ticksOffset));
 }