public DateTime GetLocalTime(string timeZoneKey, DateTime utc)
{
// Convert to Win32 SYSTEMTIME
SYSTEMTIME utcSysTime = new SYSTEMTIME
{
wYear = (ushort)utc.Year,
wMonth = (ushort)utc.Month,
wDay = (ushort)utc.Day,
wHour = (ushort)utc.Hour,
wMinute = (ushort)utc.Minute,
wSecond = (ushort)utc.Second,
wMilliseconds = (ushort)utc.Millisecond
};
// Convert to local time
DYNAMIC_TIME_ZONE_INFORMATION dtzi = dynamicTzis[timeZoneKey];
TIME_ZONE_INFORMATION tzi = new TIME_ZONE_INFORMATION();
GetTimeZoneInformationForYear((ushort)utc.Year, ref dtzi, out tzi);
SYSTEMTIME localSysTime = new SYSTEMTIME();
SystemTimeToTzSpecificLocalTime(ref tzi, ref utcSysTime, out localSysTime);
// Convert SYSTEMTIME to DateTime
return(new DateTime(localSysTime.wYear, localSysTime.wMonth, localSysTime.wDay,
localSysTime.wHour, localSysTime.wMinute,
localSysTime.wSecond, localSysTime.wMilliseconds));
}
private TimeZoneInfoEx(DYNAMIC_TIME_ZONE_INFORMATION source)
{
_source = source;
Name = source.TimeZoneKeyName;
StandardName = source.StandardName;
DaylightName = source.DaylightName;
BaseUtcOffset = new TimeSpan(0, -(source.Bias + source.StandardBias), 0);
}
private TimeZoneInfoEx(DYNAMIC_TIME_ZONE_INFORMATION source)
{
_source = source;
Name = source.TimeZoneKeyName;
StandardName = source.StandardName;
DaylightName = source.DaylightName;
BaseUtcOffset = new TimeSpan(0, -(source.Bias + source.StandardBias), 0);
}
internal static AdjustmentRule CreateAdjustmentRuleFromTimeZoneInformation(ref DYNAMIC_TIME_ZONE_INFORMATION timeZoneInformation, DateTime startDate, DateTime endDate, int defaultBaseUtcOffset)
{
bool supportsDst = (timeZoneInformation.TZI.StandardDate.wMonth != 0);
if (!supportsDst)
{
if (timeZoneInformation.TZI.Bias == defaultBaseUtcOffset)
{
// this rule will not contain any information to be used to adjust dates. just ignore it
return(null);
}
return(AdjustmentRule.CreateAdjustmentRule(
startDate,
endDate,
TimeSpan.Zero, // no daylight saving transition
TransitionTime.CreateFixedDateRule(DateTime.MinValue, 1, 1),
TransitionTime.CreateFixedDateRule(DateTime.MinValue.AddMilliseconds(1), 1, 1),
new TimeSpan(0, defaultBaseUtcOffset - timeZoneInformation.TZI.Bias, 0))); // Bias delta is all what we need from this rule
}
//
// Create an AdjustmentRule with TransitionTime objects
//
TransitionTime daylightTransitionStart;
if (!TransitionTimeFromTimeZoneInformation(timeZoneInformation, out daylightTransitionStart, true /* start date */))
{
return(null);
}
TransitionTime daylightTransitionEnd;
if (!TransitionTimeFromTimeZoneInformation(timeZoneInformation, out daylightTransitionEnd, false /* end date */))
{
return(null);
}
if (daylightTransitionStart.Equals(daylightTransitionEnd))
{
// this happens when the time zone does support DST but the OS has DST disabled
return(null);
}
return(AdjustmentRule.CreateAdjustmentRule(
startDate,
endDate,
new TimeSpan(0, -timeZoneInformation.TZI.DaylightBias, 0),
(TransitionTime)daylightTransitionStart,
(TransitionTime)daylightTransitionEnd,
new TimeSpan(0, defaultBaseUtcOffset - timeZoneInformation.TZI.Bias, 0)));
}
public static extern Win32Error EnumDynamicTimeZoneInformation(uint dwIndex, out DYNAMIC_TIME_ZONE_INFORMATION lpTimeZoneInformation);
public static extern int GetDynamicTimeZoneInformation(out DYNAMIC_TIME_ZONE_INFORMATION pTimeZoneInformation);
public static extern bool TzSpecificLocalTimeToSystemTimeEx([In] ref DYNAMIC_TIME_ZONE_INFORMATION lpTimeZoneInformation, [In] ref SYSTEMTIME lpLocalTime, out SYSTEMTIME lpUniversalTime);
internal static extern bool GetTimeZoneInformationForYear([In] short wYear,
[In] ref DYNAMIC_TIME_ZONE_INFORMATION pdtzi,
out TIME_ZONE_INFORMATION ptzi);
internal static TimeZoneInfo TryCreateTimeZone(DYNAMIC_TIME_ZONE_INFORMATION timeZoneInformation)
{
uint firstYear = 0, lastYear = 0;
AdjustmentRule rule;
AdjustmentRule[] zoneRules = null;
int defaultBaseUtcOffset = timeZoneInformation.TZI.Bias;
if (String.IsNullOrEmpty(timeZoneInformation.TimeZoneKeyName))
{
return(null);
}
//
// First get the adjustment rules
//
try {
if (GetDynamicTimeZoneInformationEffectiveYears(ref timeZoneInformation, out firstYear, out lastYear) != 0)
{
firstYear = lastYear = 0;
}
} catch {
// If we don't have GetDynamicTimeZoneInformationEffectiveYears()
firstYear = lastYear = 0;
}
if (firstYear == lastYear)
{
rule = CreateAdjustmentRuleFromTimeZoneInformation(ref timeZoneInformation, DateTime.MinValue.Date, DateTime.MaxValue.Date, defaultBaseUtcOffset);
if (rule != null)
{
zoneRules = new AdjustmentRule [1] {
rule
}
}
;
}
else
{
DYNAMIC_TIME_ZONE_INFORMATION dtzi = default(DYNAMIC_TIME_ZONE_INFORMATION);
List <AdjustmentRule> rules = new List <AdjustmentRule> ();
//
// First rule
//
if (!GetTimeZoneInformationForYear((ushort)firstYear, ref timeZoneInformation, out dtzi.TZI))
{
return(null);
}
rule = CreateAdjustmentRuleFromTimeZoneInformation(ref dtzi, DateTime.MinValue.Date, new DateTime((int)firstYear, 12, 31), defaultBaseUtcOffset);
if (rule != null)
{
rules.Add(rule);
}
for (uint i = firstYear + 1; i < lastYear; i++)
{
if (!GetTimeZoneInformationForYear((ushort)i, ref timeZoneInformation, out dtzi.TZI))
{
return(null);
}
rule = CreateAdjustmentRuleFromTimeZoneInformation(ref dtzi, new DateTime((int)i, 1, 1), new DateTime((int)i, 12, 31), defaultBaseUtcOffset);
if (rule != null)
{
rules.Add(rule);
}
}
//
// Last rule
//
if (!GetTimeZoneInformationForYear((ushort)lastYear, ref timeZoneInformation, out dtzi.TZI))
{
return(null);
}
rule = CreateAdjustmentRuleFromTimeZoneInformation(ref dtzi, new DateTime((int)lastYear, 1, 1), DateTime.MaxValue.Date, defaultBaseUtcOffset);
if (rule != null)
{
rules.Add(rule);
}
if (rules.Count > 0)
{
zoneRules = rules.ToArray();
}
}
return(new TimeZoneInfo(
timeZoneInformation.TimeZoneKeyName,
new TimeSpan(0, -(timeZoneInformation.TZI.Bias), 0),
timeZoneInformation.TZI.StandardName, // we use the display name as the standared names
timeZoneInformation.TZI.StandardName,
timeZoneInformation.TZI.DaylightName,
zoneRules,
false));
}
static extern byte GetTimeZoneInformationForYear(ushort year,
ref DYNAMIC_TIME_ZONE_INFORMATION dtzi,
out TIME_ZONE_INFORMATION tzi);
internal static extern int EnumDynamicTimeZoneInformation([In] int dwIndex, out DYNAMIC_TIME_ZONE_INFORMATION lpTimeZoneInformation);
internal extern static bool GetTimeZoneInformationForYear(ushort wYear, ref DYNAMIC_TIME_ZONE_INFORMATION pdtzi, out TIME_ZONE_INFORMATION ptzi);
internal extern static uint GetDynamicTimeZoneInformationEffectiveYears(ref DYNAMIC_TIME_ZONE_INFORMATION lpTimeZoneInformation, out uint FirstYear, out uint LastYear);
internal extern static uint GetDynamicTimeZoneInformation(out DYNAMIC_TIME_ZONE_INFORMATION pTimeZoneInformation);
public static extern bool SetDynamicTimeZoneInformation([In] ref DYNAMIC_TIME_ZONE_INFORMATION lpTimeZoneInformation);
public static extern bool GetTimeZoneInformationForYear([In] ushort wYear, [In] ref DYNAMIC_TIME_ZONE_INFORMATION pdtzi, ref TIME_ZONE_INFORMATION ptzi);
internal static extern int GetDynamicTimeZoneInformation(out DYNAMIC_TIME_ZONE_INFORMATION pTimeZoneInformation);
static extern uint EnumDynamicTimeZoneInformation(uint index,
ref DYNAMIC_TIME_ZONE_INFORMATION dynamicTzi);
internal static extern int EnumDynamicTimeZoneInformation([In] int dwIndex, out DYNAMIC_TIME_ZONE_INFORMATION lpTimeZoneInformation);
public TimeZoneManager()
{
uint index = 0;
DYNAMIC_TIME_ZONE_INFORMATION tzi = new DYNAMIC_TIME_ZONE_INFORMATION();
List <TimeZoneDisplayInfo> displayInformation = new List <TimeZoneDisplayInfo>();
// Enumerate through time zones
while (0 == EnumDynamicTimeZoneInformation(index, ref tzi))
{
dynamicTzis.Add(tzi.TimeZoneKeyName, tzi);
// Create TimeZoneDisplayInfo for public property
TimeZoneDisplayInfo displayInfo = new TimeZoneDisplayInfo
{
Bias = tzi.Bias,
TimeZoneKey = tzi.TimeZoneKeyName
};
// Look up the display string
if (displayStrings.ContainsKey(tzi.TimeZoneKeyName))
{
displayInfo.Display = displayStrings[tzi.TimeZoneKeyName];
}
else if (displayStrings.ContainsKey(tzi.StandardName))
{
displayInfo.Display = displayStrings[tzi.StandardName];
}
// Or calculate one
else
{
if (tzi.Bias == 0)
{
displayInfo.Display = "(UTC) ";
}
else
{
displayInfo.Display = String.Format("(UTC{0}{1:D2}:{2:D2}) ",
tzi.Bias > 0 ? '-' : '+',
Math.Abs(tzi.Bias) / 60,
Math.Abs(tzi.Bias) % 60);
}
displayInfo.Display += tzi.TimeZoneKeyName;
}
// Add to collection
displayInformation.Add(displayInfo);
// Prepare for next iteration
index += 1;
tzi = new DYNAMIC_TIME_ZONE_INFORMATION();
}
// Sort the display information items
displayInformation.Sort((TimeZoneDisplayInfo info1, TimeZoneDisplayInfo info2) =>
{
return(info2.Bias.CompareTo(info1.Bias));
});
// Set to the publicly available property
this.DisplayInformation = displayInformation;
}
//
// TransitionTimeFromTimeZoneInformation -
//
// Converts a TimeZoneInformation (REG_TZI_FORMAT struct) to a TransitionTime
//
// * when the argument 'readStart' is true the corresponding daylightTransitionTimeStart field is read
// * when the argument 'readStart' is false the corresponding dayightTransitionTimeEnd field is read
//
private static bool TransitionTimeFromTimeZoneInformation(DYNAMIC_TIME_ZONE_INFORMATION timeZoneInformation, out TransitionTime transitionTime, bool readStartDate)
{
//
// SYSTEMTIME -
//
// If the time zone does not support daylight saving time or if the caller needs
// to disable daylight saving time, the wMonth member in the SYSTEMTIME structure
// must be zero. If this date is specified, the DaylightDate value in the
// TIME_ZONE_INFORMATION structure must also be specified. Otherwise, the system
// assumes the time zone data is invalid and no changes will be applied.
//
bool supportsDst = (timeZoneInformation.TZI.StandardDate.wMonth != 0);
if (!supportsDst)
{
transitionTime = default(TransitionTime);
return(false);
}
//
// SYSTEMTIME -
//
// * FixedDateRule -
// If the Year member is not zero, the transition date is absolute; it will only occur one time
//
// * FloatingDateRule -
// To select the correct day in the month, set the Year member to zero, the Hour and Minute
// members to the transition time, the DayOfWeek member to the appropriate weekday, and the
// Day member to indicate the occurence of the day of the week within the month (first through fifth).
//
// Using this notation, specify the 2:00a.m. on the first Sunday in April as follows:
// Hour = 2,
// Month = 4,
// DayOfWeek = 0,
// Day = 1.
//
// Specify 2:00a.m. on the last Thursday in October as follows:
// Hour = 2,
// Month = 10,
// DayOfWeek = 4,
// Day = 5.
//
if (readStartDate)
{
//
// read the "daylightTransitionStart"
//
if (timeZoneInformation.TZI.DaylightDate.wYear == 0)
{
transitionTime = TransitionTime.CreateFloatingDateRule(
new DateTime(1, /* year */
1, /* month */
1, /* day */
timeZoneInformation.TZI.DaylightDate.wHour,
timeZoneInformation.TZI.DaylightDate.wMinute,
timeZoneInformation.TZI.DaylightDate.wSecond,
timeZoneInformation.TZI.DaylightDate.wMilliseconds),
timeZoneInformation.TZI.DaylightDate.wMonth,
timeZoneInformation.TZI.DaylightDate.wDay, /* Week 1-5 */
(DayOfWeek)timeZoneInformation.TZI.DaylightDate.wDayOfWeek);
}
else
{
transitionTime = TransitionTime.CreateFixedDateRule(
new DateTime(1, /* year */
1, /* month */
1, /* day */
timeZoneInformation.TZI.DaylightDate.wHour,
timeZoneInformation.TZI.DaylightDate.wMinute,
timeZoneInformation.TZI.DaylightDate.wSecond,
timeZoneInformation.TZI.DaylightDate.wMilliseconds),
timeZoneInformation.TZI.DaylightDate.wMonth,
timeZoneInformation.TZI.DaylightDate.wDay);
}
}
else
{
//
// read the "daylightTransitionEnd"
//
if (timeZoneInformation.TZI.StandardDate.wYear == 0)
{
transitionTime = TransitionTime.CreateFloatingDateRule(
new DateTime(1, /* year */
1, /* month */
1, /* day */
timeZoneInformation.TZI.StandardDate.wHour,
timeZoneInformation.TZI.StandardDate.wMinute,
timeZoneInformation.TZI.StandardDate.wSecond,
timeZoneInformation.TZI.StandardDate.wMilliseconds),
timeZoneInformation.TZI.StandardDate.wMonth,
timeZoneInformation.TZI.StandardDate.wDay, /* Week 1-5 */
(DayOfWeek)timeZoneInformation.TZI.StandardDate.wDayOfWeek);
}
else
{
transitionTime = TransitionTime.CreateFixedDateRule(
new DateTime(1, /* year */
1, /* month */
1, /* day */
timeZoneInformation.TZI.StandardDate.wHour,
timeZoneInformation.TZI.StandardDate.wMinute,
timeZoneInformation.TZI.StandardDate.wSecond,
timeZoneInformation.TZI.StandardDate.wMilliseconds),
timeZoneInformation.TZI.StandardDate.wMonth,
timeZoneInformation.TZI.StandardDate.wDay);
}
}
return(true);
}
