Code:
/ Dotnetfx_Vista_SP2 / Dotnetfx_Vista_SP2 / 8.0.50727.4016 / DEVDIV / depot / DevDiv / releases / whidbey / NetFxQFE / ndp / clr / src / BCL / System / TimeZone.cs / 1 / TimeZone.cs
// ==++==
//
// Copyright (c) Microsoft Corporation. All rights reserved.
//
// ==--==
/*============================================================
**
** Class: TimeZone
**
**
** Purpose:
** This class is used to represent a TimeZone. It
** has methods for converting a DateTime to UTC from local time
** and to local time from UTC and methods for getting the
** standard name and daylight name of the time zone.
**
** The only TimeZone that we support in version 1 is the
** CurrentTimeZone as determined by the system timezone.
**
**
============================================================*/
namespace System {
using System;
using System.Text;
using System.Threading;
using System.Collections;
using System.Globalization;
[Serializable]
[System.Runtime.InteropServices.ComVisible(true)]
public abstract class TimeZone {
private static TimeZone currentTimeZone = null;
// Private object for locking instead of locking on a public type for SQL reliability work.
private static Object s_InternalSyncObject;
private static Object InternalSyncObject {
get {
if (s_InternalSyncObject == null) {
Object o = new Object();
Interlocked.CompareExchange(ref s_InternalSyncObject, o, null);
}
return s_InternalSyncObject;
}
}
protected TimeZone() {
}
public static TimeZone CurrentTimeZone {
get {
//Grabbing the cached value is required at the top of this function so that
//we don't incur a race condition with the ResetTimeZone method below.
TimeZone tz = currentTimeZone;
if (tz == null) {
lock(InternalSyncObject) {
if (currentTimeZone == null) {
currentTimeZone = new CurrentSystemTimeZone();
}
tz = currentTimeZone;
}
}
return (tz);
}
}
//This method is called by CultureInfo.ClearCachedData in response to control panel
//change events. It must be synchronized because otherwise there is a race condition
//with the CurrentTimeZone property above.
internal static void ResetTimeZone() {
if (currentTimeZone!=null) {
lock(InternalSyncObject) {
currentTimeZone = null;
}
}
}
public abstract String StandardName {
get;
}
public abstract String DaylightName {
get;
}
public abstract TimeSpan GetUtcOffset(DateTime time);
//
// Converts the specified datatime to the Universal time base on the current timezone
//
public virtual DateTime ToUniversalTime(DateTime time) {
if (time.Kind == DateTimeKind.Utc) {
return time;
}
long tickCount = time.Ticks - GetUtcOffset(time).Ticks;
if (tickCount>DateTime.MaxTicks) {
return new DateTime(DateTime.MaxTicks, DateTimeKind.Utc);
}
if (tickCount 03:00) 10:00 -8:00 [This time doesn't actually exist, but it can be created from DateTime]
// 03:00 10:00 -7:00
// 04:00 11:00 -7:00
// 05:00 12:00 -7:00
//
// So from 02:00 - 02:59:59, we should return the standard offset, instead of the daylight saving offset.
//
// In the transition from daylight saving time to standard time,
// if we convert local time to Universal time, we can have the
// following (take PST as an example):
// Local Universal UTC Offset
// ----- --------- ----------
// 01:00AM 08:00 -7:00
// 02:00 (=> 01:00) 09:00 -8:00
// 02:00 10:00 -8:00
// 03:00 11:00 -8:00
// 04:00 12:00 -8:00
//
// So in this case, the 02:00 does exist after the first 2:00 rolls back to 01:00. We don't need to special case this.
// But note that there are two 01:00 in the local time.
//
// And imagine if the daylight saving offset is negative (although this does not exist in real life)
// In the transition from standard time to daylight saving time,
// if we convert local time to Universal time, we can have the
// following (take PST as an example, but the daylight saving offset is -01:00):
// Local Universal UTC Offset
// ----- --------- ----------
// 01:00AM 09:00 -8:00
// 02:00 (=> 01:00) 10:00 -9:00
// 02:00 11:00 -9:00
// 03:00 12:00 -9:00
// 04:00 13:00 -9:00
// 05:00 14:00 -9:00
//
// So in this case, the 02:00 does exist after the first 2:00 rolls back to 01:00. We don't need to special case this.
//
// In the transition from daylight saving time to standard time,
// if we convert local time to Universal time, we can have the
// following (take PST as an example, daylight saving offset is -01:00):
//
// Local Universal UTC Offset
// ----- --------- ----------
// 01:00AM 10:00 -9:00
// 02:00 (=> 03:00) 11:00 -9:00
// 03:00 11:00 -8:00
// 04:00 12:00 -8:00
// 05:00 13:00 -8:00
// 06:00 14:00 -8:00
//
// So from 02:00 - 02:59:59, we should return the daylight saving offset, instead of the standard offset.
//
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;
}
}
}
// File provided for Reference Use Only by Microsoft Corporation (c) 2007.
// ==++==
//
// Copyright (c) Microsoft Corporation. All rights reserved.
//
// ==--==
/*============================================================
**
** Class: TimeZone
**
**
** Purpose:
** This class is used to represent a TimeZone. It
** has methods for converting a DateTime to UTC from local time
** and to local time from UTC and methods for getting the
** standard name and daylight name of the time zone.
**
** The only TimeZone that we support in version 1 is the
** CurrentTimeZone as determined by the system timezone.
**
**
============================================================*/
namespace System {
using System;
using System.Text;
using System.Threading;
using System.Collections;
using System.Globalization;
[Serializable]
[System.Runtime.InteropServices.ComVisible(true)]
public abstract class TimeZone {
private static TimeZone currentTimeZone = null;
// Private object for locking instead of locking on a public type for SQL reliability work.
private static Object s_InternalSyncObject;
private static Object InternalSyncObject {
get {
if (s_InternalSyncObject == null) {
Object o = new Object();
Interlocked.CompareExchange(ref s_InternalSyncObject, o, null);
}
return s_InternalSyncObject;
}
}
protected TimeZone() {
}
public static TimeZone CurrentTimeZone {
get {
//Grabbing the cached value is required at the top of this function so that
//we don't incur a race condition with the ResetTimeZone method below.
TimeZone tz = currentTimeZone;
if (tz == null) {
lock(InternalSyncObject) {
if (currentTimeZone == null) {
currentTimeZone = new CurrentSystemTimeZone();
}
tz = currentTimeZone;
}
}
return (tz);
}
}
//This method is called by CultureInfo.ClearCachedData in response to control panel
//change events. It must be synchronized because otherwise there is a race condition
//with the CurrentTimeZone property above.
internal static void ResetTimeZone() {
if (currentTimeZone!=null) {
lock(InternalSyncObject) {
currentTimeZone = null;
}
}
}
public abstract String StandardName {
get;
}
public abstract String DaylightName {
get;
}
public abstract TimeSpan GetUtcOffset(DateTime time);
//
// Converts the specified datatime to the Universal time base on the current timezone
//
public virtual DateTime ToUniversalTime(DateTime time) {
if (time.Kind == DateTimeKind.Utc) {
return time;
}
long tickCount = time.Ticks - GetUtcOffset(time).Ticks;
if (tickCount>DateTime.MaxTicks) {
return new DateTime(DateTime.MaxTicks, DateTimeKind.Utc);
}
if (tickCount 03:00) 10:00 -8:00 [This time doesn't actually exist, but it can be created from DateTime]
// 03:00 10:00 -7:00
// 04:00 11:00 -7:00
// 05:00 12:00 -7:00
//
// So from 02:00 - 02:59:59, we should return the standard offset, instead of the daylight saving offset.
//
// In the transition from daylight saving time to standard time,
// if we convert local time to Universal time, we can have the
// following (take PST as an example):
// Local Universal UTC Offset
// ----- --------- ----------
// 01:00AM 08:00 -7:00
// 02:00 (=> 01:00) 09:00 -8:00
// 02:00 10:00 -8:00
// 03:00 11:00 -8:00
// 04:00 12:00 -8:00
//
// So in this case, the 02:00 does exist after the first 2:00 rolls back to 01:00. We don't need to special case this.
// But note that there are two 01:00 in the local time.
//
// And imagine if the daylight saving offset is negative (although this does not exist in real life)
// In the transition from standard time to daylight saving time,
// if we convert local time to Universal time, we can have the
// following (take PST as an example, but the daylight saving offset is -01:00):
// Local Universal UTC Offset
// ----- --------- ----------
// 01:00AM 09:00 -8:00
// 02:00 (=> 01:00) 10:00 -9:00
// 02:00 11:00 -9:00
// 03:00 12:00 -9:00
// 04:00 13:00 -9:00
// 05:00 14:00 -9:00
//
// So in this case, the 02:00 does exist after the first 2:00 rolls back to 01:00. We don't need to special case this.
//
// In the transition from daylight saving time to standard time,
// if we convert local time to Universal time, we can have the
// following (take PST as an example, daylight saving offset is -01:00):
//
// Local Universal UTC Offset
// ----- --------- ----------
// 01:00AM 10:00 -9:00
// 02:00 (=> 03:00) 11:00 -9:00
// 03:00 11:00 -8:00
// 04:00 12:00 -8:00
// 05:00 13:00 -8:00
// 06:00 14:00 -8:00
//
// So from 02:00 - 02:59:59, we should return the daylight saving offset, instead of the standard offset.
//
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;
}
}
}
// File provided for Reference Use Only by Microsoft Corporation (c) 2007.
Link Menu
This book is available now!
Buy at Amazon US or
Buy at Amazon UK
- PathFigure.cs
- NavigateUrlConverter.cs
- Add.cs
- BlobPersonalizationState.cs
- CustomGrammar.cs
- FilterEventArgs.cs
- ClientSideProviderDescription.cs
- LogicalMethodInfo.cs
- PartialTrustVisibleAssembliesSection.cs
- IndependentlyAnimatedPropertyMetadata.cs
- Message.cs
- StateMachineAction.cs
- RemoteWebConfigurationHostStream.cs
- XPathDocumentIterator.cs
- NeutralResourcesLanguageAttribute.cs
- ClientBuildManagerCallback.cs
- Geometry.cs
- SqlProviderManifest.cs
- DateTimeOffset.cs
- SafeNativeMethods.cs
- ProxyAttribute.cs
- MetadataUtilsSmi.cs
- EpmTargetPathSegment.cs
- TrackingStringDictionary.cs
- webeventbuffer.cs
- RSAPKCS1SignatureFormatter.cs
- SystemIPGlobalProperties.cs
- UserPreferenceChangingEventArgs.cs
- _UncName.cs
- ServiceDescriptions.cs
- ClientConfigurationHost.cs
- ReflectionHelper.cs
- SHA384Managed.cs
- PrimitiveSchema.cs
- TreeWalker.cs
- ReadOnlyObservableCollection.cs
- TemplateControlParser.cs
- CodeTypeParameterCollection.cs
- SupportingTokenProviderSpecification.cs
- EmptyCollection.cs
- BinaryConverter.cs
- MetaTable.cs
- translator.cs
- PropertyEmitter.cs
- CodeRegionDirective.cs
- ClientTargetSection.cs
- MapPathBasedVirtualPathProvider.cs
- SecurityUtils.cs
- HttpPostProtocolReflector.cs
- OverflowException.cs
- AdapterUtil.cs
- DataSourceControl.cs
- HandledEventArgs.cs
- ThreadLocal.cs
- ToolStripPanelRow.cs
- FontFamily.cs
- TextBlockAutomationPeer.cs
- ExpressionEditor.cs
- nulltextnavigator.cs
- SafePEFileHandle.cs
- SqlNotificationRequest.cs
- ToolStrip.cs
- TableParaClient.cs
- ChannelCacheSettings.cs
- StorageRoot.cs
- MULTI_QI.cs
- LateBoundBitmapDecoder.cs
- ConnectionStringSettings.cs
- Parameter.cs
- TextReader.cs
- OdbcUtils.cs
- ForEachAction.cs
- CodeAttachEventStatement.cs
- DataGridViewImageColumn.cs
- Collection.cs
- ValidationError.cs
- TypeSemantics.cs
- DropAnimation.xaml.cs
- ColumnReorderedEventArgs.cs
- PeerEndPoint.cs
- PingOptions.cs
- ClaimTypes.cs
- WebContext.cs
- OperationCanceledException.cs
- SQLDateTime.cs
- BinaryFormatterWriter.cs
- ServiceOperation.cs
- DocumentStatusResources.cs
- StylusPlugin.cs
- WriterOutput.cs
- TraceContextEventArgs.cs
- MaskedTextBoxTextEditorDropDown.cs
- ObjectCacheSettings.cs
- DrawingAttributes.cs
- WindowsListViewGroup.cs
- Source.cs
- ValueQuery.cs
- ColumnHeaderCollectionEditor.cs
- DataBindingHandlerAttribute.cs
- ControlIdConverter.cs