The QTimeZone class converts between UTC and local time in a specific time zone. 更多...
| 头： | #include <QTimeZone> |
| qmake: | QT += core |
| Since: | Qt 5.2 |
注意： 此类的所有函数 thread-safe .
| class | OffsetData |
| enum | NameType { DefaultName, LongName, ShortName, OffsetName } |
| typedef | OffsetDataList |
| enum | TimeType { StandardTime, DaylightTime, GenericTime } |
| enum | anonymous { MinUtcOffsetSecs, MaxUtcOffsetSecs } |
| QTimeZone () | |
| QTimeZone (const QByteArray & ianaId ) | |
| QTimeZone (int offsetSeconds ) | |
| QTimeZone (const QByteArray & ianaId , int offsetSeconds , const QString & name , const QString & abbreviation , QLocale::Country country = QLocale::AnyCountry, const QString & comment = QString()) | |
| QTimeZone (const QTimeZone & other ) | |
| ~QTimeZone () | |
| QString | abbreviation (const QDateTime & atDateTime ) const |
| QString | comment () const |
| QLocale::Country | country () const |
| int | daylightTimeOffset (const QDateTime & atDateTime ) const |
| QString | displayName (const QDateTime & atDateTime , QTimeZone::NameType nameType = QTimeZone::DefaultName, const QLocale & locale = QLocale()) const |
| QString | displayName (QTimeZone::TimeType timeType , QTimeZone::NameType nameType = QTimeZone::DefaultName, const QLocale & locale = QLocale()) const |
| bool | hasDaylightTime () const |
| bool | hasTransitions () const |
| QByteArray | id () const |
| bool | isDaylightTime (const QDateTime & atDateTime ) const |
| bool | isValid () const |
| QTimeZone::OffsetData | nextTransition (const QDateTime & afterDateTime ) const |
| QTimeZone::OffsetData | offsetData (const QDateTime & forDateTime ) const |
| int | offsetFromUtc (const QDateTime & atDateTime ) const |
| QTimeZone::OffsetData | previousTransition (const QDateTime & beforeDateTime ) const |
| int | standardTimeOffset (const QDateTime & atDateTime ) const |
| void | swap (QTimeZone & other ) |
| CFTimeZoneRef | toCFTimeZone () const |
| NSTimeZone * | toNSTimeZone () const |
| QTimeZone::OffsetDataList | transitions (const QDateTime & fromDateTime , const QDateTime & toDateTime ) const |
| bool | operator!= (const QTimeZone & other ) const |
| QTimeZone & | operator= (const QTimeZone & other ) |
| QTimeZone & | operator= (QTimeZone && other ) |
| bool | operator== (const QTimeZone & other ) const |
| QList<QByteArray> | availableTimeZoneIds () |
| QList<QByteArray> | availableTimeZoneIds (QLocale::Country country ) |
| QList<QByteArray> | availableTimeZoneIds (int offsetSeconds ) |
| QTimeZone | fromCFTimeZone (CFTimeZoneRef timeZone ) |
| QTimeZone | fromNSTimeZone (const NSTimeZone * timeZone ) |
| QByteArray | ianaIdToWindowsId (const QByteArray & ianaId ) |
| bool | isTimeZoneIdAvailable (const QByteArray & ianaId ) |
| QTimeZone | systemTimeZone () |
| QByteArray | systemTimeZoneId () |
| QTimeZone | utc () |
| QByteArray | windowsIdToDefaultIanaId (const QByteArray & windowsId ) |
| QByteArray | windowsIdToDefaultIanaId (const QByteArray & windowsId , QLocale::Country country ) |
| QList<QByteArray> | windowsIdToIanaIds (const QByteArray & windowsId ) |
| QList<QByteArray> | windowsIdToIanaIds (const QByteArray & windowsId , QLocale::Country country ) |
The QTimeZone class converts between UTC and local time in a specific time zone.
This class provides a stateless calculator for time zone conversions between UTC and the local time in a specific time zone. By default it uses the host system time zone data to perform these conversions.
This class is primarily designed for use in QDateTime ; most applications will not need to access this class directly and should instead use QDateTime 采用 Qt::TimeSpec of Qt::TimeZone .
注意： For consistency with QDateTime , QTimeZone does not account for leap seconds.
QTimeZone uses the IANA time zone IDs as defined in the IANA Time Zone Database (http://www.iana.org/time-zones). This is to ensure a standard ID across all supported platforms. Most platforms support the IANA IDs and the IANA Database natively, but for Windows a mapping is required to the native IDs. See below for more details.
The IANA IDs can and do change on a regular basis, and can vary depending on how recently the host system data was updated. As such you cannot rely on any given ID existing on any host system. You must use availableTimeZoneIds () to determine what IANA IDs are available.
The IANA IDs and database are also know as the Olson IDs and database, named after their creator.
A default UTC time zone backend is provided which is always guaranteed to be available. This provides a set of generic Offset From UTC time zones in the range UTC-14:00 to UTC+14:00. These time zones can be created using either the standard ISO format names "UTC+00:00" as listed by availableTimeZoneIds (), or using the number of offset seconds.
Windows native time zone support is severely limited compared to the standard IANA TZ Database. Windows time zones cover larger geographic areas and are thus less accurate in their conversions. They also do not support as much historic conversion data and so may only be accurate for the current year.
QTimeZone uses a conversion table derived form the Unicode CLDR data to map between IANA IDs and Windows IDs. Depending on your version of Windows and Qt, this table may not be able to provide a valid conversion, in which "UTC" will be returned.
QTimeZone provides a public API to use this conversion table. The Windows ID used is the Windows Registry Key for the time zone which is also the MS Exchange EWS ID as well, but is different to the Time Zone Name (TZID) and COD code used by MS Exchange in versions before 2007.
QTimeZone does not support any concept of a system or default time zone. If you require a QDateTime that uses the current system time zone at any given moment then you should use a Qt::TimeSpec of Qt::LocalTime .
The method systemTimeZoneId () returns the current system IANA time zone ID which on Unix-like systems will always be correct. On Windows this ID is translated from the Windows system ID using an internal translation table and the user's selected country. As a consequence there is a small chance any Windows install may have IDs not known by Qt, in which case "UTC" will be returned.
Creating a new QTimeZone instance using the system time zone ID will only produce a fixed named copy of the time zone, it will not change if the system time zone changes.
The difference between UTC and the local time in a time zone is expressed as an offset in seconds from UTC, i.e. the number of seconds to add to UTC to obtain the local time. The total offset is comprised of two component parts, the standard time offset and the daylight-saving time offset. The standard time offset is the number of seconds to add to UTC to obtain standard time in the time zone. The daylight-saving time offset is the number of seconds to add to the standard time offset to obtain daylight-saving time (abbreviated DST and sometimes called "daylight time" or "summer time") in the time zone.
Note that the standard and DST offsets for a time zone may change over time as countries have changed DST laws or even their standard time offset.
This class includes data obtained from the CLDR data files under the terms of the Unicode Data Files and Software License. See Unicode Common Locale Data Repository (CLDR) for details.
另请参阅 QDateTime .
The type of time zone name.
| 常量 | 值 | 描述 |
|---|---|---|
QTimeZone::DefaultName
|
0
|
The default form of the time zone name, e.g. LongName, ShortName or OffsetName |
QTimeZone::LongName
|
1
|
The long form of the time zone name, e.g. "Central European Time" |
QTimeZone::ShortName
|
2
|
The short form of the time zone name, usually an abbreviation, e.g. "CET" |
QTimeZone::OffsetName
|
3
|
The standard ISO offset form of the time zone name, e.g. "UTC+01:00" |
同义词 QVector < OffsetData >.
The type of time zone time, for example when requesting the name. In time zones that do not apply DST, all three values may return the same result.
| 常量 | 值 | 描述 |
|---|---|---|
QTimeZone::StandardTime
|
0
|
The standard time in a time zone, i.e. when Daylight-Saving is not in effect. For example when formatting a display name this will show something like "Pacific Standard Time". |
QTimeZone::DaylightTime
|
1
|
A time when Daylight-Saving is in effect. For example when formatting a display name this will show something like "Pacific daylight-saving time". |
QTimeZone::GenericTime
|
2
|
A time which is not specifically Standard or Daylight-Saving time, either an unknown time or a neutral form. For example when formatting a display name this will show something like "Pacific Time". |
Sane UTC offsets range from -14 to +14 hours. No known zone > 12 hrs West of Greenwich (Baker Island, USA). No known zone > 14 hrs East of Greenwich (Kiritimati, Christmas Island, Kiribati).
| 常量 | 值 | 描述 |
|---|---|---|
QTimeZone::MinUtcOffsetSecs
|
-14 * 3600
|
-14 * 3600, |
QTimeZone::MaxUtcOffsetSecs
|
+14 * 3600
|
+14 * 3600 |
Create a null/invalid time zone instance.
Creates an instance of the requested time zone ianaId .
The ID must be one of the available system IDs otherwise an invalid time zone will be returned.
另请参阅 availableTimeZoneIds ().
Creates an instance of a time zone with the requested Offset from UTC of offsetSeconds .
The offsetSeconds from UTC must be in the range -14 hours to +14 hours otherwise an invalid time zone will be returned.
Creates a custom time zone with an ID of ianaId and an offset from UTC of offsetSeconds 。 name will be the name used by displayName () 为 LongName ， abbreviation will be used by displayName () 为 ShortName and by abbreviation (), and the optional country will be used by country ()。 comment is an optional note that may be displayed in a GUI to assist users in selecting a time zone.
The ianaId must not be one of the available system IDs returned by availableTimeZoneIds ()。 offsetSeconds from UTC must be in the range -14 hours to +14 hours.
If the custom time zone does not have a specific country then set it to the default value of QLocale::AnyCountry .
Copy constructor, copy other to this.
Destroys the time zone.
Returns the time zone abbreviation at the given atDateTime . The abbreviation may change depending on DST or even historical events.
Note that the abbreviation is not guaranteed to be unique to this time zone and should not be used in place of the ID or display name.
另请参阅 displayName ().
[static]
QList
<
QByteArray
> QTimeZone::
availableTimeZoneIds
()
Returns a list of all available IANA time zone IDs on this system.
另请参阅 isTimeZoneIdAvailable ().
[static]
QList
<
QByteArray
> QTimeZone::
availableTimeZoneIds
(
QLocale::Country
country
)
Returns a list of all available IANA time zone IDs for a given country .
作为特殊情况， country of Qt::AnyCountry returns those time zones that do not have any country related to them, such as UTC. If you require a list of all time zone IDs for all countries then use the standard availableTimeZoneIds () 方法。
另请参阅 isTimeZoneIdAvailable ().
[static]
QList
<
QByteArray
> QTimeZone::
availableTimeZoneIds
(
int
offsetSeconds
)
Returns a list of all available IANA time zone IDs with a given standard time offset of offsetSeconds .
另请参阅 isTimeZoneIdAvailable ().
Returns any comment for the time zone.
A comment may be provided by the host platform to assist users in choosing the correct time zone. Depending on the platform this may not be localized.
Returns the country for the time zone.
Returns the daylight-saving time offset at the given atDateTime , i.e. the number of seconds to add to the standard time offset to obtain the local daylight-saving time.
For example, for the time zone "Europe/Berlin" the DST offset is +3600 seconds. During standard time daylightTimeOffset() will return 0, and when daylight-saving is in effect it will return +3600.
另请参阅 offsetFromUtc () 和 standardTimeOffset ().
Returns the localized time zone display name at the given atDateTime 为给定 nameType 以给定 locale 。 nameType and locale requested may not be supported on all platforms, in which case the best available option will be returned.
若 locale is not provided then the application default locale will be used.
The display name may change depending on DST or historical events.
另请参阅 abbreviation ().
Returns the localized time zone display name for the given timeType and nameType 以给定 locale 。 nameType and locale requested may not be supported on all platforms, in which case the best available option will be returned.
若 locale is not provided then the application default locale will be used.
Where the time zone display names have changed over time then the most recent names will be used.
另请参阅 abbreviation ().
[static]
QTimeZone
QTimeZone::
fromCFTimeZone
(
CFTimeZoneRef
timeZone
)
构造新的 QTimeZone containing a copy of the CFTimeZone timeZone .
该函数在 Qt 5.9 引入。
另请参阅 toCFTimeZone ().
[static]
QTimeZone
QTimeZone::
fromNSTimeZone
(const
NSTimeZone
*
timeZone
)
构造新的 QTimeZone containing a copy of the NSTimeZone timeZone .
该函数在 Qt 5.9 引入。
另请参阅 toNSTimeZone ().
返回
true
if the time zone has practiced daylight-saving at any time.
另请参阅 isDaylightTime () 和 daylightTimeOffset ().
返回
true
if the system backend supports obtaining transitions.
Transitions are changes in the time-zone: these happen when DST turns on or off and when authorities alter the offsets for the time-zone.
另请参阅 nextTransition (), previousTransition ()，和 transitions ().
[static]
QByteArray
QTimeZone::
ianaIdToWindowsId
(const
QByteArray
&
ianaId
)
Returns the Windows ID equivalent to the given ianaId .
另请参阅 windowsIdToDefaultIanaId () 和 windowsIdToIanaIds ().
Returns the IANA ID for the time zone.
IANA IDs are used on all platforms. On Windows these are translated from the Windows ID into the closest IANA ID for the time zone and country.
返回
true
if daylight-saving was in effect at the given
atDateTime
.
另请参阅 hasDaylightTime () 和 daylightTimeOffset ().
[static]
bool
QTimeZone::
isTimeZoneIdAvailable
(const
QByteArray
&
ianaId
)
返回
true
if a given time zone
ianaId
is available on this system.
另请参阅 availableTimeZoneIds ().
返回
true
if this time zone is valid.
Returns the first time zone Transition after the given afterDateTime . This is most useful when you have a Transition time and wish to find the Transition after it.
If there is no transition after the given afterDateTime then an invalid OffsetData will be returned with an invalid QDateTime .
给定 afterDateTime is exclusive.
另请参阅 hasTransitions (), previousTransition ()，和 transitions ().
Returns the effective offset details at the given forDateTime . This is the equivalent of calling offsetFromUtc (), abbreviation (), etc individually but is more efficient.
另请参阅 offsetFromUtc (), standardTimeOffset (), daylightTimeOffset ()，和 abbreviation ().
Returns the total effective offset at the given atDateTime , i.e. the number of seconds to add to UTC to obtain the local time. This includes any DST offset that may be in effect, i.e. it is the sum of standardTimeOffset () 和 daylightTimeOffset () for the given datetime.
For example, for the time zone "Europe/Berlin" the standard time offset is +3600 seconds and the DST offset is +3600 seconds. During standard time offsetFromUtc() will return +3600 (UTC+01:00), and during DST it will return +7200 (UTC+02:00).
另请参阅 standardTimeOffset () 和 daylightTimeOffset ().
Returns the first time zone Transition before the given beforeDateTime . This is most useful when you have a Transition time and wish to find the Transition before it.
If there is no transition before the given beforeDateTime then an invalid OffsetData will be returned with an invalid QDateTime .
给定 beforeDateTime is exclusive.
另请参阅 hasTransitions (), nextTransition ()，和 transitions ().
Returns the standard time offset at the given atDateTime , i.e. the number of seconds to add to UTC to obtain the local Standard Time. This excludes any DST offset that may be in effect.
For example, for the time zone "Europe/Berlin" the standard time offset is +3600 seconds. During both standard and DST offsetFromUtc () will return +3600 (UTC+01:00).
另请参阅 offsetFromUtc () 和 daylightTimeOffset ().
Swaps this time zone instance with other 。此函数非常快且从不失败。
[static]
QTimeZone
QTimeZone::
systemTimeZone
()
返回 QTimeZone object that refers to the local system time, as specified by systemTimeZoneId ().
该函数在 Qt 5.5 引入。
另请参阅 utc ().
[static]
QByteArray
QTimeZone::
systemTimeZoneId
()
Returns the current system time zone IANA ID.
On Windows this ID is translated from the Windows ID using an internal translation table and the user's selected country. As a consequence there is a small chance any Windows install may have IDs not known by Qt, in which case "UTC" will be returned.
Creates a CFTimeZone from a QTimeZone . The caller owns the CFTimeZone object and is responsible for releasing it.
该函数在 Qt 5.9 引入。
另请参阅 fromCFTimeZone ().
Creates an NSTimeZone from a QTimeZone . The NSTimeZone object is autoreleased.
该函数在 Qt 5.9 引入。
另请参阅 fromNSTimeZone ().
Returns a list of all time zone transitions between the given datetimes.
给定 fromDateTime and toDateTime are inclusive.
另请参阅 hasTransitions (), nextTransition ()，和 previousTransition ().
[static]
QTimeZone
QTimeZone::
utc
()
返回 QTimeZone object that refers to UTC (Universal Time Coordinated).
该函数在 Qt 5.5 引入。
另请参阅 systemTimeZone ().
[static]
QByteArray
QTimeZone::
windowsIdToDefaultIanaId
(const
QByteArray
&
windowsId
)
Returns the default IANA ID for a given windowsId .
Because a Windows ID can cover several IANA IDs in several different countries, this function returns the most frequently used IANA ID with no regard for the country and should thus be used with care. It is usually best to request the default for a specific country.
另请参阅 ianaIdToWindowsId () 和 windowsIdToIanaIds ().
[static]
QByteArray
QTimeZone::
windowsIdToDefaultIanaId
(const
QByteArray
&
windowsId
,
QLocale::Country
country
)
Returns the default IANA ID for a given windowsId and country .
Because a Windows ID can cover several IANA IDs within a given country, the most frequently used IANA ID in that country is returned.
As a special case, QLocale::AnyCountry returns the default of those IANA IDs that do not have any specific country.
另请参阅 ianaIdToWindowsId () 和 windowsIdToIanaIds ().
[static]
QList
<
QByteArray
> QTimeZone::
windowsIdToIanaIds
(const
QByteArray
&
windowsId
)
Returns all the IANA IDs for a given windowsId .
The returned list is sorted alphabetically.
另请参阅 ianaIdToWindowsId () 和 windowsIdToDefaultIanaId ().
[static]
QList
<
QByteArray
> QTimeZone::
windowsIdToIanaIds
(const
QByteArray
&
windowsId
,
QLocale::Country
country
)
Returns all the IANA IDs for a given windowsId and country .
As a special case QLocale::AnyCountry returns those IANA IDs that do not have any specific country.
The returned list is in order of frequency of usage, i.e. larger zones within a country are listed first.
另请参阅 ianaIdToWindowsId () 和 windowsIdToDefaultIanaId ().
返回
true
if this time zone is not equal to the
other
time zone.
Assignment operator, assign other to this.
移动赋值 other 到此 QTimeZone instance, transferring the ownership of the managed pointer to this instance.
返回
true
if this time zone is equal to the
other
time zone.