diff options
author | Thiago Macieira <thiago.macieira@intel.com> | 2013-10-01 11:25:48 -0700 |
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committer | The Qt Project <gerrit-noreply@qt-project.org> | 2013-10-02 03:15:09 +0200 |
commit | c74f60b09dc031b19ebfa11718d44fb06a5569b2 (patch) | |
tree | fc93ba0e8c1f3b78d6207096161d1fe3995801b3 /src/corelib/kernel | |
parent | 649e0b6002490decfff6477d15229786e9db8f9c (diff) |
Doc: correct QTimer accuracy information - it depends on the timer type
This doc was probably older than the feature of timer types.
Task-number: QTBUG-33760
Change-Id: Iff4c9f9bb7287498f1ee80578b500bbde777bc78
Reviewed-by: Olivier Goffart <ogoffart@woboq.com>
Diffstat (limited to 'src/corelib/kernel')
-rw-r--r-- | src/corelib/kernel/qtimer.cpp | 19 |
1 files changed, 12 insertions, 7 deletions
diff --git a/src/corelib/kernel/qtimer.cpp b/src/corelib/kernel/qtimer.cpp index 667c490d31..71d8d99a91 100644 --- a/src/corelib/kernel/qtimer.cpp +++ b/src/corelib/kernel/qtimer.cpp @@ -103,18 +103,23 @@ QT_BEGIN_NAMESPACE \section1 Accuracy and Timer Resolution - Timers will never time out earlier than the specified timeout value - and they are not guaranteed to time out at the exact value specified. - In many situations, they may time out late by a period of time that - depends on the accuracy of the system timers. - The accuracy of timers depends on the underlying operating system and hardware. Most platforms support a resolution of 1 millisecond, though the accuracy of the timer will not equal this resolution in many real-world situations. - If Qt is unable to deliver the requested number of timer clicks, - it will silently discard some. + The accuracy also depends on the \l{Qt::TimerType}{timer type}. For + Qt::PreciseTimer, QTimer will try to keep the accurance at 1 millisecond. + Precise timers will also never time out earlier than expected. + + For Qt::CoarseTimer and Qt::VeryCoarseTimer types, QTimer may wake up + earlier than expected, within the margins for those types: 5% of the + interval for Qt::CoarseTimer and 500 ms for Qt::VeryCoarseTimer. + + All timer types may time out later than expected if the system is busy or + unable to provide the requested accuracy. In such a case of timeout + overrun, Qt will emit activated() only once, even if multiple timeouts have + expired, and then will resume the original interval. \section1 Alternatives to QTimer |