diff options
Diffstat (limited to 'src/corelib/kernel/qtimer.cpp')
| -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 |