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QEventLoop Class Reference
[Модуль QtCore]

The QEventLoop class provides a means of entering and leaving an event loop. Далее...

 #include <QEventLoop>

Унаследован от QObject.

• Список всех членов, включая унаследованные

Открытые типы

Открытые функции

• 29 открытых функций, унаследованных от QObject

Открытые слоты

• 1 открытый слот, унаследованный от QObject

Дополнительные унаследованные члены

• 1 свойство, унаследованное от QObject
• 1 сигнал, унаследованный от QObject
• 5 статических открытых членов, унаследованных от QObject
• 7 защищенных функций, унаследованных от QObject

Подробное описание

The QEventLoop class provides a means of entering and leaving an event loop.

At any time, you can create a QEventLoop object and call exec() on it to start a local event loop. From within the event loop, calling exit() will force exec() to return.

See also QAbstractEventDispatcher.

Описание типов-членов

enum QEventLoop::ProcessEventsFlag
flags QEventLoop::ProcessEventsFlags

This enum controls the types of events processed by the processEvents() functions.

The ProcessEventsFlags type is a typedef for QFlags<ProcessEventsFlag>. It stores an OR combination of ProcessEventsFlag values.

See also processEvents().

Описание функций-членов

QEventLoop::QEventLoop ( QObject * parent = 0 )

Constructs an event loop object with the given parent.

QEventLoop::~QEventLoop ()

Destroys the event loop object.

int QEventLoop::exec ( ProcessEventsFlags flags = AllEvents )

Enters the main event loop and waits until exit() is called. Returns the value that was passed to exit().

If flags are specified, only events of the types allowed by the flags will be processed.

Эту функцию необходимо вызвать, чтобы начать обработку событий. Главный цикл обработки событий принимает события от оконной системы и отправляет их виджетам приложения.

Вообще говоря, не может происходить никакого взаимодействия с пользователем до вызова exec(). As a special case, modal widgets like QMessageBox can be used before calling exec(), because modal widgets use their own local event loop.

To make your application perform idle processing (i.e. executing a special function whenever there are no pending events), use a QTimer with 0 timeout. More sophisticated idle processing schemes can be achieved using processEvents().

See also QApplication::quit(), exit(), and processEvents().

void QEventLoop::exit ( int returnCode = 0 )

Tells the event loop to exit with a return code.

After this function has been called, the event loop returns from the call to exec(). The exec() function returns returnCode.

By convention, a returnCode of 0 means success, and any non-zero value indicates an error.

Обратите внимание, что в отличие от библиотечной функции C с тем же именем, эта функция действительно возвращается в место вызова - она останавливает обработку событий.

See also QCoreApplication::quit(), quit(), and exec().

bool QEventLoop::isRunning () const

Returns true if the event loop is running; otherwise returns false. The event loop is considered running from the time when exec() is called until exit() is called.

See also exec() and exit().

bool QEventLoop::processEvents ( ProcessEventsFlags flags = AllEvents )

Processes pending events that match flags until there are no more events to process. Returns true if pending events were handled; otherwise returns false.

This function is especially useful if you have a long running operation and want to show its progress without allowing user input; i.e. by using the ExcludeUserInputEvents flag.

This function is simply a wrapper for QAbstractEventDispatcher::processEvents(). See the documentation for that function for details.

void QEventLoop::processEvents ( ProcessEventsFlags flags, int maxTime )

Process pending events that match flags for a maximum of maxTime milliseconds, or until there are no more events to process, whichever is shorter. This function is especially useful if you have a long running operation and want to show its progress without allowing user input, i.e. by using the ExcludeUserInputEvents flag.

Примечания:

• This function does not process events continuously; it returns after all available events are processed.
• Specifying the WaitForMoreEvents flag makes no sense and will be ignored.

void QEventLoop::quit ()   [slot]

Tells the event loop to exit normally.

Same as exit(0).

See also QCoreApplication::quit() and exit().

void QEventLoop::wakeUp ()

Wakes up the event loop.

See also QAbstractEventDispatcher::wakeUp().