QEventLoop¶
- PyQt5.QtCore.QEventLoop
Inherits from QObject.
Description¶
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
Classes¶
Enums¶
- ProcessEventsFlag
This enum controls the types of events processed by the processEvents() functions.
See also
Member
Value
Description
AllEvents 0x00
All events. Note that DeferredDelete events are processed specially. See deleteLater() for more details.
ExcludeSocketNotifiers 0x02
Do not process socket notifier events. Note that the events are not discarded; they will be delivered the next time processEvents() is called without the flag.
ExcludeUserInputEvents 0x01
Do not process user input events, such as ButtonPress and KeyPress. Note that the events are not discarded; they will be delivered the next time processEvents() is called without the flag.
WaitForMoreEvents 0x04
Wait for events if no pending events are available.
X11ExcludeTimers TODO
TODO
Methods¶
- __init__(parent: QObject = None)
Constructs an event loop object with the given parent.
- event(QEvent) → bool
TODO
- exec(flags: ProcessEventsFlags = AllEvents) → int
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.
It is necessary to call this function to start event handling. The main event loop receives events from the window system and dispatches these to the application widgets.
Generally speaking, no user interaction can take place before calling . As a special case, modal widgets like QMessageBox can be used before calling , 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
- exec_(flags: ProcessEventsFlags = AllEvents) → int
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.
It is necessary to call this function to start event handling. The main event loop receives events from the window system and dispatches these to the application widgets.
Generally speaking, no user interaction can take place before calling . As a special case, modal widgets like QMessageBox can be used before calling , 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
- exit(returnCode: int = 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.
Note that unlike the C library function of the same name, this function does return to the caller – it is event processing that stops.
- isRunning() → bool
Returns
trueif 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.
- processEvents(flags: Union[ProcessEventsFlags, ProcessEventsFlag] = AllEvents) → bool
Processes pending events that match flags until there are no more events to process. Returns
trueif pending events were handled; otherwise returnsfalse.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 processEvents(). See the documentation for that function for details.
- processEvents(Union[ProcessEventsFlags, ProcessEventsFlag], int)
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.
Notes:
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.
- quit()
Tells the event loop to exit normally.
Same as exit(0).
- wakeUp()
Wakes up the event loop.
See also
