QQmlIncubationController#
QQmlIncubationController
instances drive the progress of QQmlIncubators. More…
Synopsis#
Functions#
def
engine
()def
incubateFor
(msecs)def
incubateWhile
(flag[, msecs=0])def
incubatingObjectCount
()
Virtual functions#
def
incubatingObjectCountChanged
(arg__1)
Note
This documentation may contain snippets that were automatically translated from C++ to Python. We always welcome contributions to the snippet translation. If you see an issue with the translation, you can also let us know by creating a ticket on https:/bugreports.qt.io/projects/PYSIDE
Detailed Description#
In order to behave asynchronously and not introduce stutters or freezes in an application, the process of creating objects a QQmlIncubators must be driven only during the application’s idle time. QQmlIncubationController
allows the application to control exactly when, how often and for how long this processing occurs.
A QQmlIncubationController
derived instance should be created and set on a QQmlEngine
by calling the setIncubationController()
method. Processing is then controlled by calling the incubateFor()
or incubateWhile()
methods as dictated by the application’s requirements.
For example, this is an example of a incubation controller that will incubate for a maximum of 5 milliseconds out of every 16 milliseconds.
class PeriodicIncubationController : public QObject, public QQmlIncubationController { public: PeriodicIncubationController() { startTimer(16); } protected: void timerEvent(QTimerEvent *) override { incubateFor(5); } };
Although the example works, it is heavily simplified. Real world incubation controllers try and maximize the amount of idle time they consume while not disturbing the application. Using a static amount of 5 milliseconds like above may both leave idle time on the table in some frames and disturb the application in others.
QQuickWindow, QQuickView, and QQuickWidget all pre-create an incubation controller that spaces out incubation over multiple frames using a more intelligent algorithm. You rarely have to write your own.
- class PySide6.QtQml.QQmlIncubationController#
Create a new incubation controller.
- PySide6.QtQml.QQmlIncubationController.engine()#
- Return type:
Return the QQmlEngine
this incubation controller is set on, or 0 if it has not been set on any engine.
- PySide6.QtQml.QQmlIncubationController.incubateFor(msecs)#
- Parameters:
msecs – int
Incubate objects for msecs
, or until there are no more objects to incubate.
- PySide6.QtQml.QQmlIncubationController.incubateWhile(flag[, msecs=0])#
- Parameters:
flag –
atomic
msecs – int
Incubate objects while the atomic bool pointed to by flag
is true, or until there are no more objects to incubate, or up to msecs
if msecs
is not zero.
Generally this method is used in conjunction with a thread or a UNIX signal that sets the bool pointed to by flag
to false when it wants incubation to be interrupted.
Note
flag
is read using acquire memory ordering.
- PySide6.QtQml.QQmlIncubationController.incubatingObjectCount()#
- Return type:
int
Return the number of objects currently incubating.
- PySide6.QtQml.QQmlIncubationController.incubatingObjectCountChanged(arg__1)#
- Parameters:
arg__1 – int
Called when the number of incubating objects changes. incubatingObjectCount
is the new number of incubating objects.
The default implementation does nothing.