What is difference between QTimer timeout slot calling a slot through direct connection or queued connection?

Question

I'm asking in a case where there is a lot of qt events queued in event engine. Does QTimer emit timeout() signal through event and will with queuedConnection to a slot create another event?

Answer 1

The slots connected with Qt::DirectConnection will be called immediately when the QTimer::timeout signal is emitted by QTimer. If you use a queued connection, it will schedule an event to call the slot, which will be processed by the event loop. QTimer uses timerEvent to emit the timeout signal.