CODEWITHSUNDEEP
user-interfaceqt
yan bellavance
yan bellavance

Reputation: 4830

Should I use QCoreApplication::processEvents() or QApplication::processEvents()?

I have a method which is called from both QThreads and the main thread. this method can sometimes take a long time to do its computations in a loop so I put QCoreApplication::processEvents() and this prevents the GUI from freezing. At some point I had changed QCoreApplication::processEvents() for QApplication::processEvents() but that caused the GUI to freeze (im pretty sure thats what was fereezing it because since I put QCoreApplication::processEvents() back it hasnt frozen again) Am I right to think that calling QApplication::processEvents() from both the main thread and QThreads can freeze the GUI?

Upvotes: 15

Views: 51013

Answers (2)

Kaleb Pederson
Kaleb Pederson

Reputation: 46479

You'll be much better off moving the long-running process out of the main thread so you don't need to call processEvents(). Within that long-running process, you can emit whatever signals you need so the gui has sufficient information to do updates, etc. processEvents, however, is usually a crutch for a poor design.

Upvotes: 12

gregseth
gregseth

Reputation: 13408

Neither, processEvent() should be calld only when you have actual pending events to process. You may find this useful : How to make Qt work when main thread is busy?

Upvotes: 12

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