[Interest] QProgressDialog not showing & processEvents()

Etienne Sandré-Chardonnal etienne.sandre at m4x.org
Fri Nov 15 14:05:48 CET 2013

Dear all,

I have a long file saving function (gigabytes - several minutes) and I am
trying to use QProcessDialog. I am using it the Modal way as explained in
the documentation. However, the dialog appears after about 50 seconds,
despite having set the minimumDuration to 0, and called setValue() several
times before.

Googling for the issue says I need to call QApplication::processEvents
regularly in order for the GUI to refresh. However, the doc says :

"If the progress dialog is modal
setValue() callsQApplication::processEvents<qthelp://com.trolltech.qt.481/qdoc/qcoreapplication.html#processEvents>(),
so take care that this does not cause undesirable re-entrancy in your code"

So I'm puzzled... Do I need to call it, or is it already called by
setValue? In the example there are no explicit calls to processEvents().

Qt 4.8.1


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