QPainter problem - migration from qt3 [SOLVED]

[tpomorsk]

Problem solved.
In fact paintEvent() was slow because of double-buffering, which is turned on by default in Qt4. All I had to do is to turn it off.
I used JPN's code and added the following line in the constructor of my main class (whiteboard)

this->setAttribute(Qt::WA_PaintOnScreen);

this->setAttribute(Qt::WA_PaintOnScreen);

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After that there is no difference in performance between qt4 and qt3.


Thanks for help,
Tomek

[high_flyer]

In fact paintEvent() was slow because of double-buffering, which is turned on by default in Qt4.

Thanks for pointing that out.
Another handy point to check in the future, if painting is slow.