[Qt-interest] Using QTimers during a QDrag

[Daniel Price]

We're using a QTimer to auto-scroll some Qt views (trees, graphics views etc) and it works fine except during a drag when on Windows, the timer stops calling it's slot at the requested frequency. It does fire off signals but at a greatly reduced rate resulting in jerky scrolling.

According to the docs, QDrag::exec blocks the Windows event loop. However, processEvents is still periodically called from within Qt to allow some events, including timers, to work.

I've tried using separate QThreads, QBasicTimer and even Win32 API TimerQueues and straight callback functions to get around the problem but they all have the same issue; the event loop is blocked.

Is there any solution to this? Short of not using QDrag and creating our own drag and drop system (not practical). It only happens on Windows.



Daniel Price
Software Engineer
FXhome Limited

daniel.price at fxhome.com<mailto:tim.edwards at fxhome.com>
http://fxhome.com


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FXhome Limited is a limited company registered in England and Wales. Registered number: 04172812. Registered office: The Henderson Business Centre, Ivy Road, Norwich, Norfolk, NR5 8BF, U.K.
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