QPainter immediate drawing outside paint event

Is there anyway to draw on a widget outside a painter event? QPainter seems usable only in response to paint event.

In Windows programming, one can simply obtain the client DC of a window and draw whatever you want immediately. MFC has a CClientDC class. This kind of immediate drawing is useful in some cases where custom drawing is needed during a drag & drop operation.

Thanks for sharing any ideas.

I think, this might help,

http://doc.qt.nokia.com/latest/qwidget.html#render