Question

I have a widget class subclass of QMainWindow, and it has a central widget(QWidget), and in the overriden paintEvent function, can I create an instance of QPainter on this central widget? Code like:

void MyMainWindow::paintEvent(QEvent *event)
{
    QPainter painter(_theCentralWidget);
    //drawing...
    return QMainWindow::paintEvent(event);
}

I don’t want to create a new c++ class subclass of QWidget and override its paintEvent function and then replace the original central widget with this new one…
(I did like above but an error occured saying the painter is not active…)

Answer 1

“Warning: When the paintdevice is a widget, QPainter can only be used inside a paintEvent() function or in a function called by paintEvent(); that is unless the Qt::WA_PaintOutsidePaintEvent widget attribute is set. On Mac OS X and Windows, you can only paint in a paintEvent() function regardless of this attribute’s setting.”

From: QT Docu