What kind of object is Planning?
A widget, or a picture/pixmap/image?

If it is a widget, is paintNodes being called from withint the paintEvent ?
If not: check out this warning:

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.