Drawing rectangles in QT

[wayfaerer]

Then you should reimplement some protected functions in your QGraphicsItems, particularly mousePressEvent, mouseMoveEvent, and mouseReleaseEvent. mousePressEvent would notify the item to draw a line (probably another QGraphicsItem), from the initial click location to mouseMoveEvent's current location. mouseReleaseEvent could call scene().itemAt() to determine which node is at the mouse release location. Something like that.