tokens: Just figured it out , QGraphicsView::viewportTransform() doc says " Returns a matrix that maps viewport coordinates to scene coordinates " , but in fact it returns the scene to viewport transform .
ner_tags: O O O O O B-Function O O O O O B-Data_Structure O O B-User_Interface_Element O O O O O O O O O O O O O O B-User_Interface_Element O O