Qt for Python (PySide/Shiboken)

Doing any sort of drawing where you want to be able to keep track of the drawing elements, zoom in on them, etc. The main one that Qt uses it for is Qt Charts. Qt Charts is implemented using the graphics view framework. These days if it was reimplemented from scratch, it probably would be implemented using QML. Qt Charts draws points and lines using QGraphicsItem primitives, and provides the user a means for zooming in and out, changing the style of points, etc.. This is all done by manipulating QGraphicsItems in a QGraphicsScene. You provide a view onto the scene by putting a QGraphicsView into your Qt Widgets app.