Graphics View architecture

Three components form the core of Graphics View: an instance of QGraphicsView, which is referred to as view; an instance of QGraphicsScene, which is referred to as scene; and usually multiple instances of QGraphicsItem, which are referred to as items. The usual workflow is to first create a couple of items, then add them to a scene, and finally set that scene on a view.

In the following section, we will be discussing all three parts of the Graphics View architecture one after the other, beginning with the items, followed by the scene, and concluding with the view.

An illustration of Graphics View components

However, because it is not possible to deal with one component as entirely separate from the others, you need to get the big picture up front. This will help you to better understand the description of the three single parts. And do not worry if you do not understand all the details on their first occurrence. Be patient, work through the three parts, and all issues...