The View, QGraphicsView

We're down to the last part of The Graphics View Framework in Qt. The QGraphicsView class is a Qt Widget class that can be placed on a window to display QGraphicsScene, which itself contains a number of QGraphicsItem subclasses and/or widgets. Similar to the QGraphicsScene class, this class also provides tons of capabilities, methods, and properties to deal with the visualization part of the graphics. We'll review some of the most important ones in the following list, and then we'll learn how to subclass QGraphicsView and extend it to have several important capabilities in our comprehensive vision application, such as zoom in, zoom out, item selection, and so on. So, here are the methods and members of the QGraphicsView class that we'll need in a computer vision project:

• The alignment and setAlignment functions can be used to set the alignment of the scene in the view. It's important to note that this will only have a visible effect when the view can completely display...