qgraphicsview wheel to zoom

QGraphicsView has built-in support for zooming using the mouse wheel. Here's how you can use it:

1. Enable mouse tracking on the view:

view.setMouseTracking(True)

2. Connect the `wheelEvent` of the view to a slot that handles the zooming:

view.wheelEvent = self.handleWheelEvent

3. In the slot, adjust the view's zoom level based on the mouse wheel delta:

def handleWheelEvent(self, event):
    delta = event.angleDelta().y()
    zoomFactor = 1.2
    if delta > 0:
        self.view.scale(zoomFactor, zoomFactor)
    else:
        self.view.scale(1 / zoomFactor, 1 / zoomFactor)

This code will zoom the view in/out by a factor of 1.2 each time the mouse wheel is scrolled up/down. You can adjust the zoom factor to suit your needs.