from PyQt5 import QtCore, QtGui, QtWidgets

class GraphicsView(QtWidgets.QGraphicsView):

    def __init__(self, *argv, **keywords):
        super(GraphicsView, self).__init__(*argv, **keywords)
        self._numScheduledScalings = 0

    def wheelEvent(self, event):
        numDegrees = event.angleDelta().y() / 8
        numSteps = numDegrees / 15
        self._numScheduledScalings += numSteps
        if self._numScheduledScalings * numSteps < 0:
            self._numScheduledScalings = numSteps
        anim = QtCore.QTimeLine(350, self)
        anim.setUpdateInterval(20)
        anim.valueChanged.connect(self.scalingTime)
        anim.finished.connect(self.animFinished)
        anim.start()

    def scalingTime(self, x):
        factor = 1.0 + float(self._numScheduledScalings) / 300.0
        self.scale(factor, factor)

    def animFinished(self):
        if self._numScheduledScalings > 0:
            self._numScheduledScalings -= 1
        else:
            self._numScheduledScalings += 1
        
    def setScrollHandDragMode(self):
        self.setDragMode(QtWidgets.QGraphicsView.ScrollHandDrag)

    def setRubberBandDragMode(self):
        self.setDragMode(QtWidgets.QGraphicsView.RubberBandDrag)

from PyQt5 import QtWidgets, QtCore, QtGui

class GraphicsView(QtWidgets.QGraphicsView):

    def __init__(self, *argv, **keywords):
        super(GraphicsView, self).__init__(*argv, **keywords)

    def mousePressEvent(self, event):
        if event.button() == QtCore.Qt.MidButton:
            self.setDragMode(QtWidgets.QGraphicsView.ScrollHandDrag)

            event = QtGui.QMouseEvent(
                QtCore.QEvent.GraphicsSceneDragMove, 
                event.pos(), 
                QtCore.Qt.MouseButton.LeftButton, 
                QtCore.Qt.MouseButton.LeftButton, 
                QtCore.Qt.KeyboardModifier.NoModifier
            )

        elif event.button() == QtCore.Qt.LeftButton:
            self.setDragMode(QtWidgets.QGraphicsView.RubberBandDrag)

        QtWidgets.QGraphicsView.mousePressEvent(self, event)
        
    def mouseReleaseEvent(self, event):
        QtWidgets.QGraphicsView.mouseReleaseEvent(self, event)
        self.setDragMode(QtWidgets.QGraphicsView.NoDrag)

from PyQt5 import QtWidgets

class GraphicsView(QtWidgets.QGraphicsView):

    def __init__(self, *argv, **keywords):
        super(GraphicsView, self).__init__(*argv, **keywords)

    def mousePressEvent(self, event):
        QtWidgets.QGraphicsView.mousePressEvent(self, event)
        print( 'view position :', event.pos() )
        print( 'scene position :', self.mapToScene(event.pos()) )

view position : PyQt5.QtCore.QPoint(180, 124)
scene position : PyQt5.QtCore.QPointF(53.0, 29.0)