问如何使用鼠标在pyqt中拖动来调整QGraphicsView上的QRubberBand的大小？

EN

class MyView(QtGui.QGraphicsView):
rectChanged = pyqtSignal(QtCore.QRect)

def __init__(self):

    QtGui.QGraphicsView.__init__(self)
    self.scene = QtGui.QGraphicsScene(self)
    self.resize(1326, 400) 
    self.setScene(self.scene)
    self._pixmapHandle = None
    self.x1=0
    self.y1=0
    self.x2=0
    self.y2=0
    self.rubberBand = QtGui.QRubberBand(QtGui.QRubberBand.Rectangle, self)
    self.setMouseTracking(True)
    self.origin = QtCore.QPoint()
    self.changeRubberBand = False


    # Image aspect ratio mode.
    # !!! ONLY applies to full image. Aspect ratio is always ignored when zooming.
    #   Qt.IgnoreAspectRatio: Scale image to fit viewport.
    #   Qt.KeepAspectRatio: Scale image to fit inside viewport, preserving aspect ratio.
    #   Qt.KeepAspectRatioByExpanding: Scale image to fill the viewport, preserving aspect ratio.
    self.aspectRatioMode = Qt.KeepAspectRatio

    # Scroll bar behaviour.
    #   Qt.ScrollBarAlwaysOff: Never shows a scroll bar.
    #   Qt.ScrollBarAlwaysOn: Always shows a scroll bar.
    #   Qt.ScrollBarAsNeeded: Shows a scroll bar only when zoomed.
    self.setHorizontalScrollBarPolicy(Qt.ScrollBarAlwaysOff)
    self.setVerticalScrollBarPolicy(Qt.ScrollBarAlwaysOff)

    # Stack of QRectF zoom boxes in scene coordinates.
    self.zoomStack = []

    # Flags for enabling/disabling mouse interaction.
    self.canZoom = True
    self.canPan = True

def save(Self, filename, imgarray):
    im=Image.fromarray(imgarray, 'RGB')
    im.save(filename)

def resizeEvent(self, event):
    """ Maintain current zoom on resize.
    """
    self.rubberBand.resize(self.size())

def mousePressEvent(self, event):
    """ Start mouse pan or zoom mode.
    """
    self.x1=event.x()
    self.y1=event.y()
    if event.button() == Qt.LeftButton:
        if self.canPan:
            self.setDragMode(QtGui.QGraphicsView.ScrollHandDrag)
    elif event.button() == Qt.RightButton:
        self.origin = event.pos()
        self.rubberBand.setGeometry(QtCore.QRect(self.origin, QtCore.QSize()))
        self.rectChanged.emit(self.rubberBand.geometry())
        self.rubberBand.show()
        self.changeRubberBand = True
    QtGui.QGraphicsView.mousePressEvent(self, event)

def mouseMoveEvent(self, event):
    if self.changeRubberBand:
        self.rubberBand.setGeometry(QtCore.QRect(self.origin, event.pos()).normalized())
        self.rectChanged.emit(self.rubberBand.geometry())
    QtGui.QGraphicsView.mouseMoveEvent(self, event)

def mouseReleaseEvent(self, event):
    """ Stop mouse pan or zoom mode (apply zoom if valid).
    """    
    self.x2=event.x()
    self.y2=event.y()   
    QtGui.QGraphicsView.mouseReleaseEvent(self, event)
    scenePos = self.mapToScene(event.pos())
    if event.button() == Qt.LeftButton:
        self.setDragMode(QtGui.QGraphicsView.NoDrag)
    elif event.button() == Qt.RightButton:
        self.changeRubberBand = False
        self.setDragMode(QtGui.QGraphicsView.NoDrag)