鼠标的绝对坐标单击图像

Question

我正在用python PyQt4构建图像编辑器。我已经声明了一个QGraphicsView类，其中包含QGraphicsScene来显示图像。我单击图像时需要图像的坐标，而不是QGraphicsView的坐标。我该如何实现。我附上我的QGraphicsView类以供参考。

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

def __init__(self):
    super(MyView, self).__init__()
    #QtGui.QGraphicsView.__init__(self)
    self.setGeometry(20, 30, 100, 200)
    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.choice=2
    self.rubberBand = QtGui.QRubberBand(QtGui.QRubberBand.Rectangle, self)
    self.setMouseTracking(True)
    self.origin = QtCore.QPoint()
    self.changeRubberBand = False
    self.rubberBand.move(0, 0)


    # 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):
    if (len(imgarray.shape))==3:
        im=Image.fromarray(imgarray, 'RGB')
    else:
        im=Image.fromarray(imgarray)
    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()
    print(self.x1)
    print(self.y1)
    if event.button() == Qt.LeftButton:
        if self.canPan:
            self.setDragMode(QtGui.QGraphicsView.ScrollHandDrag)
    elif event.button() == Qt.RightButton and self.choice==0:
        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
    elif event.button() == Qt.RightButton and self.choice==1:
        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()  
    print(self.x2)
    print(self.y2) 
    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 and self.choice==0:
        global croppedFname
        croppedFname=''
        self.changeRubberBand = False
        currentQRect = self.rubberBand.geometry()
        outputimg=QtGui.QPixmap(self.x2-self.x1, self.y2-self.y1)
        painter=QtGui.QPainter(outputimg)
        self.render(painter, source=currentQRect, mode=QtCore.Qt.KeepAspectRatio)
        outputimg.save('/home/sounak/Desktop/1.jpg')
        painter.end()
        if self.x1==self.x2 or self.y1==self.y2:
            croppedFname=''
        else:
            croppedFname='/home/sounak/Desktop/1.jpg'
        self.setDragMode(QtGui.QGraphicsView.NoDrag)
    elif event.button() == Qt.RightButton and self.choice==1:
        self.changeRubberBand = False
        currentQRect = self.rubberBand.geometry()
        self.setDragMode(QtGui.QGraphicsView.NoDrag)