Replace rectangle of a QPixmap with another when using QGraphicsPixmapItem PYQT

Question

I have a scene with QGraphicsPixmapItem, and show a QGraphicScene object like a rectangle.

    def setupUI(self):
        self.pixmap01 = QPixmap.fromImage(qImg)
        self.mainpic = QGraphicsPixmapItem(self.pixmap01)
        self.scene1.addItem(self.mainpic)
        self.graphicsViewScene1.setScene(self.scene1)
        self.scene1.update()

    def DrawRectangle(self):
        scene = RectangleScene()
        scene.addItem(self.mainpic)
        self.graphicsViewScene1.setScene(scene)

Now i a draw rectangle and top of a scene(this part of code is fine) but after right click on rect and choose replace pic item(option menu) i want to replace this selected area of QPixmap with another QPixmap(for this action i use Qpainter but nothing happens)

class RectangleScene(QGraphicsScene):
    def __init__(self, *args, **kwargs):
        super(RectangleScene, self).__init__(*args, **kwargs)

    def mousePressEvent(self, event):
        self.clean_scene()
        self.start_point = event.scenePos()
        self.end_point =self.start_point
        self.graphics_line = QGraphicsRectItem(QRectF(self.start_point, self.end_point))
        self.update_path()

    def mouseMoveEvent(self, event):
        self.end_point = event.scenePos()
        self.update_path()

    def mouseReleaseEvent(self, event):
        self.end_point = event.scenePos()
        self.update_path()

    def update_path(self):     
        self.graphics_line.setRect(QRectF(self.start_point, self.end_point))
        self.addItem(self.graphics_line)

    def contextMenuEvent(self, event):
        menu = QtWidgets.QMenu()
        f1 = menu.addAction("repalce pic")
        if action == f1: 
           tmp_rect = QRectF(self.start_point, self.end_point)
           new_pix_map = QPixmap.fromImage(qImg)
           painter = QPainter(self.imageProcessing.pixmap01)
           painter.drawPixmap(tmp_rect,new_pix_map ,tmp_rect)

in another part of code after select this area, get a ndarray of this area and add some filters then i want to add top of this rect