New QPixmap seems to overlay old QPixmap

Question

I want to display some images on my GUI, first when I click on the button, to select first image, everything act normal, my image is displayed fitInView, but when I want to select the next image, dark magic happens.. my second image is not in center like the first one, is on top of the QGraphicsView, and also it seem like old image's QScenes doesn't disappear, I have the ScrollBar from risg and bottom and I can scrool until I have al blank on QGraphicsView, what is the problem? I can't figured out..

My code:

import sys
from PyQt5 import QtCore, QtGui, QtWidgets
# from PyQt4 import QtCore, QtWidgets

class Graph(QtWidgets.QGraphicsView):
        def __init__(self, parent=None):
            super(Graph, self).__init__(parent)
            scene = QtWidgets.QGraphicsScene(self)
            self.setScene(scene)
            self.pixmap = QtGui.QPixmap()
            self.m_pixmap_item = self.scene().addPixmap(self.pixmap)


        def setPixmap(self, _pixmap):
            self.pixmap = _pixmap
            # self.m_pixmap_item = self.scene().addPixmap(self.pixmap)
            self.m_pixmap_item.setPixmap(self.pixmap)
            self.fitInView(self.m_pixmap_item, QtCore.Qt.KeepAspectRatio)

        def resizeEvent(self, event):
            if not self.m_pixmap_item.pixmap().isNull():
                self.fitInView(self.m_pixmap_item, QtCore.Qt.KeepAspectRatio)
            super(Graph, self).resizeEvent(event)

mainwindow part:

class Window(QtWidgets.QWidget):
    def __init__(self):
        super(Window, self).__init__()
        self.setMinimumSize(640, 480)
        # --> Create Class ResizbleRubberBand <-> Parent: QLabel
        self.band = Graph(self)
        # --> Create buttons & functions
        self.fileOpen_btn = QtWidgets.QPushButton()
        self.create_and_format_btn(self.fileOpen_btn, self.fileOpen, 'GUI/icons/file.png', 32)
        btn_Layout = QtWidgets.QVBoxLayout()
        btn_layout_1 = QtWidgets.QHBoxLayout()
        btn_layout_1.addWidget(self.fileOpen_btn)
        btn_Layout.addLayout(btn_layout_1)
        layout = QtWidgets.QHBoxLayout(self)
        layout.setAlignment(QtCore.Qt.AlignCenter)
        layout.addWidget(self.band)
        layout.addLayout(btn_Layout)

    def create_and_format_btn(self, btn_name, btn_function, btn_icon, btn_iconsize):
        btn_name.clicked.connect(btn_function)
        btn_name.setIcon(QtGui.QIcon(btn_icon))
        btn_name.setIconSize(QtCore.QSize(btn_iconsize, btn_iconsize))

    def fileOpen(self):
        path = QtWidgets.QFileDialog.getOpenFileName(self, 'Open File')
        filename = path[0]
        self.loadImage_On_Pixmap(filename)

    def loadImage_On_Pixmap(self, file):
        f = QtGui.QPixmap(file)
        self.band.setPixmap(f)



if __name__ == '__main__':

    app = QtWidgets.QApplication(sys.argv)
    window = Window()
    # window.setGeometry(800, 100, 600, 500)
    window.show()
    sys.exit(app.exec_())

First Image (Normal):

Second Image (Strange):

Answer 1

Try it:

from PyQt5 import QtCore, QtGui, QtWidgets
from PyQt5.QtWidgets import QFileDialog


class PhotoViewer(QtWidgets.QGraphicsView):
    photoClicked = QtCore.pyqtSignal(QtCore.QPoint)

    def __init__(self, parent):
        super(PhotoViewer, self).__init__(parent)
        self._zoom = 0
        self._empty = True
        self._scene = QtWidgets.QGraphicsScene(self)
        self._photo = QtWidgets.QGraphicsPixmapItem()
        self._scene.addItem(self._photo)
        self.setScene(self._scene)
        self.setTransformationAnchor(QtWidgets.QGraphicsView.AnchorUnderMouse)
        self.setResizeAnchor(QtWidgets.QGraphicsView.AnchorUnderMouse)
        self.setVerticalScrollBarPolicy(QtCore.Qt.ScrollBarAlwaysOff)
        self.setHorizontalScrollBarPolicy(QtCore.Qt.ScrollBarAlwaysOff)
        self.setBackgroundBrush(QtGui.QBrush(QtGui.QColor(30, 30, 30)))
        self.setFrameShape(QtWidgets.QFrame.NoFrame)

    def hasPhoto(self):
        return not self._empty

    def fitInView(self, scale=True):
        rect = QtCore.QRectF(self._photo.pixmap().rect())
        if not rect.isNull():
            self.setSceneRect(rect)
            if self.hasPhoto():
                unity = self.transform().mapRect(QtCore.QRectF(0, 0, 1, 1))
                self.scale(1 / unity.width(), 1 / unity.height())
                viewrect = self.viewport().rect()
                scenerect = self.transform().mapRect(rect)
                factor = min(viewrect.width() / scenerect.width(),
                             viewrect.height() / scenerect.height())
                self.scale(factor, factor)
            self._zoom = 0

    def setPhoto(self, pixmap=None):
        self._zoom = 0
        if pixmap and not pixmap.isNull():
            self._empty = False
            self.setDragMode(QtWidgets.QGraphicsView.ScrollHandDrag)
            self._photo.setPixmap(pixmap)
        else:
            self._empty = True
            self.setDragMode(QtWidgets.QGraphicsView.NoDrag)
            self._photo.setPixmap(QtGui.QPixmap())
        self.fitInView()

    def wheelEvent(self, event):
        if self.hasPhoto():
            if event.angleDelta().y() > 0:
                factor = 1.25
                self._zoom += 1
            else:
                factor = 0.8
                self._zoom -= 1
            if self._zoom > 0:
                self.scale(factor, factor)
            elif self._zoom == 0:
                self.fitInView()
            else:
                self._zoom = 0

    def toggleDragMode(self):
        if self.dragMode() == QtWidgets.QGraphicsView.ScrollHandDrag:
            self.setDragMode(QtWidgets.QGraphicsView.NoDrag)
        elif not self._photo.pixmap().isNull():
            self.setDragMode(QtWidgets.QGraphicsView.ScrollHandDrag)

    def mousePressEvent(self, event):
        if self._photo.isUnderMouse():
            self.photoClicked.emit(QtCore.QPoint(event.pos()))
        super(PhotoViewer, self).mousePressEvent(event)


class Window(QtWidgets.QWidget):
    def __init__(self):
        super(Window, self).__init__()

        self.viewer = PhotoViewer(self)

        self.btnLoad = QtWidgets.QToolButton(self)
        self.btnLoad.setIcon(QtGui.QIcon('im.png'))
        self.btnLoad.setIconSize(QtCore.QSize(32, 32))
        self.btnLoad.clicked.connect(self.loadImage)

        layout = QtWidgets.QHBoxLayout(self)
        layout.addWidget(self.viewer)
        layout.addWidget(self.btnLoad)


    def loadImage(self):
        filename, _ = QtWidgets.QFileDialog.getOpenFileName(self, 'Open File')
        if filename:
            self.viewer.setPhoto(QtGui.QPixmap(filename))


if __name__ == '__main__':
    import sys
    app = QtWidgets.QApplication(sys.argv)
    window = Window()
    window.setGeometry(400, 100, 640, 480)
    window.show()
    sys.exit(app.exec_())