[FIXED] PyQt5 QGraphicsView object has no attribute 'resetMatrix'?

Issue

Consider this PyQT5 example, let's call it test.py (for me, behaves the same under both python2 and python3 on Ubuntu 18.04):

#!/usr/bin/env python
from __future__ import print_function

import sys, os
from PyQt5 import QtCore, QtWidgets, QtGui

class PhotoViewer(QtWidgets.QGraphicsView):
    def __init__(self, parent):
        super(PhotoViewer, self).__init__(parent)
        self.parent = parent
        #self.resetMatrix() # SO: 39101834, but "AttributeError: 'PhotoViewer' object has no attribute 'resetMatrix'"
        self.scale(1.0, 1.0)

class MainWindow(QtWidgets.QMainWindow):
    def __init__(self):
        QtWidgets.QMainWindow.__init__(self)
        self.setWindowTitle("test.py")
        self.setMinimumWidth(1000)
        self.setMinimumHeight(600)
        self.viewer = PhotoViewer(self)
        wid = QtWidgets.QWidget(self)
        self.setCentralWidget(wid)
        VBlayout = QtWidgets.QVBoxLayout()
        VBlayout.addWidget(self.viewer)
        wid.setLayout(VBlayout)

if __name__ == "__main__":
    app = QtWidgets.QApplication([])
    main = MainWindow()
    main.show()
    sys.exit(app.exec_())

If I run it as is, it runs fine, without a problem.

If I uncomment the commented self.resetMatrix() line, then the program fails with:

$ python test.py 
Traceback (most recent call last):
  File "test.py", line 29, in <module>
    main = MainWindow()
  File "test.py", line 20, in __init__
    self.viewer = PhotoViewer(self)
  File "test.py", line 11, in __init__
    self.resetMatrix() # SO: 39101834, but "AttributeError: 'PhotoViewer' object has no attribute 'resetMatrix'"
AttributeError: 'PhotoViewer' object has no attribute 'resetMatrix'

But this I find rather bizarre, because PhotoViewer inherits from QGraphicsView, calling PhotoViewer.scale() which is a QGraphicsView method is clearly not a problem - and How to reset the scale in QGraphicsView? documents that calling QGraphicsView()->resetMatrix() should be possible, and also it is documented for both:

• http://pyqt.sourceforge.net/Docs/PyQt4/qgraphicsview.html#resetMatrix
• http://pyqt.sourceforge.net/Docs/PyQt5/api/QtWidgets/qgraphicsview.html -> "The C++ documentation can be found here." -> https://doc.qt.io/qt-5/qgraphicsview.html#resetMatrix

What is the mistake I'm making - why cannot I call resetMatrix in this case; and what should I do to be able to call this function?

Solution

It seems that it is a bug of PyQt5, I have tested it with PySide2 and it works correctly. But there is a workaround, if you check the source code you see that the the resetMatrix() method calls only resetTransform() so it uses that method.

class PhotoViewer(QtWidgets.QGraphicsView):
    def __init__(self, parent):
        super(PhotoViewer, self).__init__(parent)
        self.parent = parent
        self.resetTransform() # self.resetMatrix()
        self.scale(1.0, 1.0)

Answered By - eyllanesc