Change typing of page number in QPrinter

Question

How can I change the typing of the page number, for example: 1 of 4 if it contains 4 pages

    self.printer = QPrinter()
    self.printer.setPageSize(QPrinter.A4)
    self.printer.setOrientation(QPrinter.Portrait)
    self.printer.setFullPage(True)
    #self.printer.setPageMargins(20, 20, 20, 20, QPrinter.Millimeter)
    dialog = QtPrintSupport.QPrintDialog(self.printer)
    if dialog.exec_() == QtWidgets.QDialog.Accepted:
        self.preparationData(gnum)

I've used it via QTextDocument()