Requirements

Setup

Example

fromPyQt5.QtWidgetsimportQApplication,QHBoxLayout,QTextEdit,QWidgetfrompyqt_line_number_widgetimportLineNumberWidgetclassMainWindow(QWidget):def__init__(self):super().__init__()self.__initUi()def__initUi(self):self.__te=QTextEdit()self.__te.textChanged.connect(self.__line_widget_line_count_changed)self.__lineWidget=LineNumberWidget(self.__te)lay=QHBoxLayout()lay.addWidget(self.__lineWidget)lay.addWidget(self.__te)self.setLayout(lay)def__line_widget_line_count_changed(self):ifself.__lineWidget:n=int(self.__te.document().lineCount())self.__lineWidget.changeLineCount(n)if__name__=="__main__":importsysapp=QApplication(sys.argv)mainWindow=MainWindow()mainWindow.show()app.exec()