pyqt_code_delegate

import Ui_ImageSort # designed using Qt-Designer
from PyQt5 import QtCore
from PyQt5.QtWidgets import QMainWindow, QListWidgetItem

MaskRole = QtCore.Qt.UserRole + 1000

class ListDelegate(QtWidgets.QStyledItemDelegate):
    def createEditor(self, parent, option, index):
        mask = index.data(MaskRole)
        if mask is not None:
            editor = QtWidgets.QLineEdit(parent)
            editor.setInputMask(mask)
            return editor

    def setModelData(self, editor, model, index):
        if editor.hasAcceptableInput():
            text = editor.text()
            model.setData(index, text, QtCore.Qt.DisplayRole)

        re = QtCore.QRegularExpression(r"(\d+)\) (\d+) microns")
        match = re.match(index.data())
        color = QtGui.QColor("red")
        if match.hasMatch():
            val = match.captured(match.lastCapturedIndex())
            if val != "0":
                color = QtGui.QColor("black")
        model.setData(index, color, QtCore.Qt.ForegroundRole)

class ImageSort(Ui_ImageSort.Ui_MainWindow, QMainWindow):
    def __init__(self):
        super(ImageSort, self).__init__()
        self.setupUi(self)

    self.pushButton_1.clicked.connect(list_view)
    self.pushButton_2.clicked.connect(print_scales)

    def list_view(self):
        self.listWidget.clear()
        for i in range(len(self.scale_txt)):
            item = QListWidgetItem(str(self.scale_txt[i]))
            delegate = ListDelegate(self.listWidget)
            item.setData(MaskRole, "1)")
            item.setText("1)" + str(scale) + "microns")
            item.setFlags(item.flags() | QtCore.Qt.ItemIsEditable)
            item.setForeground(QtCore.Qt.red)
            self.listWidget.addItem(item)

    def print_scales(self):
        self.listWidget.clear()
        error = 0
        for i in range(len(self.scale_txt)):
            if (self.scale_txt[i]==0):
                error = 1

        if (error ==0):
            self.listWidget.addItem("\nThe scale values are confirmed ")
            for i in range(len(self.scale_txt)):
                    print(self.scale_txt[i])
                    print("\n")
        else:
            self.listWidget.addItem("\nThe scale values have an error")
            self.listWidget.addItem("Press button 1 again to edit")