如果在 ReadOnly State 中单击 QlineEdit 并根据 QlineEdit 是否在 ReadOnly state 中更改按钮颜色，请通知我们

Question

I have a Pyqt Widget containing 3 buttons, 1 QlineEdit and 1 statusbar. One of the buttons makes the qlineedit in Read Only state, another one to disable the qlineedit Readonly state and the last one to show the values of the Qlineedit in the status bar message.

I would like to build an event that is triggered when the qlineedit is in read only state and is clicked, this should show us a message in a status bar that the field is protected.

Lastly, I would like to build another event that changes the color of the button "Edit" When the Each Time the Qlineedit Read only State is disabled.

    ```
    
import sys
from PyQt5 import QtCore, QtWidgets
from PyQt5.QtWidgets import QMainWindow, QWidget, QLabel, QLineEdit
from PyQt5.QtWidgets import QPushButton, QStatusBar
from PyQt5.QtCore import QSize    

class MainWindow(QMainWindow):
    def __init__(self):
        QMainWindow.__init__(self)

        self.setMinimumSize(QSize(750, 300))    
        self.setWindowTitle("PyQt Line Edit example (textfield) - pythonprogramminglanguage.com") 

        self.nameLabel = QLabel(self)
        self.nameLabel.setText('Name:')
        self.line = QLineEdit(self)

        self.line.move(80, 20)
        self.line.resize(200, 32)
        self.nameLabel.move(20, 20)


        # Push buttons      


        self.btn_add = QPushButton('View', self)
        self.btn_add.clicked.connect(self.view)
        self.btn_add.resize(200,32)
        self.btn_add.move(80, 60)       


        self.btn_edit = QPushButton('Edit', self)
        self.btn_edit.clicked.connect(self.edit)



        if self.edit():
            self.btn_edit.clicked.connect(self.change_edit_button_color) #<<<<<<<<<<< This is my attempt
        ##  The problem is It doesn´t get disabled when I press other button

        else:
            self.btn_edit.clicked.connect(self.normal_edit_button_color)     


        self.btn_edit.resize(200,32)
        self.btn_edit.move(80, 120 )


        self.btn_Validate = QPushButton('Validate', self)
        self.btn_Validate.clicked.connect(self.Validate)
        self.btn_Validate.resize(200,32)
        self.btn_Validate.move(80, 180) 


        #Creating the statusbar

        self.statusBar = QStatusBar()
        self.setStatusBar(self.statusBar)




        self.line.setReadOnly(True)   #<<<< BY DEFAULT THE QLINE FIELD IS IN READONLY STATE


        #>>>>>>>>>>>>>>>If the Qlineedit object is in readonly state notify us>>> This is my attempt <<<<<<<<<<<<<<<<<<<<<<<<<
        #The problem is that it doesn´t take into account the if statetment


        if self.line.isReadOnly():

            self.line.selectionChanged.connect(self.Protected_field)



       






    def view(self):

        self.line.setReadOnly(True)   #<<<< FUCTION TO PROTECT THE QLINE FIELD BY READONLY STATE
        self.edit= False




    def edit(self):

        self.line.setReadOnly(False)       #<<<< FUCTION TO DISABLE READONLY STATE THE QLINE FIELD 
        return True

        


    def Validate(self):
        self.statusBar.showMessage("Qline Value is {}".format(self.line.text()), 8000)
        self.edit= False


    def Protected_field(self):       #<<<  show in statusbar a message when  the Qline is in Readonly state and is clicked

        self.statusBar.showMessage("This field is protected", 2000)

    def change_edit_button_color(self):        #<<<  Function to change edit button color when the QLINE is not in Readonly State

        self.btn_edit.setStyleSheet('background-color :rgb(119, 120, 121)')   

    def normal_edit_button_color(self):        #<<<  Function to change edit button color when the QLINE is not in Readonly State

        self.btn_edit.setStyleSheet('background-color :white')    



if __name__ == "__main__":
    app = QtWidgets.QApplication(sys.argv)
    mainWin = MainWindow()
    mainWin.show()
    sys.exit( app.exec_() )
    
    ´´´
    

I created the signal "selectionChanged" to notify us each time the Qlineedit object is clicked with an if statement but it doesn´t take that if statement into account, it triggers always the signal.

For the color change, I made the edit method return a boolean True value when it's clicked and the other buttons return False and created an if statement with the signal to change the button color each time the Edit method returns True, but the problem is the button doesn´t comeback to the normal color once the the boolean value is False.

Answer 1

There is no need to create additional slots for the same signal, you can simply change the color of the button inside the methods that toggle the readOnly setting. In fact you actually don't even need two separate buttons for the view and edit methods... you could just have a single button that toggles readOnly both off and on.

Also your if statement for the statusbar message isn't working because the code needs to be executed every time the button is pressed, so it needs to moved inside of the slot method.

For example:

class MainWindow(QMainWindow):
    def __init__(self):
        QMainWindow.__init__(self)
        self.setMinimumSize(QSize(750, 300))
        self.setWindowTitle("PyQt Line Edit example (textfield) - pythonprogramminglanguage.com")
        self.nameLabel = QLabel(self)
        self.nameLabel.setText('Name:')
        self.line = QLineEdit(self)
        self.line.move(80, 20)
        self.line.resize(200, 32)
        self.nameLabel.move(20, 20)
        self.btn_add = QPushButton('View', self)
        self.btn_add.clicked.connect(self.view)
        self.btn_add.resize(200,32)
        self.btn_add.move(80, 60)
        self.btn_edit = QPushButton('Edit', self)
        self.btn_edit.clicked.connect(self.edit)
        self.btn_edit.resize(200,32)
        self.btn_edit.move(80, 120 )
        self.btn_Validate = QPushButton('Validate', self)
        self.btn_Validate.clicked.connect(self.Validate)
        self.btn_Validate.resize(200,32)
        self.btn_Validate.move(80, 180)
        self.statusBar = QStatusBar()
        self.setStatusBar(self.statusBar)
        self.line.setReadOnly(True)
        self.line.selectionChanged.connect(self.Protected_field)

    def view(self):
        self.line.setReadOnly(True)
        self.btn_edit.setStyleSheet('background-color: rgb(119, 120, 121);')

    def edit(self):
        self.line.setReadOnly(False)
        self.btn_edit.setStyleSheet('background-color :white')

    def validate(self):
        self.statusBar.showMessage("Qline Value is {}".format(self.line.text()), 8000)

    def protected_field(self):
        if self.line.isReadOnly():
            self.statusBar.showMessage("This field is protected", 2000)

I also suggest using a vertical layout instead of calling move and resize on each widget. Check out QVBoxLayout .