PyQt5 note 7 – multiple classes sharing signals

1. Signal transmission

• Custom signal in main window class and binding slot function in constructor
• Pass the object of the main window when instantiating the dialog class
• Customize the signal in the dialog box and bind the slot function in the constructor to the signal trigger function in the main window class
• When you want to execute the custom signal binding slot function in the main window class, as long as you trigger the custom signal in the current class, you can pass the signal up
• Multiple layers can be nested

import sys
from PyQt5.QtWidgets import QApplication, QMainWindow, QDialog, QPushButton
from PyQt5.QtCore import Qt, pyqtSignal


class MainWindow(QMainWindow):
    """
    //Main window class
    """
    my_signal = pyqtSignal()

    def __init__(self, *args):
        super(MainWindow, self).__init__(*args)

        # Set the title and size of the main window
        self.setWindowTitle('main window')
        self.resize(400, 300)

        # Create button
        self.btn = QPushButton(self)
        self.btn.setText('Pop up dialog')
        self.btn.clicked.connect(self.show_dialog)

        # Custom signal binding
        self.my_signal.connect(self.test)

        # Create dialog object
        self.dialog = Dialog(self)

    def show_dialog(self):
        self.dialog.show()
        self.dialog.exec()

    def test(self):
        self.btn.setText('I changed.')


class Dialog(QDialog):
    """
    //Dialog class
    """
    my_signal = pyqtSignal()

    def __init__(self, parent, *args):
        super(Dialog, self).__init__(*args)

        # Set the title and size of the dialog box
        self.setWindowTitle('Dialog box')
        self.resize(200, 200)
        self.setWindowModality(Qt.ApplicationModal)
        self.btn = QPushButton(self)
        self.btn.setText('Change the name of the main window button')
        self.btn.clicked.connect(self.my_signal.emit)

        # Custom signal binding
        self.my_signal.connect(parent.my_signal.emit)


if __name__ == '__main__':
    app = QApplication(sys.argv)
    demo = MainWindow()
    demo.show()
    sys.exit(app.exec())