如何从主窗口（父窗口）向子窗口发送自定义信号？

Question

如何从父窗口/主窗口向子窗口发送信号？你知道吗

例如，如何注册并将mainSignal发送到widgetA或widgetB？你知道吗

from PyQt5 import QtCore, QtGui, QtWidgets


class widgetB(QtWidgets.QWidget):

    procDone = QtCore.pyqtSignal(str)

    def __init__(self, parent=None):
        super(widgetB, self).__init__(parent)

        self.lineEdit = QtWidgets.QLineEdit(self)
        self.button = QtWidgets.QPushButton("Send Message to A", self)
        self.layout = QtWidgets.QHBoxLayout(self)
        self.layout.addWidget(self.lineEdit)
        self.layout.addWidget(self.button)

        self.button.clicked.connect(self.on_button_clicked)

    @QtCore.pyqtSlot()
    def on_button_clicked(self):
        self.procDone.emit(self.lineEdit.text())

    @QtCore.pyqtSlot(str)
    def on_procStart(self, message):
        self.lineEdit.setText("From A: " + message)

        self.raise_()


class widgetA(QtWidgets.QWidget):
    procStart = QtCore.pyqtSignal(str)

    def __init__(self, parent=None):
        super(widgetA, self).__init__(parent)

        self.lineEdit = QtWidgets.QLineEdit(self)
        self.lineEdit.setText("Hello!")

        self.button = QtWidgets.QPushButton("Send Message to B", self)
        self.button.clicked.connect(self.on_button_clicked)

        self.layout = QtWidgets.QHBoxLayout(self)
        self.layout.addWidget(self.lineEdit)
        self.layout.addWidget(self.button)

    @QtCore.pyqtSlot()
    def on_button_clicked(self):
        self.procStart.emit(self.lineEdit.text())

    @QtCore.pyqtSlot(str)
    def on_widgetB_procDone(self, message):
        self.lineEdit.setText("From B: " + message)

        self.raise_()


class mainwindow(QtWidgets.QMainWindow):
    mainSignal = QtCore.pyqtSignal(str)

    def __init__(self, parent=None):
        super(mainwindow, self).__init__(parent)

        self.button = QtWidgets.QPushButton("Click Me", self)
        self.button.clicked.connect(self.on_button_clicked)

        self.setCentralWidget(self.button)

        self.widgetA = widgetA()
        self.widgetB = widgetB()

        self.widgetA.procStart.connect(self.widgetB.on_procStart)
        self.widgetB.procDone.connect(self.widgetA.on_widgetB_procDone)

    @QtCore.pyqtSlot()
    def on_button_clicked(self):
        self.widgetA.show()
        self.widgetB.show()

        self.widgetA.raise_()


if __name__ == "__main__":
    import sys

    app = QtWidgets.QApplication(sys.argv)
    main = mainwindow()
    main.show()
    sys.exit(app.exec_())

Answer 1

逻辑是一样的，在这里，它们是否是父对象、子对象等都无关紧要。只需要两个对象可以同时访问。信号和插槽的设计使得类是独立的。你知道吗

from PyQt5 import QtCore, QtGui, QtWidgets


class widgetB(QtWidgets.QWidget):

    procDone = QtCore.pyqtSignal(str)

    def __init__(self, parent=None):
        super(widgetB, self).__init__(parent)

        self.lineEdit = QtWidgets.QLineEdit(self)
        self.button = QtWidgets.QPushButton("Send Message to A", self)
        self.layout = QtWidgets.QHBoxLayout(self)
        self.layout.addWidget(self.lineEdit)
        self.layout.addWidget(self.button)

        self.button.clicked.connect(self.on_button_clicked)

    @QtCore.pyqtSlot()
    def on_button_clicked(self):
        self.procDone.emit(self.lineEdit.text())

    @QtCore.pyqtSlot(str)
    def on_procStart(self, message):
        self.lineEdit.setText("From A: " + message)

        self.raise_()

    @QtCore.pyqtSlot(str)
    def on_message_from_main(self, text):
        self.lineEdit.setText("From Main: " + text)

class widgetA(QtWidgets.QWidget):
    procStart = QtCore.pyqtSignal(str)

    def __init__(self, parent=None):
        super(widgetA, self).__init__(parent)

        self.lineEdit = QtWidgets.QLineEdit(self)
        self.lineEdit.setText("Hello!")

        self.button = QtWidgets.QPushButton("Send Message to B", self)
        self.button.clicked.connect(self.on_button_clicked)

        self.layout = QtWidgets.QHBoxLayout(self)
        self.layout.addWidget(self.lineEdit)
        self.layout.addWidget(self.button)

    @QtCore.pyqtSlot()
    def on_button_clicked(self):
        self.procStart.emit(self.lineEdit.text())

    @QtCore.pyqtSlot(str)
    def on_widgetB_procDone(self, message):
        self.lineEdit.setText("From B: " + message)
        self.raise_()

    @QtCore.pyqtSlot(str)
    def on_message_from_main(self, text):
        self.lineEdit.setText("From Main: " + text)


class mainwindow(QtWidgets.QMainWindow):
    mainSignal = QtCore.pyqtSignal(str)

    def __init__(self, parent=None):
        super(mainwindow, self).__init__(parent)

        self.button = QtWidgets.QPushButton("Click Me", self)
        self.button.clicked.connect(self.on_button_clicked)

        self.setCentralWidget(self.button)

        self.widgetA = widgetA()
        self.widgetB = widgetB()

        self.widgetA.procStart.connect(self.widgetB.on_procStart)
        self.widgetB.procDone.connect(self.widgetA.on_widgetB_procDone)

        self.mainSignal.connect(self.widgetA.on_message_from_main)
        self.mainSignal.connect(self.widgetB.on_message_from_main)

    @QtCore.pyqtSlot()
    def on_button_clicked(self):
        self.widgetA.show()
        self.widgetB.show()

        self.widgetA.raise_()

        self.mainSignal.emit("Hello")


if __name__ == "__main__":
    import sys

    app = QtWidgets.QApplication(sys.argv)
    main = mainwindow()
    main.show()
    sys.exit(app.exec_())