Signals and slots are PyQt mechanism for communication between programming objects. Every inherited from QWideget controls are supported signals and slots mechanism. When the signal transmission (transmission request), the slot function is performed automatically connected (processing request). This paper describes the basic signals and slots, the most frequently used method. And a built-in signal is used to use grooves.

Built-in signal and slots

The so-called built-in signal used slots. Refers to when the transmitted signal, using the window control function, instead of the custom functions. The method of connecting the signal channel is connected to a signal QObject slot function by another QObject QObject.signal.connect.

In any GUI design, the button is the most important and commonly used trigger action request way to interact with the user. Common buttons include QPushButton, QRadioButton and QCheckBox. These buttons are inherited from QAbstractButton class, QAbstractButton signals include:

Clicked : Click the left mouse button and release the trigger signal. Most used. Remember this almost enough.

Pressed: The trigger signal when the left mouse button pressed

Released: The trigger signal when the left mouse button is released

Toggled: The trigger signal when the control tag changes state.

Example built-in signal and slots

Click here to implement a button to exit the interface implementation process needs to introduce built-in signal and slots. He started working. . .

Step1: Open Qt Designer, select the Widget Templates. In the toolbox drag Push Button control buttons to the main screen. And modify the control display name. Save as singal.ui. Interface is as follows:

Step2: Use pyuic5 -o singal.py singal.ui .py converted format.

Step3: to consider the convenience of presentation, the program will be called in the main program in singal.py. Which MyMainForm command line class Push Button Click the button to add the signal slot function. as follows

self.pushButton.clicked.connect(self.close)

Following complete code (direct copy operation, part of the font bold addition section):

# -*- coding: utf-8 -*-

# Form implementation generated from reading ui file 'signal.ui'
#
# Created by: PyQt5 UI code generator 5.11.3
#
# WARNING! All changes made in this file will be lost!

import sys
from PyQt5 import QtCore, QtGui, QtWidgets
from PyQt5.QtWidgets import QApplication, QMainWindow, QMessageBox

class Ui_Form(object):
    def setupUi(self, Form):
        Form.setObjectName("Form")
        Form.resize(431, 166)
        self.pushButton = QtWidgets.QPushButton(Form)
        self.pushButton.setGeometry(QtCore.QRect(160, 50, 91, 41))
        font = QtGui.QFont()
        font.setFamily("YaHei Consolas Hybrid")
        font.setPointSize(14)
        self.pushButton.setFont(font)
        self.pushButton.setObjectName("pushButton")

        self.retranslateUi(Form)
        QtCore.QMetaObject.connectSlotsByName(Form)

    def retranslateUi(self, Form):
        _translate = QtCore.QCoreApplication.translate
        Form.setWindowTitle(_translate("Form", "信号与槽"))
        self.pushButton.setText(_translate("Form", "关闭"))

class MyMainForm(QMainWindow, Ui_Form):
    def __init__(self, parent=None):
        super(MyMainForm, self).__init__(parent)
        self.setupUi(self)
        self.pushButton.clicked.connect(self.close)

if __name__ == "__main__":
    app = QApplication(sys.argv)
    myWin = MyMainForm()
    myWin.show()
    sys.exit(app.exec_())

Run and click the following button to close the window

Custom built-in signal and grooves Example

Like the above-described process steps to achieve. ShowMsg slot function as a custom function.

Signals and slots: self.pushButton.clicked.connect (self.showMsg)

Following complete code (direct copy operation, part of the font bold addition section):

# -*- coding: utf-8 -*-

# Form implementation generated from reading ui file 'signal.ui'
#
# Created by: PyQt5 UI code generator 5.11.3
#
# WARNING! All changes made in this file will be lost!
import sys
from PyQt5 import QtCore, QtGui, QtWidgets
from PyQt5.QtWidgets import QApplication, QMainWindow, QMessageBox

class Ui_Form(object):
    def setupUi(self, Form):
        Form.setObjectName("Form")
        Form.resize(431, 166)
        self.pushButton = QtWidgets.QPushButton(Form)
        self.pushButton.setGeometry(QtCore.QRect(160, 50, 91, 41))
        font = QtGui.QFont()
        font.setFamily("YaHei Consolas Hybrid")
        font.setPointSize(14)
        self.pushButton.setFont(font)
        self.pushButton.setObjectName("pushButton")

        self.retranslateUi(Form)
        QtCore.QMetaObject.connectSlotsByName(Form)

    def retranslateUi(self, Form):
        _translate = QtCore.QCoreApplication.translate
        Form.setWindowTitle(_translate("Form", "信号与槽"))
        self.pushButton.setText(_translate("Form", "运行"))

class MyMainForm(QMainWindow, Ui_Form):
    def __init__(self, parent=None):
        super(MyMainForm, self).__init__(parent)
        self.setupUi(self)
        self.pushButton.clicked.connect(self.showMsg)

    def showMsg(self):
        QMessageBox.information(self, "信息提示框", "OK,内置信号与自定义槽函数！")

if __name__ == "__main__":
    app = QApplication(sys.argv)
    myWin = MyMainForm()
    myWin.show()
    sys.exit(app.exec_())