PyQt5-Introduction

Qt is a C++ framework for creating native-looking GUI application in desktop or mobile or any other platform. PyQt5 is a Python wrapper for Qt.

This is an simple introduction on how to create GUI application in Python.

PyQt5 Installation

Use pip installation, (use one of the which it works)

pip install PyQt5
pip3 install PyQt5

Or use Anaconda Installation

conda install -c anaconda pyqt

Download Qt

Download Qt here, choosng the open source version is enough.

Qt Designer

Use Qt Designer (not Qt Creator) to drag-and-drop design UI elements. Qt Designer will save your file in .ui format. Use the following command in conda or windows commnad line to make a .py class file

pyuic5 FILENAME.ui -o FILENAME.py

Python GUI class

In the .py class there would be a class like this

from PyQt5 import QtCore, QtGui, QtWidgets

class Ui_MainWindow(object):
    def setupUi(self, MainWindow):
        MainWindow.setObjectName("MainWindow")
        MainWindow.resize(800, 600)
        self.centralwidget = QtWidgets.QWidget(MainWindow)
        self.centralwidget.setObjectName("centralwidget")
        self.pushButton = QtWidgets.QPushButton(self.centralwidget)
        self.pushButton.setGeometry(QtCore.QRect(330, 250, 121, 51))
        self.pushButton.setObjectName("pushButton")
        MainWindow.setCentralWidget(self.centralwidget)
        self.statusbar = QtWidgets.QStatusBar(MainWindow)
        self.statusbar.setObjectName("statusbar")
        MainWindow.setStatusBar(self.statusbar)

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

    def retranslateUi(self, MainWindow):
        _translate = QtCore.QCoreApplication.translate
        MainWindow.setWindowTitle(_translate("MainWindow", "MainWindow"))
        self.pushButton.setText(_translate("MainWindow", "PushButton"))

Starting the GUI object

To run the GUI class, you can use the following code

import sys, os

if __name__ == "__main__":
    # Safe start for Spyder IDE
    app = QtCore.QCoreApplication.instance()
    if app is None:
        app = QtWidgets.QApplication(sys.argv)

    # Initialize and run Qt UI        
    MainWindow = QtWidgets.QMainWindow()
    ui = Ui_MainWindow()
    ui.setupUi(MainWindow)
    MainWindow.show()

    # Exiting UI
    if any('SPYDER' in name for name in os.environ):
        # Safe exit for Spyder IDE
        app.exec_()
    else:        
        sys.exit(app.exec_())

Connect function call to a button

To connect function button when a button onClick

def retranslateUi(self, MainWindow):
    self.pushButton.clicked.connect(lambda: self.Quick_Demo("test_String"))

def Quick_Demo(self, str):
    print("Quick Demo %s"%(str))

Pyinstaller

You may want to build your Python script to an executable so that people can run it directly without setting up the environments.

Pyinstaller installation and usage

To install

pip install pyinstaller

To run pyinstaller

pyinstaller <YOUR_SCRIPY>.py

Useful options

--noconsole The executable would not open up the Python console

--onefile (default is --onedir) Instead of spanning all the libraries in a folder (and the .exe can only be executed in that folder), create a one-file bundled executable.

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