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PyQt4 textbox

In this article you will learn how to interact with a textbox using PyQt4.

If you want to display text in a textbox (QLineEdit) you could use the setText() method.

Related course:

Create GUI Apps with PyQt5

PyQt4 QLineEdit

The textbox example below changes the text if the button is pressed.

import sys
from PyQt4.QtCore import pyqtSlot
from PyQt4.QtGui import *
 
# create our window
app = QApplication(sys.argv)
w = QWidget()
w.setWindowTitle('Textbox example @pythonspot.com')
 
# Create textbox
textbox = QLineEdit(w)
textbox.move(20, 20)
textbox.resize(280,40)
 
# Set window size.
w.resize(320, 150)
 
# Create a button in the window
button = QPushButton('Click me', w)
button.move(20,80)
 
# Create the actions
@pyqtSlot()
def on_click():
textbox.setText("Button clicked.")
 
# connect the signals to the slots
button.clicked.connect(on_click)
 
# Show the window and run the app
w.show()
app.exec_()

The text field is created with the lines:

textbox = QLineEdit(w)
textbox.move(20, 20)
textbox.resize(280,40)

The button (from screenshot) is made with:

button = QPushButton('Click me', w)

We connect the button to the on_click function by:

# connect the signals to the slots
button.clicked.connect(on_click)

This function sets the textbox using setText().

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Qt4 buttons

PyQt4 (Qt4) supports buttons through the QPushButton widget.

We extend the code to display a button in the center of the window.

The button will show a tooltip if hovered and when pressed will close the program.

Related course:

Create GUI Apps with PyQt5

PyQt4 button example

The example below adds a button to a PyQt4 window.

#! /usr/bin/env python
# -*- coding: utf-8 -*-
#
import sys
from PyQt4.QtGui import *
 
# Create an PyQT4 application object.
a = QApplication(sys.argv)
 
# The QWidget widget is the base class of all user interface objects in PyQt4.
w = QWidget()
 
# Set window size.
w.resize(320, 240)
 
# Set window title
w.setWindowTitle("Hello World!")
 
# Add a button
btn = QPushButton('Hello World!', w)
btn.setToolTip('Click to quit!')
btn.clicked.connect(exit)
btn.resize(btn.sizeHint())
btn.move(100, 80)
 
# Show window
w.show()
 
sys.exit(a.exec_())

PyQt4 signals and slots

A button click should do something. To do so, you must use signals and slots.

If a user does an action such as clicking on a button, typing text in a box – the widget sends out a signal. Signals can be connected with a slot, that acts as a receiver and acts on it.

import sys
from PyQt4.QtCore import pyqtSlot
from PyQt4.QtGui import *
 
# create our window
app = QApplication(sys.argv)
w = QWidget()
w.setWindowTitle('Button click example @pythonspot.com')
 
# Create a button in the window
btn = QPushButton('Click me', w)
 
# Create the actions
@pyqtSlot()
def on_click():
print('clicked')
 
@pyqtSlot()
def on_press():
print('pressed')
 
@pyqtSlot()
def on_release():
print('released')
 
# connect the signals to the slots
btn.clicked.connect(on_click)
btn.pressed.connect(on_press)
btn.released.connect(on_release)
 
# Show the window and run the app
w.show()
app.exec_()

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Qt4 window

In this tutorial you will learn how to create a graphical hello world application with PyQT4.

PyQT4, it is one of Pythons options for graphical user interface (GUI) programming.

Related course:

Create GUI Apps with PyQt5

PyQt4 window example:

This application will create a graphical window that can be minimized, maximimzed and resized it.

#! /usr/bin/env python
# -*- coding: utf-8 -*-
#
import sys
from PyQt4.QtGui import *
 
# Create an PyQT4 application object.
a = QApplication(sys.argv)
 
# The QWidget widget is the base class of all user interface objects in PyQt4.
w = QWidget()
 
# Set window size.
w.resize(320, 240)
 
# Set window title
w.setWindowTitle("Hello World!")
 
# Show window
w.show()
 
sys.exit(a.exec_())

The PyQT4 module must be immported, we do that with this line:

from PyQt4.QtGui import *

We create the PyQT4 application object using QApplication():

a = QApplication(sys.argv)

We create the window (QWidget), resize, set the tittle and show it with this code:

w = QWidget()
w.resize(320, 240)
w.setWindowTitle("Hello World!")

Don’t forget to show the window:

# Show window
w.show()

You can download a collection of PyQt4 examples:

Download PyQT Code (Bulk Collection)

QT4 Messagebox

PyQT4 offers message box functionality using several functions.
Messageboxes included in PyQT4 are: question, warning, error, information, criticial and about box.

Related course:

Create GUI Apps with PyQt5

PyQt4 mesagebox

The code below will display a message box with two buttons:

#! /usr/bin/env python
# -*- coding: utf-8 -*-
#
import sys
from PyQt4.QtGui import *
 
# Create an PyQT4 application object.
a = QApplication(sys.argv)
 
# The QWidget widget is the base class of all user interface objects in PyQt4.
w = QWidget()
 
# Show a message box
result = QMessageBox.question(w, 'Message', "Do you like Python?", QMessageBox.Yes | QMessageBox.No, QMessageBox.No)
 
if result == QMessageBox.Yes:
print 'Yes.'
else:
print 'No.'
 
# Show window
w.show()
 
sys.exit(a.exec_())

Result:

There are different types of messageboxes that PyQT4 provides.

PyQT4 Warning Box

You can display a warning box using this line of code:

QMessageBox.warning(w, "Message", "Are you sure you want to continue?")

PyQT4 Information box

We can display an information box using QMessageBox.information()

QMessageBox.information(w, "Message", "An information messagebox @ pythonspot.com ")

Result:

PyQT4 Critical Box

If something goes wrong in your application you may want to display an error message.

QMessageBox.critical(w, "Message", "No disk space left on device.")

Result:

PyQT4 About box

We have shown the question box above.

QMessageBox.about(w, "About", "An example messagebox @ pythonspot.com ")

Result:

Download PyQT Code (Bulk Collection)

Menu with PyQt4

PyQt4 menus appear in the top of the window bar. A menu gives the user control over the application and is often location in the top of the window.

The QMainWindow class creates the main application window. This class has a method named menuBar() which adds the title bar.

Menus can be added to the title bar using addMenu(). Inside each menu you can add a command using the addAction method.

Related course:

Create GUI Apps with PyQt5

PyQt4 menubar

This code will add a menu to your qt4 app:

#! /usr/bin/env python
# -*- coding: utf-8 -*-
#
import sys
from PyQt4.QtGui import *
 
# Create an PyQT4 application object.
a = QApplication(sys.argv)
 
# The QWidget widget is the base class of all user interface objects in PyQt4.
w = QMainWindow()
 
# Set window size.
w.resize(320, 240)
 
# Set window title
w.setWindowTitle("Hello World!")
 
# Create main menu
mainMenu = w.menuBar()
mainMenu.setNativeMenuBar(False)
fileMenu = mainMenu.addMenu('&amp;File')
 
# Add exit button
exitButton = QAction(QIcon('exit24.png'), 'Exit', w)
exitButton.setShortcut('Ctrl+Q')
exitButton.setStatusTip('Exit application')
exitButton.triggered.connect(w.close)
fileMenu.addAction(exitButton)
 
# Show window
w.show()
 
sys.exit(a.exec_())

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QT4 Widgets

We have various widgets that we can access with PyQT. Including:

Textbox
Combobox
Calendar

For more widgets we suggest using the GUI creation tool covered in the next tutorial.

Related course:

Create GUI Apps with PyQt5

Textbox widget
Input fields are present in nearly every application. In PyQT4 an input field can be created using the QLineEdit() function.

#! /usr/bin/env python
# -*- coding: utf-8 -*-
#
import sys
from PyQt4.QtGui import *
 
# Create an PyQT4 application object.
a = QApplication(sys.argv)
 
# The QWidget widget is the base class of all user interface objects in PyQt4.
w = QMainWindow()
 
# Set window size.
w.resize(320, 100)
 
# Set window title
w.setWindowTitle("PyQT Python Widget!")
 
# Create textbox
textbox = QLineEdit(w)
textbox.move(20, 20)
textbox.resize(280,40)
 
# Show window
w.show()
 
sys.exit(a.exec_())

Combobox
A combobox can be used to select an item from a list.

#! /usr/bin/env python
# -*- coding: utf-8 -*-
#
import sys
from PyQt4.QtGui import *
 
# Create an PyQT4 application object.
a = QApplication(sys.argv)
 
# The QWidget widget is the base class of all user interface objects in PyQt4.
w = QMainWindow()
 
# Set window size.
w.resize(320, 100)
 
# Set window title
w.setWindowTitle("PyQT Python Widget!")
 
# Create combobox
combo = QComboBox(w)
combo.addItem("Python")
combo.addItem("Perl")
combo.addItem("Java")
combo.addItem("C++")
combo.move(20,20)
 
# Show window
w.show()
 
sys.exit(a.exec_())

Calendar widget
The PyQT4 library has a calendar widget, you can create it using the QCalendarWidget() call.

#! /usr/bin/env python
# -*- coding: utf-8 -*-
#
import sys
from PyQt4.QtGui import *
 
# Create an PyQT4 application object.
a = QApplication(sys.argv)
 
# The QWidget widget is the base class of all user interface objects in PyQt4.
w = QMainWindow()
 
# Set window size.
w.resize(320, 240)
 
# Set window title
w.setWindowTitle("PyQT Python Widget!")
 
# Create calendar
cal = QCalendarWidget(w)
cal.setGridVisible(True)
cal.move(0, 0)
cal.resize(320,240)
 
# Show window
w.show()
 
sys.exit(a.exec_())

Result:

Download PyQT Code (Bulk Collection)

1 2 3

PyQt4 QLineEdit

PyQt4 button example

PyQt4 signals and slots

PyQt4 window example:

PyQt4 mesagebox

PyQT4 Warning Box

PyQT4 Information box

PyQT4 Critical Box

PyQT4 About box

PyQt4 menubar

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