PyQt4 textbox

pyqt textbox
PyQt4 textbox example
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.

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You may like:

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 button example
PyQt4 button example
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.

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You may like:

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

pyqt window
PyQt4 window on Ubuntu
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.

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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:
 
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QT4 Messagebox

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

Related courses:

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:

qtMessagebox question
qtMessagebox question

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:

QMessageBox Info
QMessageBox Info

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:

QMessagebox
QMessagebox

PyQT4 About box

We have shown the question box above.

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

Result:

qt Messagebox
qt Messagebox

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Menu with PyQt4

PyQT Menu pythonspot
PyQT Menu
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 Simple GUI Applications with Python and Qt

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('&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 Simple GUI Applications with Python and Qt

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_())
qt textbox
qt textbox

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_())
qt combobox
qt combobox

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:

calendar qt
calendar qt

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