Category: qt4

pyqt text box

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.

Related course:

Create GUI Apps with PyQt5

PyQt4 QLineEdit

The textbox example below changes the text if the button is pressed. Besides text, PyQt can show many more things like images with a qwidget or buttons with qpushbutton.


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().

Download PyQT Code (Bulk Collection)

qpushbutton signals

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.

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.

Note that these days, PyQt5 can be used to create a qpushbutton. Then use signals and slots to make it interactive.


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_()

Download PyQT Code (Bulk Collection)

Qt4 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.

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)

qt message box

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 Python 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:

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

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

PyQT4 About box

We have shown the question box above.

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

Result:

qt Messagebox

Download PyQT Code (Bulk Collection)

QT4 Table

We can show a table using the QTableWidget, part of the PyQt module. We set the title, row count, column count and add the data.

Related course:

Create GUI Apps with PyQt5

Qt4 Table example

An example below:

from PyQt4.QtGui import *
from PyQt4.QtCore import *
import sys

def main():
    app 	= QApplication(sys.argv)
    table 	= QTableWidget()
    tableItem 	= QTableWidgetItem()
    
    # initiate table
    table.setWindowTitle("QTableWidget Example @pythonspot.com")
    table.resize(400, 250)
    table.setRowCount(4)
    table.setColumnCount(2)
    
    # set data
    table.setItem(0,0, QTableWidgetItem("Item (1,1)"))
    table.setItem(0,1, QTableWidgetItem("Item (1,2)"))
    table.setItem(1,0, QTableWidgetItem("Item (2,1)"))
    table.setItem(1,1, QTableWidgetItem("Item (2,2)"))
    table.setItem(2,0, QTableWidgetItem("Item (3,1)"))
    table.setItem(2,1, QTableWidgetItem("Item (3,2)"))
    table.setItem(3,0, QTableWidgetItem("Item (4,1)"))
    table.setItem(3,1, QTableWidgetItem("Item (4,2)"))
    
    # show table
    table.show()
    return app.exec_()

if __name__ == '__main__':
    main()

Result:

PyQt Table

QTableWidget labels

You can set the header using the setHorizontalHeaderLabels() function. The same applies for vertical labels. A qt4 demonstration below:

from PyQt4.QtGui import *
from PyQt4.QtCore import *
import sys

def main():
    app 	= QApplication(sys.argv)
    table 	= QTableWidget()
    tableItem 	= QTableWidgetItem()
    
    # initiate table
    table.setWindowTitle("QTableWidget Example @pythonspot.com")
    table.resize(400, 250)
    table.setRowCount(4)
    table.setColumnCount(2)
    
    # set label
    table.setHorizontalHeaderLabels(QString("H1;H2;").split(";"))
    table.setVerticalHeaderLabels(QString("V1;V2;V3;V4").split(";"))
    
    # set data
    table.setItem(0,0, QTableWidgetItem("Item (1,1)"))
    table.setItem(0,1, QTableWidgetItem("Item (1,2)"))
    table.setItem(1,0, QTableWidgetItem("Item (2,1)"))
    table.setItem(1,1, QTableWidgetItem("Item (2,2)"))
    table.setItem(2,0, QTableWidgetItem("Item (3,1)"))
    table.setItem(2,1, QTableWidgetItem("Item (3,2)"))
    table.setItem(3,0, QTableWidgetItem("Item (4,1)"))
    table.setItem(3,1, QTableWidgetItem("Item (4,2)"))
    
    # show table
    table.show()
    return app.exec_()

if __name__ == '__main__':
    main()

Result:

PyQT Table

Note: These days you can use pyqt5 to create a pyqt table.

QTableWidget click events

We can detect cell clicks using this procedure, first add a function:

# on click function
table.cellClicked.connect(cellClick)

Then define the function:

def cellClick(row,col):
print "Click on " + str(row) + " " + str(col)

The Python programming language starts counting with 0, so when you press on (1,1) you will see (0,0). Full code to detect table clicks:

from PyQt4.QtGui import *
from PyQt4.QtCore import *
import sys

def cellClick(row,col):
    print "Click on " + str(row) + " " + str(col)

def main():
    app 	= QApplication(sys.argv)
    table 	= QTableWidget()
    tableItem 	= QTableWidgetItem()

    # initiate table
    table.setWindowTitle("QTableWidget Example @pythonspot.com")
    table.resize(400, 250)
    table.setRowCount(4)
    table.setColumnCount(2)
    
    # set label
    table.setHorizontalHeaderLabels(QString("H1;H2;").split(";"))
    table.setVerticalHeaderLabels(QString("V1;V2;V3;V4").split(";"))
    
    # set data
    table.setItem(0,0, QTableWidgetItem("Item (1,1)"))
    table.setItem(0,1, QTableWidgetItem("Item (1,2)"))
    table.setItem(1,0, QTableWidgetItem("Item (2,1)"))
    table.setItem(1,1, QTableWidgetItem("Item (2,2)"))
    table.setItem(2,0, QTableWidgetItem("Item (3,1)"))
    table.setItem(2,1, QTableWidgetItem("Item (3,2)"))
    table.setItem(3,0, QTableWidgetItem("Item (4,1)"))
    table.setItem(3,1, QTableWidgetItem("Item (4,2)"))
    
    # on click function
    table.cellClicked.connect(cellClick)
    
    # show table
    table.show()
    return app.exec_()

if __name__ == '__main__':
    main()

If you want to show the cell/row numbers in a non-programmer way use this instead:

def cellClick(row,col):
print "Click on " + str(row+1) + " " + str(col+1)

Tooltip text

We can set tooltip (mouse over) text using the method. If you set tooltips on non-existing columns you will get an error.

from PyQt4.QtGui import *
from PyQt4.QtCore import *
import sys

def main():
    app 	= QApplication(sys.argv)
    table 	= QTableWidget()
    tableItem 	= QTableWidgetItem()
    
    # initiate table
    table.setWindowTitle("QTableWidget Example @pythonspot.com")
    table.resize(400, 250)
    table.setRowCount(4)
    table.setColumnCount(2)
    
    # set label
    table.setHorizontalHeaderLabels(QString("H1;H2;").split(";"))
    table.setVerticalHeaderLabels(QString("V1;V2;V3;V4").split(";"))
    
    # set data
    table.setItem(0,0, QTableWidgetItem("Item (1,1)"))
    table.setItem(0,1, QTableWidgetItem("Item (1,2)"))
    table.setItem(1,0, QTableWidgetItem("Item (2,1)"))
    table.setItem(1,1, QTableWidgetItem("Item (2,2)"))
    table.setItem(2,0, QTableWidgetItem("Item (3,1)"))
    table.setItem(2,1, QTableWidgetItem("Item (3,2)"))
    table.setItem(3,0, QTableWidgetItem("Item (4,1)"))
    table.setItem(3,1, QTableWidgetItem("Item (4,2)"))
    
    # tooltip text
    table.horizontalHeaderItem(0).setToolTip("Column 1 ")
    table.horizontalHeaderItem(1).setToolTip("Column 2 ")
    
    # show table
    table.show()
    return app.exec_()

if __name__ == '__main__':
    main()

Result:

PyQT Table tooltips

Download PyQT Code (Bulk Collection)

open file python

In this short tutorial you will learn how to create a file dialog and load its file contents. The file dialog is needed in many applications that use file access.

Related course:

Create GUI Apps with PyQt5

File Dialog Example
To get a filename (not file data) in PyQT you can use the line:

filename = QFileDialog.getOpenFileName(w, 'Open File', '/')

If you are on Microsoft Windows use

filename = QFileDialog.getOpenFileName(w, 'Open File', 'C:\')

An example below (includes loading file data):

#! /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!")

# Get filename using QFileDialog
filename = QFileDialog.getOpenFileName(w, 'Open File', '/')
print(filename)

# print file contents
with open(filename, 'r') as f:
    print(f.read())

# Show window
w.show()

sys.exit(a.exec_())

Result (output may vary depending on your operating system):

PyQt File Open Dialog.

Download PyQT Code (Bulk Collection)

pyqt4

In this tutorial we will teach you how to create a graphical application with PyQT4. This will work on any platform that supports PyQT4 including Windows, Linux, UNIX, Android, OS X and iOS.

Related course:

Create GUI Apps with PyQt5

PyQt4 installation

PyQt does not include Qt itself – you may have to obtain it separately.
The homepage for PyQt is https://www.riverbankcomputing.com/software/pyqt/.

You will need to install some packages:


sudo pip install pyqt
sudo apt-get install qt4-designer
sudo apt-get install pyqt4-dev-tools
sudo apt-get install python-kde4

That should install qt4. If python-kde4 cannot be found update your repository to find it. If you are on Ubuntu use this link.

Building a PyQT4 GUI

Now we can use the QT Designer application. It saves us from writing tons of layout code that you may be used to when writing HTML. Start qt4-designer from your applications menu. The QT Designer application will appear.

QT Designer

Press Dialog without Buttons and press Create. You can now drag any component from the widget box to the form. Simple drag and drop. We added a button, label and a pixmap. (I took a random image from the web for the pixmap)

QT KDE Dialog

Our window looks like the image above. Press Form > Viewcode. We will get a popup box with the form code in… C++! That is great, but we want the Python code. Press File > Save as > form.ui.

The file test.ui contains your form described in XML format. (You can view it in a text editor) Open a console and type:


pyuic4 form.ui > form.py

Running the file does nothing. Create a new file called gui.py

Paste the code below:


import sys
from PyQt4 import QtCore, QtGui
from form import Ui_Dialog

class MyDialog(QtGui.QDialog):
    def __init__(self, parent=None):
        QtGui.QWidget.__init__(self, parent)
        self.ui = Ui_Dialog()
        self.ui.setupUi(self)

if __name__ == "__main__":
    app = QtGui.QApplication(sys.argv)
    myapp = MyDialog()
    myapp.show()
    sys.exit(app.exec_())

Run with:


python gui.py

This will open our qt4 graphical interface. Pressing on the OK button will simply close the application.

PyQt Window with QButton

We want to add some action when the OK button is pressed. We add these three lines to the code:


self.ui.pushButton.clicked.connect(self.OK)

def OK(self):
    print 'OK pressed.'

pyqt4 app example

Download PyQT4 Examples (Bulk Collection)

Category: qt4

pyqt text box

PyQt4 QLineEdit

qpushbutton signals

PyQt4 button example

PyQt4 signals and slots

Qt4 window

PyQt4 window example:

qt message box

PyQt4 mesagebox

PyQT4 Warning Box

PyQT4 Information box

PyQT4 Critical Box

PyQT4 About box

pyqt menu

pyqt widgets

QT4 Table

Qt4 Table example

QTableWidget labels

QTableWidget click events

Tooltip text

pyqt tabs

open file python

pyqt display image

progressbar python

python browser

pyqt4

PyQt4 installation

Building a PyQT4 GUI

pyqt qml