Tag: qt

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)

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

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pyqt menu

pyqt widgets

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_())