Menus and toolbars in PyQt4

In this part of the PyQt4 tutorial, we will create menus and toolbars. A menu is a group of commands located in a menubar. A toolbar has buttons with some common commands in the application.

Main window

The QtGui.QMainWindow class provides a main application window. This enables to create a classic application skeleton with a statusbar, toolbars, and a menubar.

Statusbar

A statusbar is a widget that is used for displaying status information.

#!/usr/bin/python
# -*- coding: utf-8 -*-

"""
ZetCode PyQt4 tutorial 

This program creates a statusbar.

author: Jan Bodnar
website: zetcode.com 
last edited: September 2011
"""

import sys
from PyQt4 import QtGui


class Example(QtGui.QMainWindow):
    
    def __init__(self):
        super(Example, self).__init__()
        
        self.initUI()
        
        
    def initUI(self):               
        
        self.statusBar().showMessage('Ready')
        
        self.setGeometry(300, 300, 250, 150)
        self.setWindowTitle('Statusbar')    
        self.show()


def main():
    
    app = QtGui.QApplication(sys.argv)
    ex = Example()
    sys.exit(app.exec_())


if __name__ == '__main__':
    main()

The statusbar is created with the help of the QtGui.QMainWindow widget.

self.statusBar().showMessage('Ready')

To get the statusbar, we call the statusBar() method of the QtGui.QMainWindow class. The first call of the method creates a status bar. Subsequent calls return the statusbar object. The showMessage() displays a message on the statusbar.

Menubar

A menubar is a common part of a GUI application. It is a group of commands located in various menus. (Mac OS treats menubars differently. To get a similar outcome, we can add the following line: menubar.setNativeMenuBar(False).)

#!/usr/bin/python
# -*- coding: utf-8 -*-

"""
ZetCode PyQt4 tutorial 

This program creates a menubar. The
menubar has one menu with an exit action.

author: Jan Bodnar
website: zetcode.com 
last edited: August 2011
"""

import sys
from PyQt4 import QtGui


class Example(QtGui.QMainWindow):
    
    def __init__(self):
        super(Example, self).__init__()
        
        self.initUI()
        
        
    def initUI(self):               
        
        exitAction = QtGui.QAction(QtGui.QIcon('exit.png'), '&Exit', self)        
        exitAction.setShortcut('Ctrl+Q')
        exitAction.setStatusTip('Exit application')
        exitAction.triggered.connect(QtGui.qApp.quit)

        self.statusBar()

        menubar = self.menuBar()
        fileMenu = menubar.addMenu('&File')
        fileMenu.addAction(exitAction)
        
        self.setGeometry(300, 300, 300, 200)
        self.setWindowTitle('Menubar')    
        self.show()
        
        
def main():
    
    app = QtGui.QApplication(sys.argv)
    ex = Example()
    sys.exit(app.exec_())


if __name__ == '__main__':
    main()    

In the above example, we create a menubar with one menu. This menu contains one action which terminates the application if selected. A statusbar is created as well. The action is accessible with the Ctrl+Q shortcut.

exitAction = QtGui.QAction(QtGui.QIcon('exit.png'), '&Exit', self)        
exitAction.setShortcut('Ctrl+Q')
exitAction.setStatusTip('Exit application')

A QtGui.QAction is an abstraction for actions performed with a menubar, toolbar or with a custom keyboard shortcut. In the above three lines, we create an action with a specific icon and an 'Exit' label. Furthermore, a shortcut is defined for this action. The third line creates a status tip which is shown in the statusbar when we hover a mouse pointer over the menu item.

exitAction.triggered.connect(QtGui.qApp.quit)

When we select this particular action, a triggered signal is emitted. The signal is connected to the quit() method of the QtGui.QApplication widget. This terminates the application.

menubar = self.menuBar()
fileMenu = menubar.addMenu('&File')
fileMenu.addAction(exitAction)

The menuBar() method creates a menubar. We create a file menu and append the exit action to it.

Toolbar

Menus group all commands that we can use in an application. Toolbars provide a quick access to the most frequently used commands.

#!/usr/bin/python
# -*- coding: utf-8 -*-

"""
ZetCode PyQt4 tutorial 

This program creates a toolbar.
The toolbar has one action, which
terminates the application if triggered.

author: Jan Bodnar
website: zetcode.com 
last edited: September 2011
"""

import sys
from PyQt4 import QtGui


class Example(QtGui.QMainWindow):
    
    def __init__(self):
        super(Example, self).__init__()
        
        self.initUI()
        
        
    def initUI(self):               
        
        exitAction = QtGui.QAction(QtGui.QIcon('exit24.png'), 'Exit', self)
        exitAction.setShortcut('Ctrl+Q')
        exitAction.triggered.connect(QtGui.qApp.quit)
        
        self.toolbar = self.addToolBar('Exit')
        self.toolbar.addAction(exitAction)
        
        self.setGeometry(300, 300, 300, 200)
        self.setWindowTitle('Toolbar')    
        self.show()
        
        
def main():
    
    app = QtGui.QApplication(sys.argv)
    ex = Example()
    sys.exit(app.exec_())


if __name__ == '__main__':
    main()

In the above example, we create a simple toolbar. The toolbar has one tool action. An exit action which terminates the application when triggered.

exitAction = QtGui.QAction(QtGui.QIcon('exit24.png'), 'Exit', self)
exitAction.setShortcut('Ctrl+Q')
exitAction.triggered.connect(QtGui.qApp.quit)

Similar to the menubar example above, we create an action object. The object has a label, icon and a shorcut. A quit() method of the QtGui.QMainWindow is connected to the triggered signal.

self.toolbar = self.addToolBar('Exit')
self.toolbar.addAction(exitAction)

Here we create a toolbar and plug and action object into it.

Toolbar
Figure: Toolbar

Putting it together

In the last example of this section, we create a menubar, a toolbar and a statusbar. We also create a central widget.

#!/usr/bin/python
# -*- coding: utf-8 -*-

"""
ZetCode PyQt4 tutorial 

This program creates a skeleton of
a classic GUI application with a menubar,
toolbar, statusbar and a central widget. 

author: Jan Bodnar
website: zetcode.com 
last edited: September 2011
"""

import sys
from PyQt4 import QtGui


class Example(QtGui.QMainWindow):
    
    def __init__(self):
        super(Example, self).__init__()
        
        self.initUI()
        
        
    def initUI(self):               
        
        textEdit = QtGui.QTextEdit()
        self.setCentralWidget(textEdit)

        exitAction = QtGui.QAction(QtGui.QIcon('exit24.png'), 'Exit', self)
        exitAction.setShortcut('Ctrl+Q')
        exitAction.setStatusTip('Exit application')
        exitAction.triggered.connect(self.close)

        self.statusBar()

        menubar = self.menuBar()
        fileMenu = menubar.addMenu('&File')
        fileMenu.addAction(exitAction)

        toolbar = self.addToolBar('Exit')
        toolbar.addAction(exitAction)
        
        self.setGeometry(300, 300, 350, 250)
        self.setWindowTitle('Main window')    
        self.show()
        
        
def main():
    
    app = QtGui.QApplication(sys.argv)
    ex = Example()
    sys.exit(app.exec_())


if __name__ == '__main__':
    main()    

This code example creates a skeleton of a classic GUI application with a menubar, toolbar, and a statusbar.

textEdit = QtGui.QTextEdit()
self.setCentralWidget(textEdit)

Here we create a text edit widget. We set it to be the central widget of the QtGui.QMainWindow. The central widget occupies all space that is left.

MainWindow
Figure: MainWindow

In this part of the PyQt4 tutorial, we worked with menus, toolbars, a statusbar, and a main application window.