Part 2 of PyQt 4 and Python 3 Crash Course

In this second part of the PyQt 4 and Python 3 crash course, we will continue exploring the different components and functionalities of PyQt 4. PyQt is a set of Python bindings for the Qt application framework developed by Riverbank Computing. Qt is a powerful and flexible framework for building cross-platform applications with a graphical user interface. PyQt allows you to create desktop applications that run on Windows, Mac, and Linux systems.

Before we get started, make sure you have PyQt 4 and Python 3 installed on your system. You can install PyQt 4 using pip:

pip install PyQt4

If you don’t have Python 3 installed, you can download it from the official Python website (https://www.python.org/).

Now, let’s dive into some more advanced topics in PyQt 4:

1. Creating Menus and Toolbars:

One of the key components of any desktop application is menus and toolbars. PyQt makes it easy to create menus and toolbars using the QMenuBar and QToolBar classes.

import sys
from PyQt4 import QtGui

class MyApp(QtGui.QMainWindow):
    def __init__(self):
        super(MyApp, self).__init__()

        self.initUI()

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

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

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

        self.setGeometry(300, 300, 300, 200)
        self.setWindowTitle('Menu and Toolbar')
        self.show()

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

if __name__ == '__main__':
    main()

In this example, we create a simple application with a menu and a toolbar. We create an action for exiting the application, add it to the menu, and connect it to the quit slot of the QApplication instance.

1. Working with dialogs:

Dialogs are another crucial component of desktop applications. PyQt provides several built-in dialogs for common tasks like opening files, selecting color or font, etc.

Let’s create a simple file dialog that allows the user to select a file:

import sys
from PyQt4 import QtGui

class MyApp(QtGui.QWidget):
    def __init__(self):
        super(MyApp, self).__init__()

        self.initUI()

    def initUI(self):

        self.btn = QtGui.QPushButton('Select File', self)
        self.btn.clicked.connect(self.showFileDialog)

        self.le = QtGui.QLineEdit(self)

        layout = QtGui.QVBoxLayout()
        layout.addWidget(self.btn)
        layout.addWidget(self.le)

        self.setLayout(layout)

        self.setGeometry(300, 300, 300, 200)
        self.setWindowTitle('File Dialog')
        self.show()

    def showFileDialog(self):
        fname = QtGui.QFileDialog.getOpenFileName(self, 'Open file', '/home')
        self.le.setText(fname)

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

if __name__ == '__main__':
    main()

In this example, we create a simple application with a button that opens a file dialog when clicked. The selected file path is displayed in a QLineEdit widget.

These are just a few examples of what you can achieve with PyQt 4. PyQt provides a wide range of classes and functionalities for building rich and interactive desktop applications. I encourage you to explore the PyQt documentation (https://www.riverbankcomputing.com/static/Docs/PyQt4) and experiment with different components to enhance your application’s user experience.

I hope this crash course has provided you with a solid foundation for working with PyQt 4 and Python 3. Happy coding!