Refactoring minimum code to use a class

The code on the previous tutorial worked, but it is better to program the window as a widget, using a class, so that the code is clearer and can be reused more easily.

We will create a class "PCBOutlineCreator" that will inherit from QWidget:

class PCBOutlineCreator(QtGui.QWidget):
    pass

On the constructor, we will call the parent's constructor, and we will define a function to load and setup the UI:

class PCBOutlineCreator(QtGui.QWidget):
    def __init__(self, parent=None):
        QtGui.QWidget.__init__(self, parent)

        self.setupUI()

    def setupUI():
        pass

In that function, we will first use the function defined in the previous chapter to load the UI file. That function will load the file as a QWidget, that we will place in the layout of our PCBOutlineCreator QWidget. For this window we will use a vertical layout.

    def setupUI(self):
        ui_file_path = os.path.join(os.path.realpath(os.path.dirname(__file__)), 'PCBOutlineCreator.ui')
        main_widget = load_ui(ui_file_path, self)
        layout = QtGui.QVBoxLayout()
        layout.addWidget(main_widget)
        self.setLayout(layout)

The last change to perform is to adapt the code of the main program:

if __name__ == '__main__':

    # Create Qt app
    app = QtGui.QApplication(sys.argv)

    # Create the widget and show it
    gui = PCBOutlineCreator()
    gui.show()

    # Run the app
    sys.exit(app.exec_())

In the next chapter we will learn how to access and configure all the different widgets in our window.

Complete code

from PySide import QtCore,QtGui
from PySide import QtUiTools
import os, sys

def load_ui(file_name, where=None):
    """
    Loads a .UI file into the corresponding Qt Python object
    :param file_name: UI file path
    :param where: Use this parameter to load the UI into an existing class (i.e. to override methods)
    :return: loaded UI
    """
    # Create a QtLoader
    loader = QtUiTools.QUiLoader()

    # Open the UI file
    ui_file = QtCore.QFile(file_name)
    ui_file.open(QtCore.QFile.ReadOnly)

    # Load the contents of the file
    ui = loader.load(ui_file, where)

    # Close the file
    ui_file.close()

    return ui

class PCBOutlineCreator(QtGui.QWidget):
    def __init__(self, parent=None):
        QtGui.QWidget.__init__(self, parent)
        self.setupUI()

    def setupUI(self):
        ui_file_path = os.path.join(os.path.realpath(os.path.dirname(__file__)), 'PCBOutlineCreator.ui')
        main_widget = load_ui(ui_file_path, self)
        layout = QtGui.QVBoxLayout()
        layout.addWidget(main_widget)
        self.setLayout(layout)


if __name__ == '__main__':

    # Create Qt app
    app = QtGui.QApplication(sys.argv)

    # Create the widget and show it
    gui = PCBOutlineCreator()
    gui.show()

    # Run the app
    sys.exit(app.exec_())