PyQt - Using Qt Designer

Understanding Qt Designer

Qt Designer is a powerful visual tool provided by the Qt framework for designing and building user interfaces (UIs) quickly and efficiently. It provides a drag-and-drop interface for adding and configuring various widgets such as buttons, labels, text fields, and more. When combined with PyQt5, Qt Designer can streamline the process of designing UIs and generating Python code, reducing development time and effort significantly.

Qt Designer is typically included with the Qt framework installation. To use Qt Designer with PyQt5, ensure that you have PyQt5 installed on your system. You can launch Qt Designer from the command line by running the command −

designer

The Qt Designer window appears as below −

Creating a New UI

To create a new UI in Qt Designer, start by selecting the "File" menu and choosing "New Form." You can choose from various templates such as Dialog with Buttons Bottom, Main Window, Widget, etc., depending on the type of UI you want to design.

Designing the UI

After you have created a form you can begin designing the user interface (UI) by dragging widgets from the widget box onto the form. Qt Designer offers a selection of widgets that can be personalized and organized based on your needs. You have the flexibility to resize, move and align widgets using either your mouse or the layout tools, in Qt Designer.

Generating Python Code

After designing the UI, you can generate Python code from Qt Designer to integrate the UI with your PyQt5 application. In Qt Designer, select the "File" menu and choose "Save As..." to save the UI file (.ui) to your project directory.

The designed form is saved as demo.ui. This ui file contains XML representation of widgets and their properties in the design. This design is translated into Python equivalent by using pyuic5 command line utility. This utility is a wrapper for uic module of Qt toolkit. The usage of pyuic5 is as follows −

pyuic5 -x demo.ui -o demo.py

In the above command, -x switch adds a small amount of additional code to the generated Python script (from XML) so that it becomes a self-executable standalone application.

if __name__ == "__main__":
   import sys
   app = QtGui.QApplication(sys.argv)
   Dialog = QtGui.QDialog()
   ui = Ui_Dialog()
   ui.setupUi(Dialog)
   Dialog.show()
   sys.exit(app.exec_())

Output

The above code produces the following output −

The user can input data in input fields but clicking on Add button will not generate any action as it is not associated with any function. Reacting to user-generated response is called as event handling.

Advantages of Using Qt Designer

Qt Designer is a powerful tool for designing graphical user interfaces (GUIs) for applications built with the Qt framework. Here are several advantages of using Qt Designer −

• Visual Design − Qt Designer provides a visual interface for designing GUIs, allowing developers to drag and drop UI components like buttons, labels, text boxes, and more onto a canvas. This visual design approach makes it easy to create complex layouts without having to write code manually.
• Rapid Prototyping − With its drag-and-drop interface, Qt Designer facilitates rapid prototyping, enabling developers to quickly create mockups of their UI designs and iterate on them efficiently.
• Platform Independence − Qt is a cross-platform framework, and GUIs designed with Qt Designer are inherently platform-independent. This means that UIs created using Qt Designer will look and behave consistently across different operating systems, including Windows, macOS, Linux, and others.
• Integration with Qt Framework − Qt Designer seamlessly integrates with the Qt framework, allowing developers to easily connect UI components to application logic using signals and slots. This integration streamlines the development process and promotes clean separation of UI design and application logic.
• Custom Widget Support − Qt Designer supports the use of custom widgets, enabling developers to extend the functionality of their applications by integrating third-party or custom-designed UI components.
• Internationalization (i18n) Support − Qt Designer facilitates internationalization by providing tools for easily translating UI elements into different languages. This allows developers to create multilingual applications with minimal effort.
• Promotes MVC Architecture − Qt follows the Model-View-Controller (MVC) architecture, and Qt Designer encourages adherence to this pattern by promoting the separation of UI design (view) from application logic (controller/model). This separation enhances code maintainability and scalability.
• UI File Serialization − Qt Designer saves UI designs in XML-based.ui files, which can be easily serialized and deserialized. This file format is human-readable and can be version-controlled, facilitating collaboration among team members and enabling efficient management of UI design files.
• Integration with Qt Creator − Qt Designer is integrated into Qt Creator, the official IDE for Qt development. This integration provides a seamless workflow for designing UIs, coding application logic, debugging, and testing, all within a single development environment.
• Community and Resources − Qt has a vibrant community and extensive documentation, tutorials, and resources available online. Developers can leverage these resources to learn Qt Designer quickly, troubleshoot issues, and stay updated on best practices and tips for UI design with Qt.