Real Python: PyQt Layouts: Create Professional-Looking GUI Applications

PyQt’s layout managers provide a user-friendly and productive way of arranging graphical components, or widgets, on a GUI. Laying out widgets properly will make your GUI applications look polished and professional. Learning to do so efficiently and effectively is a fundamental skill for you to get up and running with GUI application development using Python and PyQt.

In this tutorial, you’ll learn:

• What the benefits are of using PyQt’s layout managers
• How to programmatically lay out widgets on a GUI using PyQt’s layout managers
• How to select the right layout manager for your GUI application
• How to lay out widgets in main window–based and dialog-based applications

With this knowledge and skillset, you’ll be able to use Python and PyQt to create professional-looking GUI applications.

For a better understanding of how to use layout managers, some previous knowledge of how to create PyQt GUI applications and how to work with PyQt widgets would be helpful.

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Laying Out Graphical Elements on a GUI

When you’re creating graphical user interface (GUI) applications, a common issue is how to get your graphical components—buttons, menus, toolbars, labels, and so on—laid out coherently on your forms and windows. This process is known as GUI layout, and it’s an important step in creating GUI applications.

In the past, if you wanted to lay out graphical components, or widgets, on a window, then you would follow one of the following approaches:

1. Decide on and manually set a static size and position for each widget on the window.
2. Calculate and set the size and position of each widget dynamically.

The first approach is fairly direct, but it has at least the following drawbacks:

• Your windows will be non-resizable, which might cause problems when displaying them on different screen resolutions.
• Your labels might not support localization properly because the length of a given text changes between languages.
• Your widgets will display differently on different platforms, which makes it difficult to write multiplatform applications that look good.

The second approach is more flexible. However, it also has drawbacks:

• You have to do a lot of manual calculations to determine the right size and position of each widget.
• You have to do some extra calculations to respond correctly to window resizing.
• You have to redo all the calculations any time you modify the layout of your window.

Even though you can still use either of these two approaches to lay out your GUIs, most of the time you’ll want to use a third and more convenient approach implemented by most modern GUI frameworks or toolkits: layout managers.

Note: In some GUI frameworks, such as Tkinter, layout managers are also referred to as geometry managers.

Layout managers automatically arrange widgets on a GUI according to your specific needs. They avoid the compatibility drawbacks of the first approach as well as the annoying and complicated calculations of the second approach.

In the following sections, you’ll learn about PyQt’s built-in layout managers and how to use them to effectively lay out the graphical components of your GUI applications.

Getting Stocked With a Gallery of PyQt Layouts

In PyQt, widgets are graphical components that you use as building blocks for your GUI applications. When you place a bunch of widgets on a window to create a GUI, you need to give them some order. You need to set the widgets’ size and position on the window, and you also need to define their behavior for when the user resizes the underlying window.

Note: Unfortunately, PyQt5’s official documentation has some incomplete sections. To work around this, you can check out the PyQt4 documentation, the Qt for Python documentation, or the original Qt documentation.

In this tutorial, you’ll find that most links will take you to the original Qt documentation, which is a better source of information in most cases.

To arrange the widgets on windows or forms in PyQt, you can use the following techniques:

• Use .resize() and .move() on your widgets to provide an absolute size and position.
• Reimplement .resizeEvent() and calculate your widgets’ size and position dynamically.
• Use layout managers and let them do all the calculations and hard work for you.

These techniques generally correspond to the three different approaches for laying out a GUI that you saw in the previous section.

Again, calculating the size and position dynamically might be a good approach, but most of the time you’ll be better off using layout managers. In PyQt, layout managers are classes that provide the required functionality to automatically manage the size, position, and resizing behavior of the widgets in the layout.

Read the full article at https://realpython.com/python-pyqt-layout/ »

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