History of Qt Software

History of Qt Software

Qt is a cross-platform software development framework that originated in the early 1990s. It was developed by Haavard Nord and Eirik Chambe-Eng in Norway and later commercialized through their company, Trolltech. Qt is widely used to develop graphical user interfaces (GUIs), but it also serves as a tool for non-GUI software, such as command-line tools and servers. The framework is written in C++ and offers language bindings for other languages such as Python (PyQt, PySide), Java, and others.

Trolltech was founded in 1994, and Qt was released to the public in 1995 under a proprietary license. In 2000, Qt became available under the GPL (General Public License), allowing developers to use it freely under open-source terms. Trolltech was acquired by Nokia in 2008, which resulted in significant changes in Qt’s development direction. After Nokia's exit from Qt, the software was transferred to Digia in 2011, which later split its Qt division into a separate company called The Qt Company in 2014.

Evolution of Qt Versions

Throughout the decades, Qt has seen major versions released, each bringing significant improvements in performance, features, and compatibility.

Qt 4 (Released in June 2005)

Qt 4 marked a significant evolution in the framework. One of the most important aspects of this version was that it streamlined the codebase, introducing a modular structure. This was particularly important for scaling the development of complex applications across multiple platforms.

Key features and improvements introduced in Qt 4 include:

- New Graphics Architecture: Qt 4 introduced the Graphics View Framework, which allowed for managing large numbers of 2D graphical items efficiently. This was a step forward in handling custom widgets and complex GUIs.

- Improved Performance: The framework underwent optimization for performance. Qt 4 reduced memory usage and enhanced rendering speed. Additionally, the introduction of new data containers and algorithms in its libraries helped make applications more responsive.

- Modular Design: Qt 4 broke down the monolithic structure of previous versions into multiple libraries, allowing developers to include only the components they needed.

- QML (Qt Meta-Object Language): Although QML would become more prevalent in Qt 5, the foundations for it began in Qt 4, emphasizing the move toward better support for declarative programming.

- New Features: Qt 4 also introduced model/view architecture for handling large data sets more efficiently, and the Phonon multimedia framework for handling audio and video playback.

Qt 5 (Released in December 2012)

Qt 5 was another major leap for the framework. It continued Qt’s tradition of multi-platform support but added extensive modernization, particularly in terms of graphics rendering and performance improvements.

Key features and improvements in Qt 5:

- Qt Quick and QML: Qt 5 focused heavily on Qt Quick, which uses QML to design user interfaces. Qt Quick is optimized for touchscreen devices and embedded systems, making Qt 5 a go-to choice for mobile development. The combination of QML and JavaScript provides a powerful way to create fluid and dynamic GUIs.

- Graphics Backend: One of the most significant changes in Qt 5 was the shift from raster-based rendering to hardware-accelerated rendering using OpenGL. This made it easier to create visually rich applications, particularly in embedded and mobile environments.

- Modularization: Qt 5 further refined the modularization introduced in Qt 4. This enabled developers to use smaller subsets of Qt, making it more flexible and lightweight, particularly useful for IoT and mobile devices.

- Multithreading: The framework saw substantial improvements in multithreading, allowing for better handling of concurrent tasks, essential for modern software.

- Cross-Platform Improvements: While earlier versions of Qt were primarily aimed at desktop platforms, Qt 5 added better support for mobile platforms like Android and iOS. It also maintained support for desktop platforms, including Linux, Windows, and macOS, and embraced embedded systems like Raspberry Pi.

- High DPI Support: Qt 5 was one of the first versions to offer support for high-DPI displays, allowing developers to create UIs that scaled smoothly on modern displays with high resolutions.

Qt 6 (Released in December 2020)

Qt 6 brought a fresh redesign under the hood, with a focus on modern C++ standards and making the framework future-proof for the years to come. It builds on Qt 5 but introduces significant changes that improve both performance and development ease.

Key features and improvements in Qt 6:

- C++17 Standard: Qt 6 embraced the C++17 standard, which provided many modern language features that simplify code and improve performance. Qt 6 codebases are cleaner, more efficient, and maintainable, leveraging newer C++ features like `std::variant`, `std::optional`, and `std::any`.

- Graphics Pipeline: Qt 6 made further advancements in graphics rendering by switching from OpenGL to Vulkan, Direct3D, and Metal backends. This change enables better cross-platform graphical performance and future-proofs the framework for newer hardware.

- Qt Quick 3D: A major addition in Qt 6 is Qt Quick 3D, which builds on the 2D Qt Quick but adds robust 3D scene rendering capabilities. It allows developers to create 3D interfaces and visualizations in the same way they create 2D ones.

- Enhanced Performance: Qt 6 introduced multiple improvements in memory consumption, reduced binary size, and enhanced rendering speed. The framework is optimized for embedded systems, desktop, and mobile platforms, including better support for Wayland on Linux.

- Multimedia Improvements: The multimedia module was revamped to support more modern backends and formats, further improving the ability to create media-rich applications.

- Unified Architecture: Qt 6 standardized many of the architectural differences that had arisen in Qt 5, providing a more consistent API across platforms and simplifying migration between different deployment targets.

- Improved Internationalization: The text shaping and layout engine in Qt 6 was updated to support more languages, writing systems, and localization features, making it a better fit for global applications.

Conclusion

Qt has evolved from a desktop-focused framework to a versatile toolkit for cross-platform development on desktop, mobile, and embedded devices. With each major version—Qt 4, Qt 5, and Qt 6—the framework has grown in power and flexibility. Qt 4 introduced the modular structure and improved performance. Qt 5 took a major leap with support for OpenGL, touchscreens, and mobile platforms. Finally, Qt 6 built on modern C++ standards, enhanced the graphics pipeline with support for Vulkan and other backends, and continued to refine performance for embedded and high-performance applications.

Each iteration has built on the legacy of providing developers with a flexible, high-performance framework that balances the need for cutting-edge features with ease of use across a variety of platforms.