A Comparison of UI Frameworks
Most programming languages don't directly provide support for developing graphical user interfaces. It is typically done with external software that may be referred to as a library, toolkit or framework. Many such toolkits exist and are distinguished by a number of factors, most notably:
- What programming languages they directly support (e.g. C, C++, Python).
- What platforms they support (e.g. mobile, desktop, and embedded platforms such as Windows, Linux, macOS, iOS, and Android).
- Whether they also provide facilities beyond the user interface, like string handling, containers, file input/output, networking, etc.
- What type of license they are distributed under (e.g. open source/free software or commercial/proprietary).
The choice of a toolkit to use can be a daunting one. At ICS we use many different UI frameworks to implement applications with graphical user interfaces. Each has its pros and cons and the choice for a given application depends on a number of factors. I thought it would be interesting to compare the key features of some of the major UI frameworks or toolkits. To reduce the scope of the comparison to a manageable list, I tried to select only toolkits that some specific criteria:
- Run on multiple platforms
- Support native development
- Support using compiled languages
- Actively being maintained
I came up with 10 frameworks that met these criteria. The table below summarizes their features.
Framework Summary
| Name | Platforms | Languages | License | Pros | Cons | Comments |
| CopperSpice | Windows, Linux, macOS. | C++ | GPL / LGPL | Claimed performance improvements over Qt. Should be easy to port most Qt desktop code to it. | Desktop/widgets only. Small development team and user base. Not fully compatible with Qt. | Fork of Qt 4 that removes the need for moc and uses modern C++ features. |
| Crank Storyboard | Bare metal, various RTOS, VxWorks, Linux, macOS, Windows, Android. | C, C++ | Commercial | GUI builder. Lightweight (suitable for MCUs). | UI framework only. | Mainly used on MCU platforms. |
| Dear ImGui | Platforms that support DirectX, Metal, OpenGL, or Vulkan. | C++ | MIT | Lightweight. Leverages GPU for rendering. | Small development team, incomplete documentation. | Primary use cases are games and other applications with a 3D pipeline. |
| FLTK | X11, Windows, macOS. | C++ | LGPL | Lightweight, small, short learning curve. | UI framework only. Offers few widgets. Not native look and feel. | Mostly used on desktop platforms. |
| Flutter | Android, iOS, Linux, macOS, Windows, web. | Dart | BSD | Simple, short learning curve. | Only directly supports the Dart programming language. | Developed by Google. |
| GTK/gtkmm | X11, Wayland, Windows, macOS. | C, C++ | LGPL | Stable, widely used. | Lack of compatibility across major updates. | GTK uses C, gtmmm is the C++ interface. |
| Qt | Android, iOS, Linux, macOS, Windows, and others. | C++, QML, Python | GPL, LGPL, and commercial | Full cross-platform toolkit, large user base, well documented. | Large and complex. Long learning curve. | Need to decide whether to use widgets or QML. |
| Slint | Windows, Linux, macOS, and some MCUs. | C++, Rust, JavaScript | GPL or commercial | Lightweight, can run on MCUs. | Relatively new with a small user base. Limited MCU support. | QML-like markup language. |
| Unity | Windows, Linux, macOS, iOS, Android, and others. | C# | Commercial | 2D and 3D support on many platforms. Good documentation. | Closed source, commercial only. Only directly supports C# language (Mono on Linux). | Mostly targeted at game development. |
| WxWidgets | Windows, macOS, Linux. | C++ | LGPL-like | Stable, free. Uses native widgets when available. | Widgets-only, best suited to desktop applications. | Formerly known as WxWindows. |
Conclusions
Some of the information is subjective and the list is not exhaustive, but I hope it gives you some basis of comparison that can be helpful in selecting a toolkit or at least narrowing down the list of options to consider.