Qt goes LGPL

The next release of Qt will be released under the LGPL license

Good news for people developing graphical applications for embedded Linux systems. Nokia, the new owners of Trolltech, announced they will release the next version of the Qt graphical library under the LGPL license. This means that developers will be able to create applications based on the Qt library, with the license of their choice, free software / open source or proprietary.

As we explained in our Choosing graphical libraries for embedded systems presentation, Qt is more than a graphical library. It also offers a complete development framework, with development tools, data structures, threads, networking, XML parsing utilities making application development easier. All these features, and the fact that Qt directly run on top of the Linux framebuffer, also make it possible to create systems with a feature-rich interface without having to drag and build numerous dependencies.

Another bonus is that Qt supports multiple operating systems, making your applications easily portable. If you’ re not allowed to use Linux yet, write your applications with Qt, and once all OS related dependencies are removed, switch to your favorite OS without even letting your boss know wink.

See WikiPedia for details about Qt.

Choosing graphical libraries for embedded systems

The free software community offers many solutions to embedded system developers willing to add graphical applications to their project. This variety of choice, typical from the free software world, has the advantage of giving several solutions, which increases the chance of finding the solution that bests suits your need, but at the same time, might confuse to choose the right one.

I made experiments with the major graphical libraries available, and reported these experiments during the Embedded Linux Conference Europe event, which took place early November 2008 in Ede, The Nederland. My presentation « Choosing graphical libraries for embedded systems » discussed DirectFB, X.org and its Kdrive variant, SDL, Nano-X, Gtk, Qt, FLTK and WxEmbedded, detailing the features, specifities, size of each solution and suitability to various use cases.

The slides are available under the Creative Commons BY-SA license : graphical-libraries.pdf (PDF), graphical-libraries.odp (Open Document Format).

While experimenting with these graphical libraries, I made a few contributions to the Buildroot project, which was used to build root filesystems including these libraries. I hope to release soon several root filesystems allowing an easy testing of these solutions, through Qemu.