QZXing is a very useful library: It provides an easy to use Qt integration API around the barcode scanning library ZXing (zebras crossing). Because it is so easy to setup QZXing in a Qt application, we and most of our customers end up using it when they need to scan images for barcodes. There is, […]

In a previous blog post we introduced clazy, a clang plugin which makes the compiler understand Qt semantics, allowing you to get compile-time warnings about Qt best practices ranging from unneeded memory allocations to misuse of API, including fix-its for automatic refactoring. Today we'll do a round-up and present the checks related to connect statements, […]

As an Easter treat here is a quick taster of some of the animation goodies coming to Qt 3D along with Qt 5.9. In this post we will briefly outline the steps needed to create a simple Qt 3D application and the assets it uses to produce this little animation: The basic steps are: Create […]

A small new feature that I have added to Qt 5.8 is the possibility of disabling narrowing conversions in the new-style QObject::connect statement. In this short blog post I would like to share with you why I thought this was useful and therefore implemented it. The problem Since Qt 5.0, the new-style, PMF-based (pointer to […]

After two months of intensive reviews, discussions, fixes, and stripping down the initial commit, feature by feature, to make it acceptable, I am happy to announce that the first QStringView commits have landed in what will eventually become Qt 5.10. Even the docs are already on-line. This is a good time to briefly recapitulate what […]

All Qt developers have asked themselves at least once in their careers: "why isn't my slot invoked?" (I've asked myself that question many, many times). There are a number of reasons why a connection may fail to be properly set up, and ultimately cause our slot not to be invoked. This blog post is a […]

A small new feature that was added to Qt 5.8 is the ability for moc (Qt's meta-object compiler) to extract meta-object information at the namespace level. This means, for instance, that you can have introspection support for enumerations defined in a namespace (not just in QObject subclasses, or classes tagged with Q_GADGET), and use such […]

I'm extremely happy to finally announce the first stable release of heaptrack, the FOSS heap memory profiler for C/C++ Linux applications. You can download the source tarball from the KDE mirrors: https://download.kde.org/stable/heaptrack/1.0.0/src/ Heaptrack is a fast heap memory profiler that runs on Linux. It allows you to track all heap memory allocations at run-time. Afterwards, […]

Qt 5.8 has just been released! Another great release of Qt, made possible by thousands of commits by over a hundred different contributors: And here we are again, with the usual showcase of the most outstanding contributions to Qt 5.8 developed by KDAB engineers. In no particular order: Qt 3D Qt 3D continues to receive […]

We have released version 2.7 of our Qt application introspection tool GammaRay. GammaRay allows you to observe the behavior and data structures of Qt code inside your program live at runtime. Here are a few of the highlights of this release: The new Qt 3D geometry inspector allows you to look at a wireframe rendering […]

This is the first in a series of blog posts on QStringView, the std::u16string_view equivalent for Qt. You can read about QStringView in my original post to the Qt development mailing-list, follow its status by tracking the "qstringview" topic on Gerrit and learn about string views in general in Marshall Clow's CppCon 2015 talk, aptly […]

In the last days, I was once again trying to convince fellow programmers that there's no such thing as a "benign" data race. This is a recurring theme, in particular fueled by the docs of MSVC and Intel x86, which basically seem to say "you don't need atomics here". I perused the excellent papers Benign […]

The last post from my colleague Marc Mutz about deprecating Q_FOREACH caused quite an uproar amongst the Qt developers who follow this blog. I personally feel that this was caused fundamentally by a perceived threat: there is a cost associated to porting away a codebase from a well-known construct (Q_FOREACH) to a new and yet-undiscovered […]

Android Things is Google’s answer to creating an environment for IoT devices. Take a slimmed down Android build, add some sensor-specific APIs, and provide it on a number of powerful pre-integrated micro-boards and you have a ready-made platform for building a host of upcoming IoT devices. Android Things can take advantage of many existing Android […]

On December 1st, KDAB’s Kévin Ottens and David Faure co-hosted a one day Meet Qt in Lyons, with The Qt Company and Witekio. The event was booked out with 50 people attending, confirming the growing community of Qt users in France. Participants were given plenty of opportunities for questions throughout the day and much appreciated […]

Functional Safety is the term used for systems designed to minimize risk to human health. But there’s a dilemma in today’s tech-driven world. We are more reliant than ever on software to control our planes, trains, cars, and boats, to operate our medical equipment, to process our food, to clean our water, and to power […]

For today's blog I would like to share with you the little adventure I had when fixing a very strange bug in Qt. Pop quiz Don't think about this too much, just guess: what does this QML snippet print? There are no JavaScript semantic tricks involved; and using either == or === does not change […]

GammaRay is a high-level runtime introspection tool for Qt applications. In this talk we will look at a number of real-world debugging and profiling problems and how the capabilities provided by GammaRay help you with those. When creating applications we strive to use higher-level frameworks to obtain results quickly and reduce development effort and long-term […]

This talk introduces you to the fundamentals of threading in Qt. We will discuss how threads, QObjects and events interact together; how a thread affinity of a QObject has a play in signals and slots connections; and how you can leverage the modern C++11 threading capabilities in your Qt application. Cross-platform thread support was introduced […]