All Qt developers should know about signals, slots, and properties. Those of you who have used QML will know that property bindings are super useful and cool. Bindings allow us to write more reactive and declarative style code. However, they are only available within QML, which means there are no compile time errors when you […]

In a well-designed QML application, the UI is built using re-usable components, while the data and logic live in C++ based components we call controllers here. The QML part of the application uses these components (that themselves may be written in QML or C++) to build up the user interface and connect these components with […]

Another day, another small addition to KDToolBox, KDAB's collection of miscellaneous useful C++ classes and stuff. In this post, we're going to talk about KDFunctionalSortFilterProxyModel, which is a convenience subclass of QSortFilterProxyModel. What's a proxy model to begin with, and what's QSortFilterProxyModel? Well, that explanation requires a bigger space than what I have in this […]

We just released KDDockWidgets 1.5.0! What is KDDockWidgets? KDDockWidgets is a development framework for custom-tailored docking systems in Qt, to use when you need advanced docking that is not supported by QDockWidgets. It was created by Sergio Martins as a time-saving alternative to QDockWidgets. The ease-of-use of KDDockWidgets can save you lots of frustration as […]

CMake is increasingly becoming the de-facto build system for C++ projects. While it has been possible to build Qt applications using CMake for a long time, with Qt6, Qt switched its own internal build system to CMake. The KDE Community was among the first large, open-source projects that adopted CMake about 15 years ago. Over […]

Once again, the theme of the day is how to speed up Qt development with Visual Studio Code. In part 2 of this blog series, we walked through how to get a complete setup for your qmake and CMake projects, with a deeper look at the Qt side. This time, I will share a few […]

These are some really cool or obfuscated code snippets for your amusement. We didn't want to rate them, so the order doesn't mean anything at all :) Just to make sure that there's no misunderstanding: This code really is/was in the Qt or KDE repositories. From Kivio, main.cpp From Qt 2.2.1 (src/canvas/qcanvas.cpp) Writing code that […]

If you ever need to create a project around a single C++ file (or just a few C++ files) in CMake, as you might for quick test cases, you might find it tedious to write a CMakeLists.txt file by hand every time. To make this easier, I've written a script called cmake-project that you can […]

In 2019, I optimized QStringList::removeDuplicates() by using std::pmp::unordered_set with a std::pmr::monotonic_buffer_resource, when available. The class that I wrote to encapsulate this optimization has since been re-implemented three times. The latest iteration has recently landed in KDToolBox. If you have code that looks a bit like this: then you should read on. Before my change, the […]

As described in our previous blog posts, you can use Visual Studio Code as an IDE for C++ projects. It works particularly well with CMake-based projects. Unfortunately, with build systems not supported natively by VS Code, you need to manually configure include paths and compilation definitions, for the code model to work properly. Since the […]

KDSoap 2.0.0 was just released! What is KDSoap? KDSoap is a tool for creating client applications for web services, without the need for any further component such as a dedicated web server. This tool makes it possible to interact with applications which have APIs that can be exported as SOAP objects. The web service then […]

(Apologies for the clickbait in the post title! But I'd really like people who are searching for solutions to read this.) Between Qt 5.14 and Qt 5.15, my colleague, Marc Mutz, and I submitted a series of patches to Qt that added "range constructors" to the Qt containers. This brought Qt containers one step closer […]

After many struggles with using git LFS on repositories that need to store big files, I decided to spend some time on checking the status of the built-in partial clone functionality that could possibly let you achieve the same (as of git 2.30). TL;DR: The building blocks are there, but server-side support is spotty and […]

In the previous blog post of this series, we discussed KDToolBox::QtHasher, a helper class that allows us to use unordered associative containers datatypes which have a qHash() overload but not a std::hash specialization. The majority of Qt value classes indeed are lacking such a specialization, even if they do provide a qHash() overload. For our […]

Note: This is the English translation of the article first published in German Intro The ESE Congress is one of the lead events for Embedded Software Engineering in Germany. This year it was held digitally for the first time, so that participation was also possible via video. Over five days, there were 3 keynotes and […]

Another day, another blog post about KDToolBox, KDAB's collection of miscellaneous useful C++ classes and stuff. Today, we'll talk about ways to throttle your signal/slots connections -- in other words, how to activate a slot less often than the emission rate of the signal it's connected to. The usual reason why you may want something […]

In the previous blog post about qHash, we explained: how to declare an overload of qHash for your own datatypes, how to hash Qt datatypes for which Qt does not provide a qHash overload, and why you can't use a type from the Standard Library (or just another library) as a key in QHash (newsflash: […]

Einleitung Der ESE Kongress ist die Leitveranstaltung für Embedded Software Engineering in Deutschland. In diesem Jahr fand er erstmals digital statt, so dass die Teilnahme auch per Video möglich war. An fünf Tagen gab es 3 Keynotes und 96 Fachvorträge aus allen Bereichen der Embedded Softwareentwicklung. Anton Kreuzkamp von KDAB sprach über maßgeschneidertes Code-Refactoring mit […]

Another day, another blog about some of KDAB's utility classes. Now it's the turn of KDSingleApplication, a class that helps implement applications that follow the single-instance policy. What is a single-instance policy? Single-instance policy refers to those applications that want to spawn a unique instance for a given user session. Even when launched multiple times, […]

CMake 3.19 was officially released a couple of months ago, and one of the biggest – and most exciting – new features is the addition of presets. What are presets, you might ask, and why should we be excited about them? Presets are a bunch of pre-set CMake options that enable developers to ensure that […]