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 […]

Version 1.3.0 of the KDE Heaptrack project was just released by KDAB's Milian Wolff. Heaptrack is a heap memory profiler on Linux-based operating systems. It can help you find hotspots that need to be optimized for reducing memory usage, memory leaks, allocation hotspots, and temporary allocations. Included in this release is a special new feature […]

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 […]

GammaRay 2.11.3 has been released! GammaRay is KDAB's software introspection tool for Qt applications. Leveraging the QObject introspection mechanism, it allows you to observe and manipulate your application at runtime. This works both locally on your workstation and remotely on an embedded target. Version 2.11.3 will be the last in the 2.11 series. After this […]

Wayland is a display protocol, a protocol (and accompanying C library) spoken by a graphical application with a display server in order to communicate about both input to the application (keyboard, mouse, ...) and about output from the application -- that is, the rendered window. Wayland was developed to replace the X11 server on the […]

In Qt 5.10, we added support for recursive filtering in QSortFilterProxyModel, which means keeping all parents of items matching the filter. One of the comments in the blog post about that feature was "Sometimes, you do not only want to show parents for a match (so the match is visible), you may (also) want to […]

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 […]

The KDE Community has been developing a variety of Free Software products using Qt for 25 years now. Among them, the Plasma Desktop Environment, creativity tools like Krita and Kdenlive, educational applications like GCompris, groupware suites like Kontact and countless other applications, utilities, and widgets. Qt is famous for its rich set of high-quality, cross-platform […]

Version 2.0.0 of KD Reports has just been released! KD Reports creates all kinds of reports from within Qt applications. These reports are printable and exportable from code and XML descriptions. KD Reports is a developer tool used in source code, but it allows the use of templates that are created by design staff. Reports […]

KDDockWidgets 1.4.0 has been released! KDDockWidgets is a framework for custom-tailored docking systems in Qt. This is a major release with new features and lots of fixes. KDDockWidgets 1.4.0 Overview The big highlights of KDDockWidgets 1.4.0 are the experimental MDI support and the new declarative API for QtQuick: By using MainWindowMDI, you can now have […]

Some time ago, I noticed that a unit test was quite slow, using 100% CPU for a number of seconds at one point in the test. I used perf and KDAB's Hotspot to record and examine where the CPU cycles were spent in that unit test, and I quickly noticed that a lot of time […]

It is our pleasure to introduce a shiny new Maps & Navigation solution for QML developers! This QML plugin is a joint effort between KDAB & General Magic to bring the excellent General Magic Maps and Navigation SDK to the QML world. What makes the General Magic QML plugin special? It's easy to use. With […]

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 […]

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 […]