Some time ago, I wrote a post about integrating Qt's associative containers with the fancy new C++ features, range-based for loops with structured bindings. That post inspired KDAB's own Giuseppe D'Angelo to add the asKeyValueRange member function to both QHash and QMap. Now it's possible to iterate over them with a simple range-based for loop, […]

You have two choices when it comes to giving a custom style to your Qt widgets. Qt Style Sheets are very convenient for getting started -- just a few CSS-like rules, and they work. It is our experience, however, that Qt Style Sheets create too much trouble and a QStyle subclass (*) gives a better […]

The nlohmann/json library is everything a developer can expect from a modern library -- easy to integrate and JSON objects are treated as first class citizens with a very intuitive API. However, it has one problem that is widely mentioned across the internet, which I'll tell you about below. Various solutions to the problem have […]

C++23 is feature complete and on track to be released next year. While many people are complaining that it's, after all, a "minor" release (as the pandemic made the Committee work very difficult), C++23 still has a few very significant changes. In this blog post, I want to talk about what I think is my […]

Qt is a high quality library, but it is also massive in number of features. This massive number results in a higher likelihood that there are bugs that go unnoticed lying around in its less frequently used features or combination of features. Our friends at qgis.org hired us to solve some of those issues that […]

At KDAB, we have been investigating how to integrate Rust with Qt in a safe and idiomatic way. The solution we are currently working on is called CXX-Qt. It's available in the GitHub and on crates.io. This blog post discusses the journey of CXX-Qt -- where it started, where it can be used right now, […]

A couple of weeks ago, we guided you through setting up a chat application and server in our first blog of this series. This is the second and final blog of this Qt Allstack series. Firebase Messaging Now that we have a functional chat application, it’s time to add real world features, like push notifications. […]

Writing mobile apps can be a lot of fun, especially with Qt and QML. But if your background is all about C++ and Qt, writing the entire required stack for a mobile app can be challenging. Adding push notifications, storing information, and having to write that with another language and framework might make you give […]

Here at KDAB, we recently published a library called KDBindings, which aims to reimplement both Qt signals and slots and data binding in pure C++17. To get an introduction to the KDBindings implementation of signals and slots, I recommend that you take a look at the KDBindings Getting Started Guide. It will give you an […]

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 […]

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 […]

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 […]

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 […]

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 […]