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Getting the most of signal/slot connections
Posted In: Qt
Signals and slots were one of the distinguishing features that made Qt an exciting and innovative tool back in time.
Read MoreCreating Custom Widgets
Creating custom widget is not a hard problem, but there are a few things you should consider. This is meant as a check-list you can go to, when you create a new widget. Just run through the list and you are well on your way to creating a good widget that will serve you well in many different circumstances.
Read MoreQtQuick Custom Item Performance
One can read here and there that OpenGL is the fastest. QQuickPaintedItem is slow. And Canvas is really slow. But I couldn't find any information on how fast or slow each solution is. So I decided to do a quick comparison, to get an idea of their performances. So I did a quick and simple rendering of many rectangles using each technology. And measured the frames per second.
Read MoreKeyboard navigation and the event system
Posted In: Qt
Keyboard navigation in a GUI application might not be the most highlighted feature. Most devices use clickable or touchable controls in the user interface to change screens, open menus or activate buttons. Many developers don't even bother looking at the problem because the customers might not ask for it. But if said application is intended for a device that doesn't have other kind of input, or you have to satisfy some accessibility requirements, it's definitely something that will end up being the feature that blocks a release if it has some known bug. First we will cover some interesting details of Qt's event system, and then we will move to the details that you should know for providing your UI with a good keyboard navigation system.
Read MoreHow to use QThread properly
Posted In: Qt
There are basically two different ways of using QThread directly: Worker threads or subclassing. Those two are confusing to a lot of developers, and I will try to explain when you should use those. I will also explain how signals and slots work with threads and how they can help you or lead to problems.
Read MoreSerializing/deserializing a QObject tree
A while ago I wanted to implement save and load for an application. The application model was a QObject derived class, with a bunch of sub (-sub) classes. As the UI was QML, everything was accessible through properties. Instead of writing a save and load mechanism for every single class, I was able to write one generic save load mechanism. This can be done using QObject introspection/reflection. So the class name, properties and member functions can be queried.
Read MoreXml/Json Comparison
Recently I needed to implement a client application that would fetch data from a web service. The client had to be written in C++ using the Qt 5.4 libraries, the server was already running Apache2 with php 5.something but the …
Read MoreBuilding Qt 5.4 on Windows
In this blog post I will go through the process of building a 32 bit Qt 5.4 with OpenSSL support on Windows. I will use Windows 8.1 64 bit and Visual Studio 2013, but there should only be minor things …
Read MoreQWidget Pixel Drawing
Posted In: Qt, Qt Tricks, Widgets
In very rare occasions, we want to draw individual pixels all over a widget. Custom painted widgets are much less common. But we can often get away with much easier painting than doing individual pixels. We draw these using lines, …
Read MoreEncapsulation in QML Components
Posted In: QML
In QML, it’s so easy to use properties of components directly, and it’s even the way most examples do it. But here’s my quesion: If we consider this the wrong approach in C++, isn’t it wrong in QML as well? …
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