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07.08.2017 No comments

New in Qt 5.10: Diagnostics when breaking QML bindings

Property bindings are one of the most interesting features of the QML language. In QML, when we set a value on a property, the right hand side expression isn’t evaluated just once to produce a value, like in a ordinary imperative language.

In particular, if the expression involves other properties, then the property we’re setting becomes bound to the properties in the expression: whenever they change their values, then the expression is automatically evaluated again, and the target property value …

20.06.2017 No comments

A tale of 2 curves Or the complexity simplicity requires.

As my first subject for this animation blog series, we will be taking a look at Animation curves.

Curves, or better, easing curves, is one of the first concepts we are exposed to when dealing with the subject of animation in the QML space.

What are they?

Well, in simplistic terms, they are a description of an X position over a Time axis that starts in (0 , 0) and ends in (1 , 1). These curves are …

12.06.2017 No comments

GammaRay 2.8.0 Release

We have released version 2.8.0 of our Qt application introspection tool GammaRay. GammaRay allows you to observe behavior and data structures of Qt code inside your program live at runtime.

A big focus in this release is improvements to the Qt Quick inspector, which gained layout helper grids and Qt Quick Controls 2 tracing, as well as initial support for the software renderer. We have also optimized the performance of the remote view, which previously managed to saturate a …

31.05.2017 No comments

KDAB contributions to Qt 5.9

Qt 5.9 has just been released!

This release marks two important milestones for the Qt Project. The first is that now the Qt 5 series has had more releases than any other Qt version ever (the last release of the Qt 4 series was Qt 4.8). The second milestone is that Qt 5.9 will be a Long Term Support release, therefore providing to many users a stable foundation to build their applications upon.

KDAB has been a significant contributor to …

10.05.2017 No comments

Corso di Qt/QML per Embedded a Milano, settembre 2017

KDAB è lieta di annunciare una data italiana per il corso Programmazione Qt/QML per sistemi embedded, che si svolgerà a Milano dal 12 al 14 settembre 2017.

Qt è un application framework moderno e ricco di funzionalità, utilizzato per realizzare applicazioni cross-platform per sistemi embedded, mobile e desktop. Qt è usato da oltre 800.000 sviluppatori in tutto il mondo per creare interfacce di domotica e home automation; sistemi di in-vehicle infotainment (IVI); pannelli di controllo industriale; applicazioni desktop …

24.04.2017 2 comments

Efficient barcode scanning with QZXing Profiling Qt Zebras Crossing

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, or rather was, a big problem though: When you want to analyze a live camera video stream, e.g. from a phone camera, the latency can …

28.02.2017 No comments

KDAB contributions to Qt 5.8

Qt 5.8 has just been released! Another great release of Qt, made possible by thousands of commits by over a hundred different contributors:

Commit percentages to Qt in the last 16 weeks, grouped by employer

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 lots of improvements and bugfixes, thanks to the hard work of …

28.02.2017 No comments

GammaRay 2.7.0 Released

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 of entity geometries, as well as the raw OpenGL buffer data. Visualizations of normal vectors and backface culling help to identify common problems in geometry
…

23.02.2017 No comments

Integrating OpenGL with Qt Quick 2 applications (part 2)

In the last blog post we gave a very high level introduction to the Qt Quick 2 renderer. We also showed how various signals are emitted by the renderer during the synchronization and rendering steps. In this blog post we’re going to discuss those signals and show how they can be used to implement overlays and underlays.

Signals emitted by the Qt Quick renderer

Let’s start again by looking at this diagram of the synchronization between the render thread of …

21.12.2016 No comments

Fixing bugs via lateral thinking

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?

import QtQuick 2.0

QtObject {
    Component.onCompleted: {
        console.log("240000000000" == "3776798720");
    }
}

There are no JavaScript semantic tricks involved; and using either == or === does not change the result in any way.

Did you get it?

Pop quiz (2)

Here’s …

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