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Lots of lights: Generating cities Data visualization with Qt 3D, OpenGL and C++

Sometimes data visualization might call for more than a graph – you need to visualize complex data, such as that generated by city lighting, in three dimensions to get the full effect.

KDAB decided to put together a showcase for the Qt World Summit that allowed us to demonstrate Qt 3D’s capabilities as a performant next-generation graphics engine, which can draw thousands of lights and objects simultaneously. This also enabled us to show what modern technologies like Qt 3D can …

Clang Tidy, part 2: Integrate qmake and other build systems using Bear Automated refactoring of your source code using powerful open-source tooling

Introduction

This article is part of a blog series about Clang Tidy. In the previous article we learned about the general usage of Clang Tidy to automatically refactor source code…

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 …

Writing Code That Won’t Kill A Functional Safety Source Book

Functional Safety is the term used for systems designed to minimize risk to human health. But there’s a dilemma in today’s tech-driven world.

We are more reliant than ever on software to control our planes, trains, cars, and boats, to operate our medical equipment, to process our food, to clean our water, and to power our homes. If these systems don’t function properly, they have the ability to injure, or even kill us. Meanwhile software complexity continues to increase exponentially …

Qt on Android: How to create an Android service using Qt

Starting with Qt 5.7, we added the ability to create Android services using Qt. In this article we’re going to see how to get started and also how to communicate between the two.

Before we get started I want to add a big bold WARNING about the performance! Because the services are run in the background for a very long time, make sure your service doesn’t drain the device battery!

Getting started

Step I: Extend QtService

Every single Qt Android …

Qt on Android: How to restart your application

Some time ago, I wrote a code to restart the running application on Android.

You might well ask why such a thing was needed. It was needed because there are cases where, whenever a user changes the theme, the application has to restart to apply the change (it can’t be applied on the fly). In my example I used it to restart Qt Quick Controls 2 gallery.

Sadly my fix was not accepted, because other platforms (iOS, IIRC) have this …

Qt on Android: How to use Android Toast

To get you started on this, we’ll be using KDAB’s Android utils with the humble Toast. Toasts are small popups which are used to show the user some feedback. Check Google’s API guide for more info about toasts.

The easiest way to show a toast is to use Toast.makeText(Context context, CharSequence text, int duration) static method. This method needs 3 params:

  • the context (we’ll use the activity)
  • the text to show
  • and the duration: one of LENGTH_SHORT (0) and

Qt on Android: How to convert Qt images to Android Images and vice-versa

Sometimes we need to exchange images from Android world to Qt world and vice-versa, therefore in this article we’re going to see how to convert a QImage to an Android Bitmap and how to convert an Android bitmap and an Android Drawable into a QImage.

To get access to Android Bitmap data & info we’re going to use NDK’s support, so we need to make sure jnigraphics library is in libraries dependency in our .pro file:

LIBS += -ljnigraphics

Now …

Embedding QML: Why, Where, and How

If you’re already using QML in Qt, you know that it can help quickly create flexible user interfaces using little or no C++ programming. With a basic text file and some JavaScript logic, you can put together a pretty sophisticated interface like that shown in the Qt Quick Clock demo (below) with a minimum of fuss. But did you know you can compress your plainly readable QML and hide it away inside a binary?

 

Figure 1: Qt Quick Clock

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