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Débogage et profilage d’applications Qt sous Linux

La formation “Débogage et profilage d’applications Qt sous Linux” enseigne les techniques de débogage et profilage d’applications sous Linux.

Elle est en particulier (mais pas seulement) appropriée pour les applications utilisant la technologie objet Qt/C++.

A l’issue de la formation, les participants seront capables d’appliquer leur nouveau savoir-faire pour la recherche et la résolution de problèmes dans leurs applications Qt sous Linux, qu’il s’agisse de dysfonctionnements ou de problèmes de performance.

Prérequis

Une expérience professionnelle de la programmation en Qt …

Hotspot v1.1.0 adds timeline and recording features New release of the GUI for the Linux perf profiler

Close to three months after the initial hotspot release, I’m happy to announce the release of version 1.1.0. Quick recap: Hotspot is a graphical frontend to the Linux perf profiler suite. It allows you to visually analyze perf.data files with the built-in Flame Graph and the Bottom-Up, Top-Down, or Caller-Callee data tables. It is a free open source R&D project by KDAB, you can find the code on GitHub.

Version 1.1.0 adds two important new features to this …

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 …

Slaying Latency with Linux Kernel Tracepoints

Knowing what tools are at your disposal when looking to make a program faster or keep it operating smoothly is critical to your success as a programmer. We recently solved a performance problem using Linux Kernel Tracepoints so we thought we’d share the process with you so that you can see for yourself if this tool makes sense in your toolkit.

Our challenge: the database writes in a customer’s application normally took under 5ms but occasionally spiked to over 150ms, …

Faster than Fast String Search in Qt

Is your code burning a lot of cycles hunting for strings? Maybe you need to find the proper charset nestled in a chunk of HTML, or look for the dimensions in an XPM image file, or locate the email attachment boundaries in a block of MIME. If you string search a lot and performance is important to you, you’ll want to keep reading!

You may have encountered Boyer-Moore string searches if you have a formal education in Computer Science or …

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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