Book Image

Mastering Qt 5 - Second Edition

By : Guillaume Lazar, Robin Penea
Book Image

Mastering Qt 5 - Second Edition

By: Guillaume Lazar, Robin Penea

Overview of this book

Qt 5.11 is an app development framework that provides a great user experience and develops full capability applications with Qt Widgets, QML, and even Qt 3D. Whether you're building GUI prototypes or fully-fledged cross-platform GUI applications with a native look and feel, Mastering Qt 5 is your fastest, easiest, and most powerful solution. This book addresses various challenges and teaches you to successfully develop cross-platform applications using the Qt framework, with the help of well-organized projects. Working through this book, you will gain a better understanding of the Qt framework, as well as the tools required to resolve serious issues, such as linking, debugging, and multithreading. You'll start off your journey by discovering the new Qt 5.11 features, soon followed by exploring different platforms and learning to tame them. In addition to this, you'll interact with a gamepad using Qt Gamepad. Each chapter is a logical step for you to complete in order to master Qt. By the end of this book, you'll have created an application that has been tested and is ready to be shipped.
Table of Contents (16 chapters)

Flying over Qt multithreading technologies

Built upon QThread, several threading technologies are available in Qt. First, to synchronize threads, the usual approach is to use a mutual exclusion (mutex) that will apply for a given resource. Qt provides it by means of the QMutex class. Its usage is straightforward:

QMutex mutex; 
int number = 1; 
 
mutex.lock(); 
number *= 2; 
mutex.unlock(); 

From the mutex.lock() instruction, any other thread trying to lock mutex will wait until mutex.unlock() has been called.

The locking/unlocking mechanism is error-prone in complex code. You can easily forget to unlock a mutex in a specific exit condition, causing a deadlock. To simplify this situation, Qt provides QMutexLocker, which should be used where QMutex needs to be locked:

QMutex mutex; 
QMutexLocker locker(&mutex); 
 
int number = 1; 
number *= 2; 
if (overlyComplicatedCondition...