Book Image

Hands-On Mobile and Embedded Development with Qt 5

By : Lorn Potter
Book Image

Hands-On Mobile and Embedded Development with Qt 5

By: Lorn Potter

Overview of this book

Qt is a world-class framework, helping you to develop rich graphical user interfaces (GUIs) and multi-platform applications that run on all major desktop platforms and most mobile or embedded platforms. The framework helps you connect the dots across platforms and between online and physical experience. This book will help you leverage the fully-featured Qt framework and its modular cross-platform library classes and intuitive APIs to develop applications for mobile, IoT, and industrial embedded systems. Considerations such as screen size, device orientation changes, and small memory will be discussed. We will focus on various core aspects of embedded and mobile systems, such as connectivity, networking, and sensors; there is no IoT without sensors. You will learn how to quickly design a flexible, fast, and responsive UI that looks great. Going further, you will implement different elements in a matter of minutes and synchronize the UI elements with the 3D assets with high precision. You will learn how to create high-performance embedded systems with 3D/2D user interfaces, and deploy and test on your target hardware. The book will explore several new features, including Qt for WebAssembly. At the end of this book, you will learn about creating a full software stack for embedded Linux systems using Yocto and Boot to Qt for Device Creation.
Table of Contents (23 chapters)
Title Page
Dedication
About Packt
Foreword
Contributors
Preface
Index

WebSockets – Bi-directional web communication


Now we are starting to get into the realm of network and the internet. WebSockets are a protocol that allows two-way data exchange between a web browser or client and a server without polling. You can stream data or send data at any time. Qt has support for WebSockets through the use of the QWebSocket API. Like normal TCP sockets, QWebSockets needs a server.

QWebSocketServer

QWebSocketServer can work in two modes: non-secure and SSL. We start by addingwebsockets to the .pro file so qmake sets up the proper library and header paths:

QT += websockets

Then include the QWebSocketServer header file:

#include<QtWebSockets/QWebSocketServer>

The source code can be found on the Git repository under the Chapter07-3 directory, in the cp7 branch.

To create a QWebSocketServer, it takes a server name as a string, a mode, and a parent object. The mode can be SecureMode or NonSecureMode.

SecureMode is is like HTTPS, uses SSL, and the protocol is wss. NonSecureMode...