Book Image

Game Programming Using Qt: Beginner's Guide

By : Lorenz Haas, Witold Wysota, Witold Wysota, Lorenz Haas
Book Image

Game Programming Using Qt: Beginner's Guide

By: Lorenz Haas, Witold Wysota, Witold Wysota, Lorenz Haas

Overview of this book

Qt is the leading cross-platform toolkit for all significant desktop, mobile, and embedded platforms and is becoming more popular by the day, especially on mobile and embedded devices. Despite its simplicity, it's a powerful tool that perfectly fits game developers’ needs. Using Qt and Qt Quick, it is easy to build fun games or shiny user interfaces. You only need to create your game once and deploy it on all major platforms like iOS, Android, and WinRT without changing a single source file. The book begins with a brief introduction to creating an application and preparing a working environment for both desktop and mobile platforms. It then dives deeper into the basics of creating graphical interfaces and Qt core concepts of data processing and display before you try creating a game. As you progress through the chapters, you’ll learn to enrich your games by implementing network connectivity and employing scripting. We then delve into Qt Quick, OpenGL, and various other tools to add game logic, design animation, add game physics, and build astonishing UI for the games. Towards the final chapters, you’ll learn to exploit mobile device features such as accelerators and sensors to build engaging user experiences. If you are planning to learn about Qt and its associated toolsets to build apps and games, this book is a must have.
Table of Contents (18 chapters)
Game Programming Using Qt
About the Authors
About the Reviewers

Time for action – displaying a proper error message

Fortunately, QNetworkReply offers several possibilities to do this. In the slot called downloadFinished(), we first want to check whether an error occurred:

if (reply->error() != QNetworkReply::NoError) {/* error occurred */}

The QNetworkReply::error() function returns the error that occurred while handling the request. The error is encoded as a value of the QNetworkReply::NetworkError type. The two most common errors are probably these:

Error code



This error indicates that the URL of the request could not be found. It is similar to the HTTP error code 404.


This error indicates that you do not have the permission to access the requested file. It is similar to the HTTP error code 401.

You can look up the other 23 error codes in the documentation. But normally, you do not need to know exactly what went wrong. You only need to know whether everything worked out—QNetworkReply::NoError...