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
Credits
About the Authors
About the Reviewers
www.PacktPub.com
Preface
Index

Time for action – reacting to an item's selection state


The assigned pointer to a QStyleOptionGraphicsItem item might become handy if you want to alter the appearance of the item related to its state. For example, say you want to fill the rectangle with red when it gets selected. To do so, you only have to type this:

void paint(QPainter *painter, const QStyleOptionGraphicsItem *option, QWidget *widget) {
  Q_UNUSED(widget)
  if (option->state & QStyle::State_Selected)
    painter->fillRect(boundingRect(), Qt::red);
  else
    painter->fillRect(boundingRect(), Qt::black);
}

What just happened?

The state variable is a bitmask holding the possible states of the item. You can check its value against the values of the QStyle::StateFlag parameter by using bitwise operators. In the preceding case, the state variable is checked against the State_Selected parameter. If this flag is set, the rectangle is painted red.

Tip

The type of state is QFlags<StateFlag>. So, instead of using...