Programming with Qt, 2nd Edition

Chapter 1. Introduction

Qt is a C++ class library and GUI toolkit for Unix, Windows, and embedded systems (with the latter running on Linux). In this chapter, we will introduce GUI programming in general and Qt programming in particular. We tell you why you need a GUI toolkit and why Qt is a good choice for such a toolkit. You can check Section 1.7 to make sure you know enough about C++. This chapter also tells you where you can turn if you have any problems with Qt.

Why GUI Toolkits?

GUI toolkits are not well known in the MS Windows or Macintosh world, but they are ubiquitous on Unix. This is because the Windows GUI programming API and Macintosh programming tools already contain high-level features such as buttons, scrollbars, and functions for manipulating colors, fonts, and other visual flourishes. On Unix systems, things are different. The pre-eminent windowing system on Unix—the X Window System—is very flexible, but it does not offer the programmer much help. About the only thing you get are functions that help you draw primitive graphics like lines and rectangles, set the foreground and background color, and have user interactions and other events reported back to you. These functions are network transparent, which is a very good thing, but these limited graphical features are nevertheless difficult to program. There is nothing for creating buttons or scrollbars, let alone more complex items such as dialog boxes, toolbars, or tab pages.

Of course, nobody wants to code ...