Qt 4.3编程指南：C++ GUI实战

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"C++ GUI编程与Qt 4（第2版）" 《C++ GUI Programming with Qt 4 (2nd Edition)》是由Jasmin Blanchette和Mark Summerfield合著的一本关于使用Qt 4.3进行图形用户界面编程的专业书籍，由Prentice Hall出版社于2008年2月4日出版。该书的印刷版ISBN-10为0-13-235416-0，ISBN-13为978-0-13-235416-5，电子版ISBN-10为0-13-714397-4，ISBN-13为978-0-13-714397-9，总共有752页。书中包含了详细的目录和索引，为读者提供了全面的学习路径。这本书是Qt 4.3编程的官方最佳实践指南，特别强调了在Windows、Linux/Unix、Mac OS X以及嵌入式Linux平台上无需源代码更改即可本地运行的工业级C++应用程序的开发。作者Jasmin Blanchette和Mark Summerfield都是Trolltech公司的内部专家，他们将自己丰富的经验融入书中，帮助读者掌握Qt 4.3的最新功能和最佳实践。书中涵盖了从实现模型/视图架构到利用Qt 4.3增强的图形支持的各种主题。对于几乎每一个GUI开发任务，作者都提供了经过验证的解决方案。此外，还深入探讨了提供数据库访问、集成XML以及使用子类化等高级技术。这使得开发者能够构建功能强大且跨平台的应用程序。本书的特点包括： 1. **Qt 4.3介绍**：详细介绍了Qt 4.3的新特性，包括改进的图形系统和API更新。 2. **模型/视图编程**：阐述了如何利用Qt的模型/视图架构来构建可扩展和灵活的用户界面。 3. **图形支持**：探讨了Qt 4.3中的图形系统，包括QGraphicsView和QGraphicsWidget，以及如何创建复杂的动画效果。 4. **数据库集成**：提供了与各种数据库系统交互的策略，如SQLite、MySQL等。 5. **XML支持**：讲解了如何在Qt应用程序中读写XML文件，以及利用Qt的XML模块进行数据存储和交换。 6. **事件处理和信号/槽机制**：解释了如何有效地处理用户输入和系统事件，以及使用信号和槽进行组件间的通信。 7. **国际化和本地化**：介绍了如何使应用程序适应不同语言和地区。 8. **性能优化**：提供了关于提高Qt应用程序性能的技巧和最佳实践。 9. **调试和测试**：讨论了调试Qt应用程序的方法，以及如何进行单元测试和集成测试。《C++ GUI Programming with Qt 4 (2nd Edition)》是一本全面而深入的教程，适合想要学习或提升Qt 4.3编程技能的C++开发者。无论你是初学者还是有经验的程序员，都能从中受益匪浅，掌握构建高效、跨平台的GUI应用的关键技术和方法。

6 QLabel *label = new QLabel("Hello Qt!");

7 label->show();

8 return app.exec();

9 }

Lines 1 and 2 include the definitions of the QApplication and QLabel classes. For every Qt class, there is a

header file with the same name (and capitalization) as the class that contains the class's definition.

Line 5 creates a QApplication object to manage application-wide resources. The QApplication constructor

requires argc and argv because Qt supports a few command-line arguments of its own.

Line 6 creates a QLabel widget that displays "Hello Qt!". In Qt and Unix terminology, a widget is a visual

element in a user interface. The term stems from "window gadget" and is the equivalent of both "control" and

"container" in Windows terminology. Buttons, menus, scroll bars, and frames are all examples of widgets.

Widgets can contain other widgets; for example, an application window is usually a widget that contains a

QMenuBar, a few QToolBars, a QStatusBar, and some other widgets. Most applications use a QMainWindow or

a QDialog as the application window, but Qt is so flexible that any widget can be a window. In this example,

the QLabel widget is the application window.

Line 7 makes the label visible. Widgets are always created hidden so that we can customize them before

showing them, thereby avoiding flicker.

Line 8 passes control of the application on to Qt. At this point, the program enters the event loop. This is a

kind of stand-by mode where the program waits for user actions such as mouse clicks and key presses. User

actions generate events (also called "messages") to which the program can respond, usually by executing one

or more functions. For example, when the user clicks a widget, a "mouse press" and a "mouse release" event

are generated. In this respect, GUI applications differ drastically from conventional batch programs, which

typically process input, produce results, and terminate without human intervention.

For simplicity, we don't bother calling delete on the QLabel object at the end of the main() function. This

memory leak is harmless in such a small program, since the memory will be reclaimed by the operating system

when the program terminates.

It is now possible to try the program on your own machine. It should look like the one shown in Figure 1.1.

First, you will need to install Qt 4.3.2 (or a later Qt 4 release), a process that is explained in Appendix A. From

now on, we will assume that you have a correctly installed copy of Qt 4 and that Qt's bin directory is in your

PATH environment variable. (On Windows, this is done automatically by the Qt installation program.) You will

also need the program's code in a file called hello.cpp in a directory called hello. You can type in hello.cpp

yourself or copy it from the examples that accompany this book, where it is available as

examples/chap01/hello/hello.cpp. (All the examples are available from the book's web site,

http://www.informit.com/title/0132354160.)

Figure 1.1. Hello on Linux

From a command prompt, change the directory to hello, and type

qmake -project