C++ GUI Programming with Qt 4 148
Ravi writes "When somebody talks about the Qt Framework, the first thing that comes to mind is KDE one of the most popular Desktops which is built using the Qt library. Qt is a C++ GUI framework created by the Norwegian firm Trolltech which can be used to build applications for a variety of OSes and platforms. The latest version of Qt (Ver 4.0) contains huge improvements over its earlier versions such as advanced modal/view functionality, easy to use template containers and better Unicode support just to name a few. I have been excited about the ease with which one can build GUI applications using Qt. Trolltech provides the library in two licences - the free licence which mandates that the applications developed be released under GPL and a commercial non-free licence which allows one to develop closed source applications using Qt." Read the rest of Ravi's review.
| C++ GUI Programming with Qt 4 | |
| author | Jasmin Blanchette and Mark Summerfield |
| pages | 540 |
| publisher | Prentice Hall |
| rating | 9 |
| reviewer | Ravi |
| ISBN | 0-13-187249-4 |
| summary | A great book to learn the latest version of Qt (Ver 4.0) to create applications that run natively in Linux/Unix, Windows and Mac OS X |
I found the latest book on Qt titled "C++ GUI Programming with Qt 4" authored by Jasmin Blanchette and Mark Summerfield and brought out by Prentice Hall to be a remarkable book in that it takes the readers through the basics of creating applications using the latest version of Qt and gradually shifts to explain the more advanced concepts of GUI programming using this C++ framework.
The book, all of 540 pages is divided into three parts - the first part containing 5 chapters dealing with Basic Qt, the second part titled Intermediate Qt which contains 11 chapters and the final part titled Advanced Qt containing an additional 5 chapters.
The major work in picking up skills in a new GUI framework revolves around getting to know all the classes and their member functions. And learning Qt is no different. In the first five chapters (Part I of the book), one gets to know the rudimentary concepts behind creating GUI applications using the Qt toolkit. And remarkably, instead of boring the readers with the different Qt classes, the authors take a hands on approach and introduce the concepts via examples.
In chapters 1 through 5, the readers are introduced to rapid dialog design using the Qt Designer, introduction to the main Qt classes such as QApplication, QObject, QWidget and its child classes as well as a good understanding of the concept of Signals and Slots which form the meat behind communication between different objects in Qt. Apart from that the 5th chapter also introduces to the reader the concept of Double buffering - one which is used popularly by the programmers in eliminating flicker in the GUI interface.
The sixth chapter titled "Layout Management" falls in the second part namely "Intermediate Qt". Here one gets to know and tryout the different layout classes that are available in Qt using which one can easily design sophisticated GUI applications. This chapter also gives the reader an introduction to Multiple Document Interface by way of an example.
Event Processing forms the basis of the seventh chapter where the authors explain how to catch events such as key presses and timers. Apart from that the authors also explain the five levels at which events can be processed and filtered in Qt.
Qt has an excellent collection of classes for creating 2D and 3D graphics. And from version 4, the classes are grouped into modules which need only be plugged in on a need to use basis. The primary class which deals with the 2D graphics engine in Qt is the QPainter class. The use of this class has been explained in detail in the eighth chapter titled "2D and 3D Graphics". Other than that, one also gets to know about the OpenGL module in Qt which makes it very easy to integrate OpenGL code into Qt applications as well as the classes which implement printing.
It is really interesting to see that the entire subject of Qt is apportioned into separate chapters with each chapter dealing with a particular topic. For example, if in the 9th chapter, the authors dwell on explaining the classes which implement drag and drop support, the succeeding chapter elaborates on the Model view controller architecture which forms the basis for most item view classes which implement tables, tree views and lists.
Another thing worth noting is that each chapter is explained with a complete stand alone example which makes it easy to try out what one has learned and also get a better idea of the concepts behind the classes that are explained. So while learning say about the container classes in Qt, the reader can actually try out an example and the code is accompanied by step-by-step explanations which makes it much more simpler to grasp the concepts.
All object oriented languages contain what are known as container classes - those which are responsible for creating sorted and unsorted data arrays, vectors and lists. And C++ has a couple of them in the Standard Template Library (STL). Qt has its own wide array of container classes which sport a number of improvements over STL in that they support implicit sharing (Copy on Write) which gives the applications a significant performance boost. In the 11th chapter titled Container Classes, the authors explain the concept of containers and the Qt classes that can be used for the same.
The next two chapters deal with writing and reading data from files as well as databases. And in each case, the concepts are explained with the aid of examples which makes the narration much more interesting to follow.
Qt has good support for Networking as well as XML which is evident from the 14th and 15th chapters which elaborate on the classes responsible for these. Even though these two short chapters do not cover all the networking or XMl concepts, I found them to impart a good idea of the use of a couple of important Qt classes related to networking and XML.
The 17th chapter titled "Internationalization" falls in the Advanced section of the book. I found this chapter to be an eye opener in that, with Qt's robust use of Unicode, it is possible to create applications which support a wide variety of non-english languages.
But one of the very important concept of multi-threading is explained in the next chapter titled what else "Multithreading" where the authors teach how to create threads easily in Qt.
If one looks at any KDE application, it will be evident how the parent application can be extended by use of plugins. A plugin is a dynamic library which implements a particular interface to provide extra functionality to the user. In the 19th chapter, one gets to know how to create dynamic libraries using Qt which can then be plugged into the parent application.
In the penultimate chapter, the authors explain all the platform specific features and tweaks such as using ActiveX in Windows and handling session management in X11. There are also four pages - which I believe to contain the shortest chapter I have ever come across and where a couple of classes which can be used in programming for embedded devices such as mobile phones are listed. By including this tiny chapter, perhaps, the authors were sending a signal to the developer community that Qt is fully ready for use in embedded development.
From start to finish, I found the book immensely enjoyable. The style of narration of the authors which interleaves the example code with the explanation is ideally suited to pick up skills in using any toolkit without getting bored, especially since the bulk of the learning involves acquiring a fine understanding of the classes the toolkit provides. As a bonus the book also provides an appendix which gives an introduction to C++ for programmers who use Java or C#.
The single CD accompanying the book contains Qt library in the source form for the Linux platform as well as for Windows and Mac platforms. I did not have any problems in compiling the source and installing the library in Linux using the instructions provided in the book. And within a little more than an hour (the time taken to compile the source code), I was able to start coding and compiling the examples given in the book. All in all, I find this book to be an invaluable guide in picking up skills in programming in the latest version of Qt (4.0).
Ravi Kumar likes to share his experiences in programming and in using Linux through his blog on Linux."
You can purchase C++ GUI Programming with Qt 4 from bn.com. Slashdot welcomes readers' book reviews -- to see your own review here, read the book review guidelines, then visit the submission page.
Its too bad its not LGPL (Score:2, Interesting)
Case in point: I am at a university and we write software for research. We cannot release the source for various reasons, but we also do not sell the software and our goals are strictly academic. And I can't justify the license fee to the PI (principal investigator) given the alternatives. Heck, even Microsoft Visual Studio is substantially cheaper.
Flame away. I always get flamed for this argument.
QT licensing problems (Score:3, Interesting)
The commercial license is tied to a named developer. That is, if I have a developer Dave who needs a QT license, I must buy a named license for Dave. It does not matter if I have unused licenses of QT lying around (which other developers don't need and are not even installed), I must still buy a license for Dave.
If Dave needs to go on a holiday or just dies and if I need Bill to complete the project using Dave's license, then the terms of the license prevents me from doing that. The license must be transferred over to Bill's name and this can be done only after 6 months! This is completely insane! Why would a company purchase a several-thousand-dollar license for a developer and face the prospect of having to purchase yet another license if the developer leaves the company / is unable to work on the project / is promoted to a non-coding role etc?
QT's commercial license fees are very high, and separate licenses are needed for each platform - that is, I need to buy QT license separately for Linux, Windows etc. Now, I perfectly understand that Trolltech can charge what they want as it is their product, but I do feel that they have made the product as unattractive an option as possible and this has resulted in huge losses to them. But again, that is their problem not mine.
I had the opportunity to review cross platform GUI toolkits for a huge project we were working on - the project was a very large public transportation project for Scandinavia and we needed a lot of licenses; I opted against QT (thereby denying them a huge order) because of these very unattractive terms in their licenses. I have had similar experiences with another project for a Finnish client as well. In both cases, I felt that QT was definitely the best framework for the job, but the licensing terms completely wiped out any of the technical advantages.
The primary problem with the QT commercial license is the fact that it makes it very difficult to bring in developers on a contract into a project for a short assignment. It becomes very difficult to reuse this license with yet another developer once the first developer's contract ends or if the first developer chooses to go elsewhere.
IMHO, Trolltech has an excellent product, but their legal and marketing departments needs to be overhauled.