The authors provide a detailed examination and illustration of the X Window System for creating user interfaces. The book uses the standard X Toolkit consisting of Xt Intrinsics and widgets from the OPEN LOOK Intrinsics Toolkit (OLIT). It is based on the X11R4 release of Xlib and version 3.0 of OLIT. The strengths of this book lie in its thoroughness and extensive use of examples. The book is a well-organized presentation of many detailed functions. It seems to cover Xt Intrinsics and OLIT completely. This material, because it is so detailed, does not lend itself to a precise presentation in prose. The extensive use of examples throughout most chapters is useful for illustrating this miscellany of functions, each of which has many complex combinations of arguments.
This book is aimed at those who plan extensive work with X. It is not organized in the spiral manner that would make it more palatable for the novice or as a textbook. Its organization makes it useful as a reference book for the more advanced programmer. Novices who attempt an introduction to X Window programming through this book should be warned to proceed slowly, trying many of the examples as they proceed.
The first of the 14 chapters gives an introduction to the X Window System. It includes an explanation of the client-server model, X resources, and basic window concepts. The X Window concepts of requests, events, and window management are described. This chapter is written at a novice level.
The book’s reading level changes immediately in chapter2 as the authors plunge into the details of Xt Intrinsic. This chapter, like all the subsequent chapters, is liberally sprinkled with function prototypes and their explanations along with example C programs. To understand and remember these functions, the reader will find it useful to follow the explanations by writing the C programs presented in the text. Chapter 2 uses a “memo” example to illustrate these functions.
Chapter 3 presents X functions to manage resources in an X application. X resources are windows, fonts, and internal data used by widgets, or user-customizable data used by X Intrinsics. The purpose of the fourth chapter is to explain the widgets that compose the OLIT Widget Set. This long chapter (114 pages) is central to the book. It includes several examples of the use of these widget functions.
Chapter 5 explains how events can be handled in Xt Intrinsics. An event is an indication that some condition has changed, sent to a client by an X server. Chapters 6 through 11 provide more detail on specific aspects of X programming. Chapter 6 deals with the use of color, including a colormap editor example. Chapter 7 describes functions to manipulate raster images, including pixmaps, bitmaps, and XImages. The next chapter describes how to create and manipulate graphics contexts. Chapter 9 gives details about the use of text and fonts. Chapter 10, “Using the X Graphics Primitives,” explains the usage of Xlib functions to draw images with points, lines, and arcs. It includes a simple drawing program. Chapter 11 describes X interprocess communication, which allows applications to communicate with each other.
Chapters 12, 13, and 14 explain how programmers can construct their own widgets rather than relying entirely on those in the widget set. Chapter 12 explains the architecture of a widget and describes how the simplest class of widgets, those used to display information, is constructed. Chapter13 describes the construction of composite widgets, which manage other widgets. The last chapter describes constraint widgets, which control their child widgets.
This book includes five appendices. Appendix A gives a one-page diagram of the OLIT class tree, which can serve as an index to this extensive set of library functions. AppendixB is extensive (82 pages) and will probably be one of the most useful resources in the entire book. It gives a complete description of each of the OLIT widgets. Each widget is described on one or two pages, with a list of necessary include files, arguments, and resource attributes. AppendixC is a list of key and button bindings. AppendixD gives the contents of LibXs.h. Appendix E gives the code for some pixmaps.
The index includes major topics and concepts and all the functions explained throughout the book. This arrangement is useful if the reader knows the name of a function and needs more information. The function names are generally descriptive enough to be guessed, but it would be useful to have another index to this list of functions for use when the name of the function is unknown.
