Volume One: Xlib Programming Manual - Niksula

About This Manual
This manual describes the X library, the C Language programming interface to Version 11 of the X Window System. The
X library, known as Xlib, is the lowest level of programming interface to X. This library enables a programmer to write
applications with an advanced user interface based on windows on the screen, with complete network transparency, that
will run without changes on many types of workstations and personal computers.
Xlib is powerful enough to write effective applications without additional programming tools and is necessary for certain
tasks even in applications written with higher−level "toolkits."
There are a number of these toolkits for X programming, the most notable being the DEC/MIT toolkit Xt, the Andrew
toolkit developed by IBM and Carnegie−Mellon University, and the InterViews toolkit from Stanford. These toolkits are
still evolving, and only Xt is currently part of the X standard. Toolkits simplify the process of application writing
considerably, providing a number of widgets that implement menus, command buttons, and other common features of the
user interface.
This manual does not describe Xt or any other toolkit. That is done in Volumes Four and Five of our X Window System
series. Nonetheless, much of the material described in this book is helpful for understanding and using the toolkits, since
the toolkits themselves are written using Xlib and allow Xlib code to be intermingled with toolkit code.
Summary of Contents
This manual is divided into two volumes. This is the first volume, the Xlib Programming Manual. It provides a
conceptual introduction to Xlib, including tutorial material and numerous programming examples. Arranged by task or
topic, each chapter brings together a group of Xlib functions, describes the conceptual foundation they are based on, and
illustrates how they are most often used in writing applications (or, in the case of the last chapter, in writing window
managers). Volume One is structured so as to be useful as a tutorial and also as a task−oriented reference.
The second volume, the Xlib Reference Manual, includes reference pages for each of the Xlib functions, organized
alphabetically for ease of reference; a permuted index; and numerous appendices and quick reference aids.
Volume One and Volume Two are designed to be used together. To get the most out of the examples in Volume One, you
will need the exact calling sequences of each function from Volume Two. To understand fully how to use each of the
functions described in Volume Two, all but the most experienced X "hacker" will need the explanation and examples in
Volume One.
Both volumes include material from the original Xlib and X11 protocol documentation provided by MIT, as well as from
other documents provided on the MIT release tape. We have done our best to incorporate all of the useful information
from the MIT documentation, to correct code references we found to be in error, to reorganize and present it in a more
useful form, and to supplement it with conceptual material, tutorials, reference aids, and examples. In other words, this
manual is not only a replacement but is a superset of the MIT documentation.
Those of you familiar with the MIT documentation will recognize that each reference page in Volume Two includes the
detailed description of the routine found in Gettys, Newman, and Scheifler’s Xlib−C Language X Interface, plus, in many
cases, additional text that clarifies ambiguities and describes the context in which the routine would be used. We have also
added cross references to related reference pages and to where additional information can be found in Volume One.
How to Use This Manual
Volume One is intended as an introduction to all the basic concepts of X programming and also as a useful reference for
many of the most common programming techniques. It is divided into 14 chapters, which describe and demonstrate the use
of the X programming library, and numerous appendices.
You will find it necessary to read at least Chapters 1, 2, and 3 before attempting to program with the X library. Chapter 1,