Xlib --- C Language X Interface is a reference guide to the low-level C language interface to the X Window System protocol. It is neither a tutorial nor a user's guide to programming the X Window System. Rather, it provides a detailed description of each function in the library as well as a discussion of the related background information. Xlib --- C Language X Interface assumes a basic understanding of a graphics window system and of the C programming language. Other higher-level abstractions (for example, those provided by the toolkits for X) are built on top of the Xlib library. For further information about these higher-level libraries, see the appropriate toolkit documentation. The X Window System Protocol provides the definitive word on the behavior of X. Although additional information appears here, the protocol document is the ruling document.
To provide an introduction to X programming, this chapter discusses: