// MIT/Apache2 License

//! In this series of tutorials, I will teach you how to use `breadx` and the X Window System Protocol to the
//! best of my ability. This tutorial assumes at least a beginner's knowledge of how to use Rust. I will not
//! attempt to teach you Rust in this tutorial; people who are much better at this kind of thing than I am
//! have already covered this subject extensively.
//!
//! # Why you should use X
//!
//! Here, I try to convince you that you, the reader, do not need to use this library. If you want to construct
//! a graphical application, [GTK+](https://www.gtk.org/) and [Qt](https://www.qt.io/) are very mature libraries
//! that support an astounding variety of platforms. Hell, we're living in 2020. The idea of a webpage has
//! replaced the GUI application, and they are usually much easier to set up.
//!
//! If you're still reading, I'm going to assume you fall into one of the following categories:
//!
//! * **You want a smaller application size.** GTK+ and Qt are huge, monolithic libraries. Both of them use
//!   some kind of metaprogramming framework that can make code written in the framework almost alien to its
//!   mother language. Static linking with either library is almost impossible. Meanwhile, Xlib is a smalller
//!   library. If compatibility with non-Unix platforms is not a concern, using only `breadx` can lead to
//!   significantly smaller program sizes.
//! * **You're writing the GUI library.** Most GUI libraries use some kind of underlying interface to the
//!   system to draw their windows. For Unix-based systems, X is the dominant choice.
//! * **You're just interested in learning how X works.** There's nothing wrong with learning more about how
//!   your computer ticks.
//!
//! In which case, welcome aboard. Let's go over what goes on behind the scenes.
//!
//! # The X Window System Protocol
//!
//! (Note: Most information derived from [here](https://en.wikipedia.org/wiki/X_Window_System).)
//!
//! X originated from Jim Gettys and Bob Scheifler at MIT in 1984. At this point, several other display systems
//! had been proposed, such as Xerox's "Alto", Apple's "Lisa" and "Macintosh" and, most notably, the W Window
//! System. X was originally created after Scheifler took code from the W Window System and rewrote it to be
//! asynchronous rather than synchronous. He called this "X".
//!
//! X takes place over a connection between a client and a server. In your average X program, the "client" is a
//! program and the server is another program on the same computer. Four principal types of data are sent
//! across this connection:
//!
//! * **Requests** refer to data sent from the client to the server, and generally act as an invocation of some
//!   kind of behavior. For instance, creating a window or moving a window all involve requests.
//! * **Replies** are sent by the server in response to requests. Every request will have either zero or one
//!   replies associated with it. For instance, a request to get the dimensions of a window will be answered
//!   with a reply containing those dimensions.
//! * **Events** are sent by the server in response to the hardware. For instance, the user clicking the mouse
//!   pressing a key on the keyboard will be translated to an event.
//! * **Errors** are sent by the server in response to invalid behavior. For instance, if the user sends a
//!   request using a window that's already been used, the server will send back a `WindowError`.
//!
//! Pretty much everything you need to know for now is that X is a connection to a server that controls
//! what appears on your screen.
//!
//! [In the next tutorial, we'll learn how to create a connection to the X server and use that to display a window.](../basics/index.html)