[−][src]Module breadx::tutorials::intro
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+ and Qt 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
breadxcan 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.)
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.