My main motivation for writing this library is fun and getting some experience with Rust. As such, "there is already a library" does not count.
(The image is licensed under a Creative Commons Attribution-NonCommercial 2.5 License)
However, since you brought this topic up, let us look at some other libraries that allow accessing an X11 server from Rust. If you know about more libraries or want me to know that I got something wrong, feel free to tell me about them, for example by opening an issue.
I only found this on crates.io. The
Repository link is broken and documentation looks like someone dumped the result
of bindgen on the Xlib headers into a crate.
The Pure Rust bindings for X11 seem to contain hand-written code for parsing and sending X11 messages. Also, its README currently claims that this project is in an early state.
This seems to provide FFI wrappers around Xlib and various related libraries. I recently heard about this library because its unsafe code is unsound and causes undefined behaviour. This is basically all I know and heard about this library.
This project uses xcb-proto, the XML description of the X11 protocol that comes
from the libxcb project. Based on this XML, code is generated that provides a
foreign function interface to the various libxcb libraries. Due to its FFI
nature, this project contains many instances of unsafe. Worse, its
basic_window example indicates that users of this library must also use
unsafe for handling
events.
How can one ever be sure that there is nothing wrong with the unsafe one
writes?
I briefly looked at this project and found a NULL pointer dereference and re-discovered an already known leak.
The xcb-dl project seems to be similar to
rust-xcb: It provides FFI bindings to the libxcb C library. It uses the XML
description to generate this binding and the necessary types. It thus also has
many instances of unsafe and requires unsafe for using it.
The big difference to rust-xcb is that this library uses the libloading crate to dynamically load function pointers at runtime instead of linking at compile time.
"An implementation of the X Window System Protocol in Rust. 100% safe and mutex-free."
breadx uses the same generated bindings as x11rb. The project
claims that it is "generally faster (awaiting verification)".
One highlight is support for async. However, interactions with the X11 server
require &mut-access to the
Display.
Thus, the Display needs to be wrapped in a Mutex or RefCell to share with
multiple async tasks.
Another highlight is no_std support.
The xcb-sys crate uses bindgen to automatically generate a Rust API from libxcb's C headers. Everything is unsafe and as a user you are basically writing C code in Rust.
Put differently: There is lots of existing documentation (for C code) and reference code (written in C) that you can use. It is pretty much directly transferable to this library.
x11rb, the x11 rust bindings, is based on the XML description of the X11 protocol that comes from the libxcb project, similar to rust-xcb. However, instead of providing a foreign function interface to libxcb, the generated code reimplements the serialising and unserialising code that is provided by libxcb. libxcb is only used for receiving and sending opaque packets.
This reimplementation tries to avoid uses of unsafe and thus should enjoy
Rust's usual safety guarantees. After all, the best way to trust the unsafe code
coming out of your code generator is if your code generator does not generate
any unsafe code. Unsafe code is currently necessary for FFI binding to a handful
of functions from libxcb (see src/xcb_ffi.rs).
This means that this project is even safer than libxcb, because libxcb forces its users to blindly trust length fields that come from the X11 server.
The downside of this is possibly slower code. However, if your bottleneck is in talking to the X11 server, you are seriously doing something wrong.
Examples of the generated code can be found here. Feel free to suggest improvements to it.