Hello, yesterday I officially released Louvre v1.0.0, a C++ library designed for building Wayland compositors with a primary focus on ease of development. It provides a default method for handling protocols, input events, and rendering, which you can selectively and progressively override as required, allowing you to see a functional compositor from day 1.
It supports multi-GPU setups, multi-session (TTY switching), and offers various rendering options, including a scene and view system that automatically repaints only the damaged (changing) regions during a frame. Because it uses multiple threads, it can maintain a high FPS rate with v-sync enabled when rendering complex scenarios. In contrast, single-threaded compositors often experience a rapid drop in FPS, for example, from 60 to 30 fps, due to "dead times" while waiting for a screen vblank, leading to the skipping of frames.
The library is freely available, open source, thoroughly documented, includes examples, and features a detailed tutorial.
You can find it here: https://github.com/CuarzoSoftware/Louvre
I hope it proves useful for you. If you decide to use it and encounter any doubts or wish to contribute to its development, please don't hesitate to reach out.
Greetings!
Ohh, that's cool. How far do you want to go with this? I had the idea of using a custom wayland protocol to make per-app global menus instead of per-window so you can have an app open without any windows, like on macOS, in the compositor I wanted to write. However writing a compositor using wlroots is still incredibly difficult if you have no prior experience so the whole thing didn't get very far yet. If that's something you want to do too, I'd be very interested in this.
(Speaking of, why did you decide not to build this on top of wlroots?)
I actually already created a library for that called Heaven (https://github.com/CuarzoSoftware/Heaven), but I want to rewrite it to make it simpler and add backends for different IPC mechanisms (Unix domain sockets and D-Bus).
It allows apps to create as many menu bars as they want. The idea is that when one of its toplevel windows is activated, it can notify the “topbar app” to display a specific menu bar. The compositor also informs the “topbar app” about the currently active client. So, it has three APIs: one for apps, another for the “topbar app,” and another for the compositor. Apps are identified by their PID.
Now, with respect to the second question, a long time ago, I tried to create a compositor using QtWayland, which had the most documentation at that time. However, it had some problems with certain interfaces that made the compositor crash. So, I then looked for wlroots but could find no documentation whatsoever, so I decided to start from scratch. As time passed, I began to learn and understand how protocols work, realizing that one of the most challenging things was implementing protocols correctly, as there are too many interfaces that depend on each other, and you need to implement them all before you can see results and validate that it works. That’s why I decided to create this lib, even as my university thesis, with the focus of offering a default and basic implementation of each protocol so that developers can see a functional compositor from the start and then gradually and specifically override whatever they need, being able to validate each feature they add immediately. Of course, there are many other complicated things I had to learn, such as the DRM/KMS API, buffer sharing through DMA, among other stuff. I really appreciate wlroots, though. I learned a lot by analyzing its source code, and surely today I would be able to create a compositor with it, hahaha.
Well that's awesome. I'll take a closer look at this in a couple days. Maybe even contribute if I have the time :P
That would be great! 😀