A listing of random software, tips, tweaks, hacks, and tutorials I made for Ubuntu
Idea: Non-windowing display server
August 26, 2015Posted by on
For the TL;DR folk who are concerned with the title: It’s not an alternative to wayland or X11. It’s layer that wayland compositors (or other) can use.
As a quick foreward: I’m still a newbie at this field. While I try my best to avoid inaccuracies, there might be a few things I state here that are wrong, feel free to correct me!
Wayland is mainly a windowing protocol. It allows clients to draw windows (or, as the wayland documentation puts it, “surfaces”), and receive input from those surfaces. A wayland server (or “compositor”) has the task of drawing these surfaces, and providing the input to the clients. That is the specification.
However, where does a compositor draw these surfaces to? How does the compositor receive input? It has to provide many backends for various methods of drawing the composited surface. For example, the weston compositor has support for drawing the composited surface using 7 different backends (DRM, Linux Framebuffer, Headless [a fake rendering device], RDP, Raspberry Pi, Wayland, and X11). The amount of work put into making these backends work must be incredible, which is exactly where the problem relies in: it’s arguably too much work for a developer to put in if they want to make a new compositor.
That’s not the only issue though. Another big problem is that there is then no standard way to configure the display. Say you wanted a wayland compositor to change the video resolution to 800×600. The only way to do that is to use a compositor-specific extension to the protocol, since the protocol, AFAIK, has no method for changing the video resolution — and rightfully so. Wayland is a windowing protocol, not a display protocol.
My idea is to create a display server that doesn’t handle windowing. It handles display-related things, such as drawing pixels on the screen, changing video mode, etc… Wayland compositors and other programs that require direct access to the screen could then use this server and trust that the server will take care of everything display-related for them.
I believe that this would enable for much simpler code, and add a good deal more power and flexibility.
To give a more graphic description (forgive my horrible diagraming skills):
I didn’t talk about the input server, but it’s the same idea as the display server: Have a server dedicated to providing input. Of course, if the display server uses something like SDL as the backend, it may have to also provide the input server, due to the SDL library, AFAIK, doesn’t allow a program to access the input of another program.
This is an idea I have toyed around with for some time now (ever since I tried writing my own wayland compositor, in fact! XD), so I’m curious as to what people think of it. I would be more than happy to work with others to implement this.