WEBVTT captioned by bhavin192

NOTE Introduction

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Hello EmacsConf and hello fellow Emacs fans.

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My name is Michael Bauer, and I'm from Germany.

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I'm gonna talk to you about "Why and how Emacs

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should become a Wayland compositor."

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And it already kinda is a Wayland compositor.

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This talk is composed by Wayland and Emacs.

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If I'm talking about a Wayland compositor

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or Emacs as Wayland compositor,

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I mean it in the sense that

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EXWM is an X window manager. I hope you know EXWM.

NOTE Why

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So, why?

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Emacs can do Wayland now, that was a stopper

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before, and now it's solved with `pgtk` branch.

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It makes the Emacs toolbox bigger,

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which is always a good thing.

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And the cool thing about Wayland, which is not

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possible under X is, it can run standalone

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on the Linux kernel interface, or nested under X,

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or even nested under Wayland.

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The compositor features of Emacs doesn't mean

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it has to take over the whole output.

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It can use them, even if it's just like

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a normal window or normal program.

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And last reason is,

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I want to keep living inside Emacs

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and Wayland is the future, apparently.

NOTE EXWM use case

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EXWM use case is the first use case.

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You take a Wayland surface and put it inside

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an Emacs window. You see it right below.

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The video of me is a Wayland surface,

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and it's inside an Emacs window managed by Emacs.

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Emacs does the input, and the clipboard handling,

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and can insert itself here, and do great things.

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And it's a possibility to Lispify the Linux desktop,

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as Emacs Lispifies the command line.

NOTE XWidget use case

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The other use case is the XWidget use case.

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I don't know if you know XWidgets.

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It's embedded X windows inside Emacs.

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There's a web browser available in Emacs.

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With Wayland, you could embed anything that can

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create a Wayland surface like video, web, or 3D.

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Think OpenGL, something like

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EmacsGL would be possible.

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And we wouldn't have just images like we have so far.

NOTE How

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So, how to implement this Wayland compositor?

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I'm going to tell you how I did it,

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or I did this demo I'm showing you right now.

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First of all, how does Wayland work?

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Wayland is a protocol in XML.

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It's a server and client, and they share a set of

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objects, and the objects have methods.

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They are specified in the protocol,

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and Wayland also says how the server

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and client talk to each other.

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First blocker for Emacs becoming a Wayland

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compositor is that Emacs and Wayland both have

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their own event loop, and you can't merge them too.

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But you don't have to merge them

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because you can just make Emacs speak Wayland.

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So, Emacs becomes a Wayland client,

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and there's an extra server Emacs is talking to.

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So, we need a minimal Wayland server that does all

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the stuff Emacs can't do and do the rest in Emacs.

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---The minimal Wayland server, I did it in wlroots.

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That's the library behind Sway. I think it's

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the Wayland library to do stuff like this.

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I implemented four different things to make it work.

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It's these three letter acronyms on the left.

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It's Emacs, Wayland, and then it's a server,

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a client, a protocol, and buffers.

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The server is written in C and it's mostly tinywl.

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It's the example of wlroots,

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and it's around 1000 lines of code.

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ewc, the Wayland client in Emacs,

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is the thing I'm most proud of.

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It's 300 lines of code, and it is a

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fully featured Wayland client in Emacs.

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With this, Emacs can speak Wayland,

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and then I implemented Emacs Wayland protocol.

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It more or less allows Emacs to become a Wayland

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window manager, so it's not actually the compositor.

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The compositor stays in C, but Emacs is

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now a Wayland window manager!

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And the last thing is Emacs Wayland buffers.

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It's the window manager part.

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It's around 500 lines of code,

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and it does the buffer management inside

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Emacs windows, or floating right like you see me

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now floating on the right.

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It works, but it is still buggy,

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and it is also missing input handling,

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so there's more code to come for this to work.

NOTE Caveats

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Some caveats about this approach.

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wlroots is around 60 kilo LoCs (Line of Code)

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and in active development.

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They have like a slogan 60 kilo locs of code

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you had to write anyway to make a Wayland

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compositor. And no, you don't have to write it.

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But I still remember when it was like 50 kilo locs,

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and now it's 60. And it's like a moving target.

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I think it could be quite a lot of work

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to keep up with it.

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Yeah, it could be quite a bit of work.

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Some windows don't like to keep the aspect ratios.

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You tell them and you have to crop them.

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And the interface I use in wlroots for doing this,

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`wlr_scene`, can't do cropping yet,

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so this doesn't work.

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Another problem is with GTK.

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Once Wayland is enabled and it stays on.

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This doesn't make sense.

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Okay, if you kill the Wayland server,

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GTK kills Emacs, that's not a good thing.

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And it's still a bit of work and fussing needed

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to get this to work reliably.

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It's quite buggy right now.

NOTE Call to action

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And that brings me to my call to action.

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I think making Emacs Wayland capable is

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a further step to make an Emacs OS.

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It gains output and input handling.

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Output handling is already there,

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input handling is still missing,

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but Emacs can manage monitors, outputs,

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different frames if it's like nested,

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And inputs, keyboards, simulation keys,

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stuff like that.

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We could use it in more ways for Emacs display, maybe.

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Wayland just manages simple pixel buffers,

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so it's a protocol for managing pixel buffers.

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And in a sense, we could go back to

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the old X ways and maybe even ditch GTK.

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I don't know, but why need it?

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We can composite without it.

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Let's make buffer menus, buffer world, buffer.

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Emacs Wayland protocol, like I did it,

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allows a very concise design, and it allows

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to improve on the EXWM code base.

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And I wrote KISS style because EXWM has

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workspace management integrated.

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I don't think that's needed, like Emacs does it.

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Why do you have to do something extra?

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So why do it?

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To finish the call to action,

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if this is the thing you want to see in Emacs,

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maybe you want to get involved, have some ideas,

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so we could discuss it.

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I'm looking forward to discuss with you

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and hear your questions and ideas.

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I want to say a big thank you to the

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organizers of EmacsConf and the other speakers

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for making this event possible.

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Thank you, and see you.