Proposal for wmfocus 2.0

[markstos]

Why 2.0?

Building support for multiple window managers has been problematic. Currently, only one can readily be compiled-in at a time. Support for Sway was never merged, and support EWMH-compliant window managers has not been completed either.

The STDIN branch demonstrated how window-manager-specific bits can be externalized, so new window managers can supported without modifying this software.

wmfocus 2.0 can build on that approach, which can both simplify the code base while making it easier to support multiple window managers.

Different window managers need different syntax. Support for some popular window managers can be built-in, while it can be easy to document and share configs for others.

This design will require some breaking changes, hence: 2.0.

The Window format to expect on STDIN

The following space-separated line-based format will be expecteds to be received on STDIN:

WINDOW-ID X Y WIDTH HEIGHT 1-IF-FOCUSED

Here X and Y corresponds to the upper-left corner of windows. Passing the details for visible windows only is expected.

Example:

swaymsg -t get_tree | jq -r '.. | (.nodes? // empty)[] | select(.pid and .visible) | "\(.id) \(.rect.x) \(.rect.y) \(.rect.width) \(.rect.height) \(.focused==true)"' | wmfocus

Native support for popular window managers

If no input is given on STDIN, wmfocus could possibly detect a small number of officially supported window managers and gather the input directly.

For example, checking if XDG_CURRENT_DESKTOP=sway to indicate sway is running, and then internally call swaymsg to details on stdin.

Using a Rust JQ library instead of calling the jq binary would a way to still use the JQ syntax but without adding an external dependency.

https://docs.rs/jq-rs/latest/jq_rs/

The JQ syntax to support bpswm using the STDIN patch is as follows, while the i3 syntax would be very close or Sways.

#!/usr/bin/jq -rf

.monitors[] |
.focusedDesktopId as $d |
.desktops[] |
select(.id==$d) |
.focusedNodeId as $fw |
getpath(paths(.client?!=null and .hidden==false)) |
.id as $w |
.client |
(if .state == "floating" then .floatingRectangle else .tiledRectangle end) |
"\($w) \(.x) \(.y) \(.width) \(.height) \($fw==$w)"

Wayland Support

wmfocus 2.0 should support Wayland. Using XWayland to draw windows can result in wmfocus getting "stuck" in some cases. Native Wayland windows would solve that. Below is some example code to draw a window on Wayland.

use std::{convert::TryInto, time::Duration};

use calloop::{EventLoop, LoopHandle};
use smithay_client_toolkit::{
    compositor::{CompositorHandler, CompositorState},
    delegate_compositor, delegate_keyboard, delegate_output, delegate_pointer, delegate_registry,
    delegate_seat, delegate_shm, delegate_xdg_shell, delegate_xdg_window,
    output::{OutputHandler, OutputState},
    registry::{ProvidesRegistryState, RegistryState},
    registry_handlers,
    seat::{
        keyboard::{KeyEvent, KeyboardHandler, Modifiers},
        pointer::{PointerEvent, PointerEventKind, PointerHandler},
        Capability, SeatHandler, SeatState,
    },
    shell::{
        xdg::{
            window::{Window, WindowConfigure, WindowDecorations, WindowHandler},
            XdgShell,
        },
        WaylandSurface,
    },
    shm::{
        slot::{Buffer, SlotPool},
        Shm, ShmHandler,
    },
};
use wayland_client::{
    globals::registry_queue_init,
    protocol::{wl_keyboard, wl_output, wl_pointer, wl_seat, wl_shm, wl_surface},
    Connection, QueueHandle, WaylandSource,
};

fn main() {
    env_logger::init();

    // All Wayland apps start by connecting the compositor (server).
    let conn = Connection::connect_to_env().unwrap();

    // Enumerate the list of globals to get the protocols the server implements.
    let (globals, event_queue) = registry_queue_init(&conn).unwrap();
    let qh = event_queue.handle();
    let mut event_loop: EventLoop<SimpleWindow> =
        EventLoop::try_new().expect("Failed to initialize the event loop!");
    let loop_handle = event_loop.handle();
    WaylandSource::new(event_queue).unwrap().insert(loop_handle).unwrap();

    // The compositor (not to be confused with the server which is commonly called the compositor) allows
    // configuring surfaces to be presented.
    let compositor = CompositorState::bind(&globals, &qh).expect("wl_compositor not available");
    // For desktop platforms, the XDG shell is the standard protocol for creating desktop windows.
    let xdg_shell = XdgShell::bind(&globals, &qh).expect("xdg shell is not available");
    // Since we are not using the GPU in this example, we use wl_shm to allow software rendering to a buffer
    // we share with the compositor process.
    let shm = Shm::bind(&globals, &qh).expect("wl shm is not available.");

    // A window is created from a surface.
    let surface = compositor.create_surface(&qh);
    // And then we can create the window.
    let window = xdg_shell.create_window(surface, WindowDecorations::RequestServer, &qh);
    // Configure the window, this may include hints to the compositor about the desired minimum size of the
    // window, app id for WM identification, the window title, etc.
    window.set_title("A wayland window");
    // GitHub does not let projects use the `org.github` domain but the `io.github` domain is fine.
    window.set_app_id("io.github.smithay.client-toolkit.SimpleWindow");
    window.set_min_size(Some((256, 256)));

    // In order for the window to be mapped, we need to perform an initial commit with no attached buffer.
    // For more info, see WaylandSurface::commit
    //
    // The compositor will respond with an initial configure that we can then use to present to the window with
    // the correct options.
    window.commit();

    // We don't know how large the window will be yet, so lets assume the minimum size we suggested for the
    // initial memory allocation.
    let pool = SlotPool::new(256 * 256 * 4, &shm).expect("Failed to create pool");

    let mut simple_window = SimpleWindow {
        // Seats and outputs may be hotplugged at runtime, therefore we need to setup a registry state to
        // listen for seats and outputs.
        registry_state: RegistryState::new(&globals),
        seat_state: SeatState::new(&globals, &qh),
        output_state: OutputState::new(&globals, &qh),
        shm,

        exit: false,
        first_configure: true,
        pool,
        width: 256,
        height: 256,
        shift: None,
        buffer: None,
        window,
        keyboard: None,
        keyboard_focus: false,
        pointer: None,
        loop_handle: event_loop.handle(),
    };

    // We don't draw immediately, the configure will notify us when to first draw.
    loop {
        event_loop.dispatch(Duration::from_millis(16), &mut simple_window).unwrap();

        if simple_window.exit {
            println!("exiting example");
            break;
        }
    }
}

struct SimpleWindow {
    registry_state: RegistryState,
    seat_state: SeatState,
    output_state: OutputState,
    shm: Shm,

    exit: bool,
    first_configure: bool,
    pool: SlotPool,
    width: u32,
    height: u32,
    shift: Option<u32>,
    buffer: Option<Buffer>,
    window: Window,
    keyboard: Option<wl_keyboard::WlKeyboard>,
    keyboard_focus: bool,
    pointer: Option<wl_pointer::WlPointer>,
    loop_handle: LoopHandle<'static, SimpleWindow>,
}

impl CompositorHandler for SimpleWindow {
    fn scale_factor_changed(
        &mut self,
        _conn: &Connection,
        _qh: &QueueHandle<Self>,
        _surface: &wl_surface::WlSurface,
        _new_factor: i32,
    ) {
        // Not needed for this example.
    }

    fn frame(
        &mut self,
        conn: &Connection,
        qh: &QueueHandle<Self>,
        _surface: &wl_surface::WlSurface,
        _time: u32,
    ) {
        self.draw(conn, qh);
    }
}

impl OutputHandler for SimpleWindow {
    fn output_state(&mut self) -> &mut OutputState {
        &mut self.output_state
    }

    fn new_output(
        &mut self,
        _conn: &Connection,
        _qh: &QueueHandle<Self>,
        _output: wl_output::WlOutput,
    ) {
    }

    fn update_output(
        &mut self,
        _conn: &Connection,
        _qh: &QueueHandle<Self>,
        _output: wl_output::WlOutput,
    ) {
    }

    fn output_destroyed(
        &mut self,
        _conn: &Connection,
        _qh: &QueueHandle<Self>,
        _output: wl_output::WlOutput,
    ) {
    }
}

impl WindowHandler for SimpleWindow {
    fn request_close(&mut self, _: &Connection, _: &QueueHandle<Self>, _: &Window) {
        self.exit = true;
    }

    fn configure(
        &mut self,
        conn: &Connection,
        qh: &QueueHandle<Self>,
        _window: &Window,
        configure: WindowConfigure,
        _serial: u32,
    ) {
        println!("Window configured to: {:?}", configure);

        self.buffer = None;
        self.width = configure.new_size.0.map(|v| v.get()).unwrap_or(256);
        self.height = configure.new_size.1.map(|v| v.get()).unwrap_or(256);

        // Initiate the first draw.
        if self.first_configure {
            self.first_configure = false;
            self.draw(conn, qh);
        }
    }
}

impl SeatHandler for SimpleWindow {
    fn seat_state(&mut self) -> &mut SeatState {
        &mut self.seat_state
    }

    fn new_seat(&mut self, _: &Connection, _: &QueueHandle<Self>, _: wl_seat::WlSeat) {}

    fn new_capability(
        &mut self,
        _conn: &Connection,
        qh: &QueueHandle<Self>,
        seat: wl_seat::WlSeat,
        capability: Capability,
    ) {
        if capability == Capability::Keyboard && self.keyboard.is_none() {
            println!("Set keyboard capability");
            let keyboard = self
                .seat_state
                .get_keyboard_with_repeat(
                    qh,
                    &seat,
                    None,
                    self.loop_handle.clone(),
                    Box::new(|_state, _wl_kbd, event| {
                        println!("Repeat: {:?} ", event);
                    }),
                )
                .expect("Failed to create keyboard");

            self.keyboard = Some(keyboard);
        }

        if capability == Capability::Pointer && self.pointer.is_none() {
            println!("Set pointer capability");
            let pointer = self.seat_state.get_pointer(qh, &seat).expect("Failed to create pointer");
            self.pointer = Some(pointer);
        }
    }

    fn remove_capability(
        &mut self,
        _conn: &Connection,
        _: &QueueHandle<Self>,
        _: wl_seat::WlSeat,
        capability: Capability,
    ) {
        if capability == Capability::Keyboard && self.keyboard.is_some() {
            println!("Unset keyboard capability");
            self.keyboard.take().unwrap().release();
        }

        if capability == Capability::Pointer && self.pointer.is_some() {
            println!("Unset pointer capability");
            self.pointer.take().unwrap().release();
        }
    }

    fn remove_seat(&mut self, _: &Connection, _: &QueueHandle<Self>, _: wl_seat::WlSeat) {}
}

impl KeyboardHandler for SimpleWindow {
    fn enter(
        &mut self,
        _: &Connection,
        _: &QueueHandle<Self>,
        _: &wl_keyboard::WlKeyboard,
        surface: &wl_surface::WlSurface,
        _: u32,
        _: &[u32],
        keysyms: &[u32],
    ) {
        if self.window.wl_surface() == surface {
            println!("Keyboard focus on window with pressed syms: {keysyms:?}");
            self.keyboard_focus = true;
        }
    }

    fn leave(
        &mut self,
        _: &Connection,
        _: &QueueHandle<Self>,
        _: &wl_keyboard::WlKeyboard,
        surface: &wl_surface::WlSurface,
        _: u32,
    ) {
        if self.window.wl_surface() == surface {
            println!("Release keyboard focus on window");
            self.keyboard_focus = false;
        }
    }

    fn press_key(
        &mut self,
        _conn: &Connection,
        _qh: &QueueHandle<Self>,
        _: &wl_keyboard::WlKeyboard,
        _: u32,
        event: KeyEvent,
    ) {
        println!("Key press: {event:?}");
    }

    fn release_key(
        &mut self,
        _: &Connection,
        _: &QueueHandle<Self>,
        _: &wl_keyboard::WlKeyboard,
        _: u32,
        event: KeyEvent,
    ) {
        println!("Key release: {event:?}");
    }

    fn update_modifiers(
        &mut self,
        _: &Connection,
        _: &QueueHandle<Self>,
        _: &wl_keyboard::WlKeyboard,
        _serial: u32,
        modifiers: Modifiers,
    ) {
        println!("Update modifiers: {modifiers:?}");
    }
}

impl PointerHandler for SimpleWindow {
    fn pointer_frame(
        &mut self,
        _conn: &Connection,
        _qh: &QueueHandle<Self>,
        _pointer: &wl_pointer::WlPointer,
        events: &[PointerEvent],
    ) {
        use PointerEventKind::*;
        for event in events {
            // Ignore events for other surfaces
            if &event.surface != self.window.wl_surface() {
                continue;
            }

            match event.kind {
                Enter { .. } => {
                    println!("Pointer entered @{:?}", event.position);
                }
                Leave { .. } => {
                    println!("Pointer left");
                }
                Motion { .. } => {}
                Press { button, .. } => {
                    println!("Press {:x} @ {:?}", button, event.position);
                    self.shift = self.shift.xor(Some(0));
                }
                Release { button, .. } => {
                    println!("Release {:x} @ {:?}", button, event.position);
                }
                Axis { horizontal, vertical, .. } => {
                    println!("Scroll H:{horizontal:?}, V:{vertical:?}");
                }
            }
        }
    }
}

impl ShmHandler for SimpleWindow {
    fn shm_state(&mut self) -> &mut Shm {
        &mut self.shm
    }
}

impl SimpleWindow {
    pub fn draw(&mut self, _conn: &Connection, qh: &QueueHandle<Self>) {
        let width = self.width;
        let height = self.height;
        let stride = self.width as i32 * 4;

        let buffer = self.buffer.get_or_insert_with(|| {
            self.pool
                .create_buffer(width as i32, height as i32, stride, wl_shm::Format::Argb8888)
                .expect("create buffer")
                .0
        });

        let canvas = match self.pool.canvas(buffer) {
            Some(canvas) => canvas,
            None => {
                // This should be rare, but if the compositor has not released the previous
                // buffer, we need double-buffering.
                let (second_buffer, canvas) = self
                    .pool
                    .create_buffer(
                        self.width as i32,
                        self.height as i32,
                        stride,
                        wl_shm::Format::Argb8888,
                    )
                    .expect("create buffer");
                *buffer = second_buffer;
                canvas
            }
        };

        // Draw to the window:
        {
            let shift = self.shift.unwrap_or(0);
            canvas.chunks_exact_mut(4).enumerate().for_each(|(index, chunk)| {
                let x = ((index + shift as usize) % width as usize) as u32;
                let y = (index / width as usize) as u32;

                let a = 0xFF;
                let r = u32::min(((width - x) * 0xFF) / width, ((height - y) * 0xFF) / height);
                let g = u32::min((x * 0xFF) / width, ((height - y) * 0xFF) / height);
                let b = u32::min(((width - x) * 0xFF) / width, (y * 0xFF) / height);
                let color = (a << 24) + (r << 16) + (g << 8) + b;

                let array: &mut [u8; 4] = chunk.try_into().unwrap();
                *array = color.to_le_bytes();
            });

            if let Some(shift) = &mut self.shift {
                *shift = (*shift + 1) % width;
            }
        }

        // Damage the entire window
        self.window.wl_surface().damage_buffer(0, 0, self.width as i32, self.height as i32);

        // Request our next frame
        self.window.wl_surface().frame(qh, self.window.wl_surface().clone());

        // Attach and commit to present.
        buffer.attach_to(self.window.wl_surface()).expect("buffer attach");
        self.window.commit();
    }
}

delegate_compositor!(SimpleWindow);
delegate_output!(SimpleWindow);
delegate_shm!(SimpleWindow);

delegate_seat!(SimpleWindow);
delegate_keyboard!(SimpleWindow);
delegate_pointer!(SimpleWindow);

delegate_xdg_shell!(SimpleWindow);
delegate_xdg_window!(SimpleWindow);

delegate_registry!(SimpleWindow);

impl ProvidesRegistryState for SimpleWindow {
    fn registry(&mut self) -> &mut RegistryState {
        &mut self.registry_state
    }
    registry_handlers![OutputState, SeatState,];
}

[markstos]

CC: @ortango @b0o

[svenstaro]

Interesting proposition. It would certainly allow for easier user-sided extension as long as the window managers allow some kind of export of the desktop tree. I'm not sure the startup slowdown would be noticeable, I think probably not.

I don't really see big reasons not to do it like this. I don't personally use Wayland but I hope Cairo works natively with it somehow. I'd much prefer if the rendering system were somehow shared between X and Wayland.

That said, is this something you'd like to work on?

[markstos]

I looked at it a little this weekend, but don't find the Rust/Wayland docs easy to follow, being a beginner at both. As far as I got was the working code I included above to draw a Wayland window, but there are other details I still need to learn, how add text to the window.

If I work on this, I'd make a Wayland-only solution. X11 is on life support [1] and major toolkits like GTK are looking at dropping support for it. [2].

1. https://www.theregister.com/2020/10/30/x_server_lead_maintainer_declares/
2. https://www.phoronix.com/news/GTK5-Might-Drop-X11

Otherwise, the already published STDIN published has already implemented that part. I confirmed this weekend it compiles, runs and works with Sway, while the other author tested it with bspwm.

[markstos]

Putting my own interest in Wayland aside, even creating a "2.0" based on accepting window details on STDIN would make wmfocus immediately accessible to people using a wide range of window managers, which could in turn attract more project contributors... one of which might want to help with adding Wayland support. :) And since the STDIN branch is already working, it's just a matter of improving the documentation around that and preparing it for a release as a breaking change.

I could help with that part and Wayland support could be pushed to a later release.

[markstos]

Here's some refined pseudo-code for wmfocus 2.0, which drops Wayland support as goal for that milestone. This iterations preserves the performance and backcompat for Sway and i3 of the current version.

listOfWindows=[];

if (STDIN) {
  validateInput()
  // Process STDIN as "WINDOW-ID X Y WIDTH HEIGHT 1-IF-FOCUSED"
  listofWindows = STDIN;
}
else if (XDG_CURRENT_DESKTOP=sway) {
 listOfWindows = visible windows from Sway IPC;
}
else if (XDG_CURRENT_DESKTOP=i3) {
   listOfWindows = visible windows from i3 IPC;
}
else {
  throw "No supported WM found in XDG_CURRENT_DESKTOP and no input on STDIN"
}

This design removes the idea of compiling different WMs as competing features. The intent is that perhaps only Sway and i3 would get special treatment-- because it's hard to maintain support for a WMs the authors are not using-- and other WMs would use the STDIN API.

Also, I found a better example of Rust code to draw windows on Wayland. This uses GTK instead of Smithay, but the code is clear, concise and easy to read, and includes an example of formatting text in a simple window using Pango markup.

https://github.com/ilya-zlobintsev/sway-marker/blob/master/src/main.rs

[markstos]

Someone implemented a tool like this for Sway, so I'll be using that instead:

https://github.com/edzdez/sway-easyfocus