Milad Alizadeh
dbfc06519a
A switcher to replace a wlthumbs + rofi pipeline, with the same look (gruvbox, ceil(sqrt(n)) columns capped at 4, 16:9 tiles, a yellow selection filling the element padding) but no thumbnails anywhere. Each window is captured straight into a wl_shm buffer that is handed to its own wl_subsurface, with wp_viewporter giving the compositor the rectangle to scale it into. So there is no PNG encode, no scaler, no full-resolution bitmap in this process, and the capture buffers are never even mapped here — the compositor writes those pages and samples them again for display. Opens in ~65ms for 8 windows (55ms of which is the compositor reading pixels back out of the GPU) and holds ~9MB of RSS. All capture sessions are opened before a single roundtrip and every frame goes in flight together, the same batching wlthumbs uses, because the readback is bandwidth-bound rather than latency-bound. sway remains the source of truth: the window list, the con_ids and the focusing all come from its IPC socket, joined to the Wayland side by foreign_toplevel_identifier. Navigation reads raw evdev keycodes so it is layout-independent, which does mean virtual-keyboard clients that invent their own keymap can't drive it; that resolves when filtering brings xkb. Labels, type-to-filter and live previews are next.
3.4 KiB
wlgrid
A window switcher for wlroots compositors: a thumbnail grid overlay that looks like a rofi theme, and focuses the window you pick.
It replaces a wlthumbs | rofi pipeline. The difference is that no thumbnails
exist: each window is captured straight into a wl_shm buffer that is handed to
its own wl_subsurface, and wp_viewporter tells the compositor which rectangle
to scale it into. There is no image encoding, no scaler, and no full-resolution
bitmap in this process — which is also why it holds ~9 MB of RSS and appears in
about 60 ms.
sway-tree 0.6ms window list + con_ids over sway IPC
toplevels 0.2ms ext-foreign-toplevel-list handles
constraints 1.5ms every capture session's buffer size, in one roundtrip
capture 55.0ms 8 windows, all frames in flight at once
mapped 4.2ms layer surface + subsurfaces on screen
The capture phase is the compositor reading full-resolution window pixels out of the GPU. It is bandwidth-bound (~1.1 GB/s here) and unaffected by how large the thumbnails are.
Status
Working, and usable as a switcher today: a static grid with keyboard navigation. Labels, filtering and live previews are next — see the roadmap.
Usage
wlgrid [--print] [--verbose] [--timeout SECS]
--printwrites the selected swaycon_idto stdout instead of focusing it--verboseprints phase timings and how many windows were captured--timeout SECSexits after a deadline (an escape hatch: the overlay takes an exclusive keyboard grab)
Bind it in sway:
bindsym $mod+Tab exec wlgrid
| key | |
|---|---|
→ ← / Tab Shift+Tab |
next / previous window |
↑ ↓ |
move a row |
Home End |
first / last |
Enter |
focus the selection |
Escape / q |
cancel, leaving focus alone |
Navigation reads raw evdev keycodes, so it is layout-independent — but it also
means virtual-keyboard clients such as wtype (which invent their own keymap)
cannot drive it. That goes away with xkb support, which filtering needs anyway.
Look
Colours, font metrics and grid geometry come from the rofi theme this replaces
(gruvbox dark, a yellow selection filling the element padding, ceil(sqrt(n))
columns capped at 4, 16:9 tiles) and live in src/theme.rs. They will move to a
config file so they can't drift from the .rasi.
Requirements
A wlroots compositor advertising ext-image-copy-capture-v1,
ext-image-capture-source-v1 (with the foreign-toplevel source manager),
ext-foreign-toplevel-list-v1, wlr-layer-shell-unstable-v1 and
wp_viewporter — sway 1.11+, and in principle Hyprland, labwc and jay, though
only sway is tested. sway is also the source of truth for the window list and
for focusing, over its IPC socket.
Known upstream issue: holding per-toplevel capture sessions open makes windows blurry on fractionally scaled outputs (sway#9113). Integer scales are unaffected. It matters more once previews are live.
Roadmap
- M2 labels: real text via cosmic-text,
--hide-labelsfor an icon-only grid - M3 type-to-filter with fzf-quality fuzzy matching (and xkb keyboard input)
- M4 live previews: keep the capture sessions open and re-capture on a rate
limit,
--live all|current|none - M5 dmabuf capture, so the pixels never leave the GPU at all
Building
cargo build --release
cargo test # grid geometry