wlgrid described the shape of the thing rather than what it is for, and
the shape is the least interesting part now that it doesn't focus
anything: it shows you what is running and reports which one you pointed
at. wl-pick says that.
The wl- prefix rather than wlr- is deliberate. The capture path is
entirely upstream ext- protocols (ext-image-copy-capture,
ext-image-capture-source, ext-foreign-toplevel-list); the only
wlroots-flavoured piece is layer-shell, which KDE, niri and labwc
implement too. What actually keeps this from running on other
compositors is the sway IPC dependency, not wlroots, so wlr- would
promise a portability that isn't there. Hyphenated because the ecosystem
hyphenates when the suffix is a real word — wl-clipboard, wl-mirror,
wl-screenrec — and reserves the smushed form for coinages like wlsunset.
Also renames the layer-shell namespace and the memfd labels, which show
up in compositor debugging.
"title · app" centred under each thumbnail, in the same font the rofi
theme used (Berkeley Mono at pango's "small"), with the selected tile's
label inverted onto the yellow the way rofi's element background did.
Long titles are ellipsised to the cell width.
Text comes from cosmic-text, which brings real shaping. The catch is
cost: building a font system and rasterising the first glyphs takes
~55ms, nearly doubling a 65ms startup. But the capture phase is ~55ms of
sitting blocked while the compositor copies pixels, so labels are shaped
on a worker thread started before the captures and joined after them.
The measured labels phase is now 0.0ms — it costs nothing in wall clock.
Two thirds of that font cost was FontSystem::new() scanning all 1793
system faces, which even new_with_fonts() does. So the database is built
by hand: the user's own font directories first, since they are small,
and the full system scan only when the family isn't found there. An
unknown family still resolves, because that fallback is exactly the
system scan (verified: --font "No Such Font" renders in Noto).
--hide-labels restores the icon-only grid, and --font/--font-size make
the family and size settable. Adds a test that a label actually puts
pixels on the surface, one for ellipsising, and one pinning the label row
into the element geometry.
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.
Milad Alizadeh