Milad Alizadeh
487acb8b6a
Colours, border and thumbnail size come from ~/.config/wl-pick/config now, since ten more flags would have made a keybinding unreadable — the split the rofi setup this replaces already used: look in a file, behaviour on the command line. Flat `key = value` lines, so no TOML dependency for something with nothing to nest, and a flag still beats the file. Sizes take sway's units. `600px` is absolute; `70ppt` is a percentage of the display the grid appears on, resolved on every run rather than baked in, so one config suits monitors of different sizes. That needed the overlay to know which display it is on, so it now asks sway for the focused one and maps there explicitly, at that display's scale, instead of letting the compositor choose and taking the largest scale in use — which was wrong on any mixed-DPI setup. tile-width and tile-height are maxima. Given only a width, the height follows the display's aspect: a 16:9 cell, inherited from a rofi theme written for a landscape screen, wasted about half of every cell on a portrait monitor. And if the grid would outgrow the display, tiles now shrink together, keeping their shape, so thirty windows produce small tiles rather than a surface larger than the screen. The surface is capped at the display as a backstop, because on a small screen the padding and label rows can exceed it no matter how small the tiles get. Two bugs the tests caught while writing this: - Stripping comments at the first '#' ate colour values, so `selection = #d79921 # note` parsed as empty. A comment is now a '#' followed by whitespace or end of line; a colour is '#' then a hex digit, so the two cannot collide. - Twelve tiles at the old fixed size fit a 1280x800 screen, so the first version of the shrink test proved nothing. It now uses numbers that genuinely overflow. Also: failing to reach sway said only "No such file or directory", which tells a first-time user nothing; it now names sway and what it wanted.
244 lines
10 KiB
Markdown
244 lines
10 KiB
Markdown
# wl-pick
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A window switcher for wlroots compositors: a grid overlay of **live** window
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previews that looks like a rofi theme, and tells you which one you picked.
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It replaces a `wlthumbs | rofi` pipeline, and doubles as a screencast source
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picker for the desktop portal. The difference is that no thumbnails
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exist: each window is captured straight into a `wl_shm` buffer that is handed to
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its own `wl_subsurface`, and `wp_viewporter` tells the compositor which rectangle
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to scale it into. There is no image encoding, no scaler, and no full-resolution
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bitmap in this process — which is also why it appears in about 60 ms and holds
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~18 MB of RSS however many windows are open.
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```
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sway-tree 0.6ms window list + con_ids over sway IPC
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toplevels 0.2ms ext-foreign-toplevel-list handles
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constraints 1.5ms every capture session's buffer size, in one roundtrip
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capture 52.5ms 8 windows, all frames in flight at once
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labels 0.0ms shaped on a worker thread while the captures ran
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mapped 4.9ms layer surface + subsurfaces on screen
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```
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The capture phase is the compositor reading full-resolution window pixels out of
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the GPU. It is bandwidth-bound (~1.1 GB/s here) and unaffected by how large the
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thumbnails are — which also makes it a free window to do other work in. Loading
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a font and rasterising its first glyphs costs ~20ms, so labels are shaped on a
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worker thread started before the captures and joined after them, and cost
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nothing in wall clock.
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## Status
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Working: a labelled grid of live previews with keyboard navigation. Type-to-filter
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is the one thing the rofi version had that this doesn't — see the roadmap.
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## Usage
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```
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wl-pick [--format tsv|json|portal] [--live all|current|none] [--fps N]
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[--no-outputs] [--hide-labels] [--font FAMILY] [--font-size PX]
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[--timeout SECS] [--verbose]
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```
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- `--format tsv|json|portal` how to report the pick (default `tsv`)
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- `--live all|current|none` which tiles keep updating (default `all`; displays
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are always a single snapshot)
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- `--fps N` cap on live updates per tile per second (default 12)
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- `--no-outputs` windows only; displays are included as tiles by default
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- `--hide-labels` draws an icon-only grid
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- `--font FAMILY` label font family (default: the system monospace font)
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- `--font-size PX` label size in logical px
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- `--config PATH` config file (default `~/.config/wl-pick/config`)
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- `--timeout SECS` exits after a deadline, in case the keyboard grab ever traps
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you
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- `--verbose` phase timings, the tile list, and capture stats
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wl-pick is a chooser: the pick goes to stdout, nothing does if you cancel, and
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the exit status is 0 for a pick and 1 for a cancel. It never acts on the choice —
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it has no idea what you want to do with it. Focusing on sway looks like this:
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```sh
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#!/usr/bin/env bash
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# ~/.local/bin/winmenu, bound to $mod+Tab
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IFS=$'\t' read -r type id toplevel app title < <(wl-pick) || exit 0
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case $type in
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window) swaymsg "[con_id=$id] focus" ;;
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output) swaymsg "focus output $id" ;;
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esac
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```
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Windows only, as a one-liner:
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```sh
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swaymsg "[con_id=$(wl-pick --no-outputs | cut -f2)] focus"
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```
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Three formats, because the identifiers different consumers need differ:
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| `--format` | output |
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|---|---|
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| `tsv` (default) | `TYPE⇥ID⇥TOPLEVEL_ID⇥APP⇥TITLE` — `ID` is the sway `con_id`, or the output name for a display; `TOPLEVEL_ID` is the ext-foreign-toplevel-list-v1 identifier that `grim -T` and the portal capture by |
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| `json` | the same record with every key always present, for `jq` |
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| `portal` | `Monitor: NAME` or `Window: TOPLEVEL_ID` |
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`portal` is exactly what xdg-desktop-portal-wlr's `simple` chooser reads, so
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wl-pick can be the picker for `getDisplayMedia` and friends — with live previews
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of both windows and displays:
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```ini
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[screencast]
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chooser_type=simple
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chooser_cmd=wl-pick --format portal
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```
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| key | |
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|---|---|
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| `→` `←` / `l` `h` / `Tab` `Shift+Tab` | next / previous tile |
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| `↓` `↑` / `j` `k` | move a row |
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| `Home` `End` | first / last |
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| `Enter` | pick the selection |
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| `Escape` / `q` | cancel |
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| click | pick that tile |
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| scroll | next / previous tile |
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Hovering deliberately does not move the selection — the keyboard keeps it, and a
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click acts on whatever is under the cursor. Clicking the margin, a gap, or an
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empty cell of a ragged last row does nothing. Tiles are subsurfaces, so a click
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on a thumbnail identifies its tile by surface; only clicks on the chrome around
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them need hit-testing.
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Navigation reads raw evdev keycodes, so it is layout-independent — but it also
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means virtual-keyboard clients such as `wtype` (which invent their own keymap)
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cannot drive it. That goes away with xkb support, which filtering needs anyway.
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## Live previews
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Capture sessions stay open, so a tile can be refreshed. Three things keep that
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from being expensive:
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- **It is damage-driven.** After a session's first frame the compositor only
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produces another once the window content changes, so a request left
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outstanding on an idle window costs nothing. Measured over 4s with one
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animating window out of ten: `52,52,1,1,1,1,1,1,13,1` frames — the static
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windows delivered exactly their first frame and nothing more.
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- **Frame callbacks are the clock.** Re-captures are driven by the overlay's own
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`wl_surface.frame` callbacks, so they stop when it isn't being presented, and
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`--fps` throttles per tile on top of that (12 fps measured as 12.1).
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- **Two buffers per window, alternating.** A capture must not write into a buffer
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the compositor is reading, so each window gets two and `wl_buffer.release`
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decides which is free. Note that release is the entire contract: with `wl_shm`
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the compositor copies the pixels out at commit and hands the buffer straight
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back, so the slot on screen is usually free too — waiting for it to stop being
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displayed instead deadlocks after two frames.
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The cost is memory and bandwidth: two full-resolution buffers per window (138 MB
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of shm for eight windows and a display here, against 83 MB with `--live none`)
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and a readback per refreshed frame. `--live current` refreshes only the selected tile,
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which is much cheaper and still reads as alive.
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## Config
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`~/.config/wl-pick/config`, or `--config PATH`. Flat `key = value` lines with
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`#` comments, everything optional, and a flag always beats the file. No TOML
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dependency, because there is nothing to nest.
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```ini
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background = #282828 # the grid's backdrop
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foreground = #ebdbb2 # label text
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selection = #d79921 # the highlighted tile
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selection-text = #282828 # its label
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border = #d79921
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border-width = 2px
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tile-width = 18ppt # largest a thumbnail may be
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tile-height = 20ppt # defaults to the display's aspect
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max-columns = 4
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font = monospace
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font-size = 13.3
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labels = yes
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outputs = yes
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live = all
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fps = 12
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format = tsv
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```
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Sizes take sway's units: `600px` is absolute, `70ppt` a percentage — and the
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percentage resolves against **the display the grid actually appears on**, every
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time it runs. On a mixed setup one file gives 18% of a 1280-wide laptop panel and
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18% of a 3840-wide monitor, instead of a pixel count that suits one and looks
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wrong on the other. The overlay is mapped explicitly on that display, at that
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display's scale, so mixed-DPI renders crisply either way.
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`tile-width` and `tile-height` are maxima for the thumbnail cell. Give only the
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width and the height follows the display's aspect, which is roughly the shape of
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the windows on it — a 16:9 cell wastes about half its area on a portrait monitor.
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If the grid would outgrow the display, tiles shrink together and keep their
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shape, so thirty windows give small tiles rather than a surface larger than the
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screen.
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## Look
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The defaults come from the rofi theme this replaces: gruvbox dark, a yellow
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selection filling the element padding, `ceil(sqrt(n))` columns capped at 4,
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`title · app` centred underneath. Padding, gaps and margins are still fixed, in
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`src/theme.rs`.
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The label font defaults to the system monospace font — whatever `fc-match
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monospace` answers, which is what the rest of the desktop uses. (cosmic-text's
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own generic resolves through a built-in preference that is usually not
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installed, and then lands on an arbitrary face, so it is asked directly
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instead; if fontconfig isn't available, a short list of common distribution
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defaults is tried.) `--font` names a family instead, and `--verbose` reports
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which family the labels were actually shaped with.
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Naming a family scans your own font directories first because they are small;
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the full system scan (~37ms) happens only if it isn't found there. An unknown
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family falls back to whatever cosmic-text picks rather than failing. Long titles
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are ellipsised to the cell.
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## Requirements
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A wlroots compositor advertising `ext-image-copy-capture-v1`,
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`ext-image-capture-source-v1` (with the foreign-toplevel source manager),
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`ext-foreign-toplevel-list-v1`, `wlr-layer-shell-unstable-v1` and
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`wp_viewporter` — sway 1.11+, and in principle Hyprland, labwc and jay, though
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only sway is tested. sway is also the source of truth for the window list, over
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its IPC socket, which is the one thing that would need replacing to run
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elsewhere (`ext-foreign-toplevel-list-v1` already reports app id and title).
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Known upstream issue: holding per-toplevel capture sessions open makes windows
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blurry on **fractionally scaled** outputs
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([sway#9113](https://github.com/swaywm/sway/issues/9113)). Integer scales are
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unaffected. It matters more once previews are live.
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## Roadmap
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- type-to-filter with fzf-quality fuzzy matching (and the xkb keyboard input it
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needs, which would also let virtual-keyboard clients drive the overlay)
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- dmabuf capture, so the pixels never leave the GPU at all — and live previews
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stop costing a readback per frame
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## Source layout
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```
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main.rs orchestration: list, capture, map, report the pick
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cli.rs flags, defaults, and the help text that documents them
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sway.rs the window list and display names, over sway's IPC socket
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target.rs what a tile stands for, and the three output formats
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app.rs the Wayland client state every event dispatches into
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capture.rs capture sessions, their buffers, and the live clock
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overlay.rs the layer surface, the drawing, and the keyboard
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theme.rs colours, grid geometry, aspect fitting
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text.rs label shaping on a worker thread
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shm.rs memfd allocation and the ARGB painter
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```
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## Building
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```
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cargo build --release
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cargo test # grid geometry and hit-testing, ellipsising, output
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# formats, glyph output
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```
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