greyline 0.1.0

A live, multi-timezone world-time desktop wallpaper for Wayland/X11.

greyline

A live world-time desktop wallpaper for Wayland/X11 — a world map with clocks for your cities, your home city highlighted, and a day/night terminator that tracks the sun. A modern recreation of the classic IBM/ThinkPad "World Time" Active Desktop.

(greyline = the ham-radio term for the day/night terminator.)

_{Shown with the optional ThinkPad wordmark (a user-supplied logo — see Licensing). The bundled default logo is Tux.}

It doesn't run a browser or a background daemon. A small Python program renders a PNG once a minute and hands it to your existing wallpaper mechanism, then exits — so it's effectively free on battery.

systemd timer (*:*:00) ─▶ greyline (renders in well under a second, then exits)
      render per output (Pillow): map + clocks + terminator
      └─▶ set wallpaper via the detected backend (sway/swww/hyprpaper/feh)

Features

• Multi-timezone clocks at each city's real location, with accurate DST via the OS IANA database (zoneinfo). 12h or 24h.
• Home city accented (dot + bold label + optional timezone-column highlight), auto-detected from your system timezone or pinned in config.
• Analytic day/night terminator, seasonally correct, with discrete civil / nautical / astronomical twilight bands.
• Vector map drawn from public-domain Natural Earth data — crisp at any resolution, fully themeable (dark, blue, or custom), with honest zig-zag timezone boundaries, a green GMT column, and a red International Date Line.
• Any resolution / multi-monitor / HiDPI — each output rendered at native pixels.
• Swappable corner logo — ships with Tux; point logo_path at your own PNG.
• Pluggable backends, auto-detected: sway, swww, hyprpaper, x11 (feh/xwallpaper).

blue theme + Tux	minimal (no logo, 12h)

Install

Nix (flake + home-manager) — recommended

# flake.nix
inputs.greyline.url = "github:cothinking-dev/greyline";

# home-manager
imports = [ inputs.greyline.homeManagerModules.default ];

services.greyline = {
  enable = true;
  backend = "sway";              # or "auto" / "swww" / "hyprpaper" / "x11"
  fontFamily = "Aporetic Sans";  # resolved via fontconfig
  settings = {
    theme = "dark";
    format = "24h";
    twilight = { bands = true; darkness = "subtle"; };
    home = { tz = "auto"; column_highlight = true; };  # "auto" = system tz
    city = [
      { name = "Kuala Lumpur"; lat = 3.14;  lon = 101.69; tz = "Asia/Kuala_Lumpur"; }
      { name = "London";       lat = 51.51; lon = -0.13;  tz = "Europe/London"; }
      { name = "New York";     lat = 40.71; lon = -74.01; tz = "America/New_York"; }
      { name = "Tokyo";        lat = 35.68; lon = 139.69; tz = "Asia/Tokyo"; }
    ];
  };
};

Try it without installing:

nix run github:cothinking-dev/greyline -- --out wt.png --res 2560x1440   # writes a PNG

pipx (other distros)

pipx install git+https://github.com/cothinking-dev/greyline   # dep: Pillow only
mkdir -p ~/.config/greyline
# edit ~/.config/greyline/config.toml (copy worldtime/default-config.toml)

# pip doesn't ship the systemd user units — grab them from the repo:
git clone https://github.com/cothinking-dev/greyline
install -Dm644 greyline/systemd/greyline.{service,timer} -t ~/.config/systemd/user/
systemctl --user daemon-reload
systemctl --user enable --now greyline.timer

Configuration

Non-Nix users edit ~/.config/greyline/config.toml; the shipped worldtime/default-config.toml is the documented template. Keys: backend, map_style (vector/raster), theme (dark/blue), format (24h/12h), logo / logo_path / logo_invert, [twilight] bands/darkness, [home] tz/column_highlight/color, and a [[city]] list (name, lat, lon, tz, optional label_side).

CLI

greyline                 # render all outputs and apply (what the timer runs)
greyline --list-outputs  # show detected backend + outputs
greyline --out wt.png --res 1920x1200   # render a PNG, no backend needed
greyline --backend swww  # force a backend

How it works

• geo.py / vectormap.py — lon/lat → pixel projection; the vector map is drawn from Natural Earth GeoJSON (supersampled for smooth coastlines).
• sun.py — subsolar point + terminator/twilight boundary latitudes.
• render.py — composites map + overlays, then draws clocks at native resolution with smart label placement (labels pick a side to avoid overlapping each other and the edges).
• backends/ — the only platform-specific code; everything else is portable.

Licensing & credits

Code is GPL-2.0-or-later. It descends from Maxim Proskurnya's GPL "World Time Wallpaper" tribute; the concept and original artwork are © IBM/Lenovo.

The default vector map uses public-domain Natural Earth data, and the default logo is Tux (Larry Ewing / GIMP) — both cleanly redistributable. The original IBM/Lenovo ThinkPad raster art and wordmark are not bundled; map_style = "raster" and the ThinkPad logo require you to supply those files yourself (see NOTICE and docs/CREDITS.md).

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