wezterm/docs/config/lua/window/get_appearance.md

window:get_appearance()

Since: 20210814-124438-54e29167

This method returns the appearance of the window environment. The appearance can be one of the following 4 values:

• "Light" - the normal appearance, with dark text on a light background
• "Dark" - "dark mode", with predominantly dark colors and probably a lighter, lower contrasting, text color on a dark background
• "LightHighContrast" - light mode but with high contrast colors
• "DarkHighContrast" - dark mode but with high contrast colors

wezterm currently doesn't know how to interrogate the appearance on Wayland systems, and will always report "Light".

On macOS, X11 and Windows systems, wezterm is able to detect when the appearance has changed and will generate a window-config-reloaded event for each window.

This example configuration shows how you can have your color scheme automatically adjust to the current appearance:

local wezterm = require 'wezterm'

function scheme_for_appearance(appearance)
  if appearance:find("Dark") then
    return "Builtin Solarized Dark"
  else
    return "Builtin Solarized Light"
  end
end

wezterm.on("window-config-reloaded", function(window, pane)
  local overrides = window:get_config_overrides() or {}
  local appearance = window:get_appearance()
  local scheme = scheme_for_appearance(appearance)
  if overrides.color_scheme ~= scheme then
    overrides.color_scheme = scheme
    window:set_config_overrides(overrides)
  end
end)

return {
}

Wayland GNOME Appearance

The GNOME desktop environment provides the gsettings tool that can inform us of the selected appearance even in a Wayland session. We can substitute the call to window:get_appearance above with a call to the following function, which takes advantage of this:

function query_appearance_gnome()
  local success, stdout = wezterm.run_child_process(
    {"gsettings", "get", "org.gnome.desktop.interface", "gtk-theme"}
  )
  -- lowercase and remove whitespace
  stdout = stdout:lower():gsub("%s+", "")
  local mapping = {
     highcontrast = "LightHighContrast",
     highcontrastinverse = "DarkHighContrast",
     adwaita = "Light",
     ["adwaita-dark"] = "Dark"
  }
  local appearance = mapping[stdout]
  if appearance then
     return appearance
  end
  if stdout:find("dark") then
     return "Dark"
  end
  return "Light"
end

Since WezTerm will not fire a window-config-reloaded event on Wayland, you will instead need to listen on the update-right-status event, which will essentially poll for the appearance periodically:

local wezterm = require 'wezterm'

function scheme_for_appearance(appearance)
  if appearance:find("Dark") then
    return "Builtin Solarized Dark"
  else
    return "Builtin Solarized Light"
  end
end

wezterm.on("update-right-status", function(window, pane)
  local overrides = window:get_config_overrides() or {}
  local appearance = query_appearance_gnome()
  local scheme = scheme_for_appearance(appearance)
  if overrides.color_scheme ~= scheme then
    overrides.color_scheme = scheme
    window:set_config_overrides(overrides)
  end
end)

return {
}