[mini.misc] org.freedesktop.appearance

[wroyca]

Hello o/

This is my take on implementing org.freedesktop.appearance.color-scheme with interrupts, as discussed in this GitHub issue. I figured this might be useful to others.

One interesting aspect of the XDG Desktop Portal is the color accent and contrast keys, which would integrate nicely with mini.hues. I intend to update this once they are integrated into my desktop, potentially in Fedora 41.

In any case:

--- Set up org.freedesktop.appearance.
---
--- The org.freedesktop.appearance.color-scheme key got standardized in the XDG
--- desktop portal  specification across all DEs. This make it possible on both
--- X11 and Wayland to be notified at runtime as soon as the dark mode
--- preference changes.
---
--- Currently, the Settings interface provides the following keys:
---
--- - org.freedesktop.appearance color-scheme
---   Indicates the system’s preferred color scheme.
---
--- - org.freedesktop.appearance accent-color (ddd)
---   Indicates the system’s preferred accent color as a tuple of RGB values
---   in the sRGB color space, in the range [0, 1]. Out-of-range RGB values
---   should be treated as an unset accent color.
---
--- - org.freedesktop.appearance contrast (u)
---   Indicates the system’s preferred contrast level.
---
--- https://flatpak.github.io/xdg-desktop-portal/docs/doc-org.freedesktop.portal.Settings.html
--- https://github.com/flatpak/xdg-desktop-portal/issues/629
---
--- What it does:
--- - Retrieves and interprets information from org.freedesktop.appearance
---   interface.
---
--- - Extracts color-scheme key to determine current color scheme preference
---   set by user.

--- - Executes gdbus in background to continuously monitor changes to color
---   scheme preference. FYI monitoring uses interrupts instead of polling.
---
--- - Immediately synchronizes Neovim’s "background" option with detected
---   preference.
---
MiniMisc.setup_appearance_sync = function()
  -- org.freedesktop.appearance color-scheme
  --
  -- Supported values are:
  -- - 0: No preference
  -- - 1: Prefer dark appearance
  -- - 2: Prefer light appearance
  local function parse_color_scheme(line)
    local v = tonumber(line:match("uint32 (%d+)"))
    if v == nil then return end
    vim.o.background = (v == 2 or v == 0) and "light" or "dark"
  end

  vim.fn.jobstart(
    "gdbus monitor --session --dest org.freedesktop.portal.Desktop --object-path /org/freedesktop/portal/desktop",
    {
      on_stdout = function (_, data)
        -- Process stdout data. Note that it come in multiple chunks. Join all
        -- chunks into a single line.
        local line = table.concat(data)
        
        -- org.freedesktop.appearance color-scheme
        if string.find(line, "color%-scheme") then
          parse_color_scheme(line)
        end
      end
    }
  )

  -- Apply the correct background based on the user’s preference (dark or
  -- light) when Neovim starts. This should be done before we begin monitoring
  -- changes.
  parse_color_scheme(
    vim.fn.system(
      "gdbus call -t 1 --session --dest=org.freedesktop.portal.Desktop --object-path=/org/freedesktop/portal/desktop --method=org.freedesktop.portal.Settings.Read org.freedesktop.appearance color-scheme"
    )
  )
end

[echasnovski]

Nice!

I'd probably refactor the parse_color_scheme to be like this:

  local function parse_color_scheme(line)
    local v = line:match("uint32 (%d+)")
    if v == nil then return end
    vim.o.background = (v == '1' or v == '0') and 'light' or 'dark'
  end

[wroyca]

Done. Thanks! If you have more tips, go ahead! 🥳

[echasnovski]

Well, I don't really see the point of the whole while #lines > 1 do local line = table.remove(lines, 1); .... As local lines = {""} is defined inside function body, it does not persist across on_stdout calls.

What I'd probably do is create local feed = {} before first vim.fn.system() call and try something like this:

on_stdout = function(_, data) table.insert(feed, data) end,
on_exit = function()
  local lines = vim.split(table.concat(feed, ''), '\n')
  -- Do the magic
end

[wroyca]

Oh, nice catch. This was initially for debugging :)