Support dark and light themes and syncing theme to system setting, a la window decorations

[sloane-shark]

Several other popular terminals support the ability to configure independent themes for dark and light mode, which will then be automatically selected according to the system's dark or light mode setting. Ghostty already supports syncing the light or dark value of the window decorations with the system setting, so I imagine we could leverage the same logic for themes.

For a little bikeshedding, since themes are just configurations, I think it would probably make sense to introduce light-config-file and dark-config-file for arbitrary configuration files that are loaded and unloaded according to the system setting. This would allow adjusting other settings if desired, such as fonts or transparency.

[rockorager]

Contour has written a VT extension to notify applications using escape sequences that a color scheme change occurred. Would be good to include this reporting as part of this feature

Reference

[mitchellh]

Contour has written a VT extension to notify applications using escape sequences that a color scheme change occurred. Would be good to include this reporting as part of this feature

I would like to keep these separate and focus this issue on the process of configuring Ghostty with theme-specific configurations. I agree with supporting this once it has settled a bit though.

[mitchellh]

Sharing some prior thinking I've had on this. None of this is set in stone, its not a mandate. Just thoughts.

From a design perspective, I think its important that Ghostty retains the property that the CLI arguments and configuration format is isomorphic. I've personally always enjoyed it when software has had that property, because its easy to move stuff around between files and scripts. For those unaware, every Ghostty configuration key is also a valid CLI flag, and the format is identical. The config lines just don't have the -- prefix a CLI flag has.

So, I'd like to retain that property.

I think the suggestion OP has around light-config-file and dark-config-file is not bad, because it does retain that to some extent, but one issue is that you can then only set themed configurations within files, not directly on the CLI.

An approach I was trying to consider was the ability to annotate any config key with a condition in which it is active. For example: background = FF0000 [theme=dark]. This is just an example, not literal proposed syntax. Then in the CLI you could do --background="FF0000 [theme=dark]". I don't love that syntax but the idea I think is more important. This approach would also still enable the dark/light config file because you could do config-file = my-dark-config [theme=dark].

The condition proposal also would let us introduce other conditions. For example, I share my identical Ghostty config between macOS and Linux, and I'd love to have some Linux-specific keybindings. It'd be nice to do keybind = something [os=linux] or whatever.

The condition proposal could also easily extend into AND, OR conditions, although there is no need to introduce that complexity today. I'm merely pointing out the framework allows for it.

🚲🏠 (Bikeshed): We could also bake the condition into the key, i.e. background[theme=dark] = FF0000. This becomes clunkier on the CLI because you'd have to quote the entire thing including the --. Perhaps there are other approaches.

[erf]

Regarding themes, Wezterm ships 700+ iTerm2 themes, is this something Ghostty will do too (or can be inspired by) ?

[mitchellh]

Regarding themes, Wezterm ships 700+ iTerm2 themes, is this something Ghostty will do too (or can be inspired by) ?

Again, I'd like to not make that a focus of this issue, but we could definitely ship those as part of the resources directory. There are already over 250 Ghostty themes available here: https://github.com/mbadolato/iTerm2-Color-Schemes (Ghostty being one of the formats available)

[mitchellh]

Note with #942 we now have built-in themes set with theme. (Not merged at the time of writing this comment because I'm waiting on an upstream PR but I expect that'll happen soon) This configuration will fit very nicely with the ideas proposed in this issue.

[sloane-shark]

i've been meaning to sit down and hash out some alternate syntax proposals for this, but have been busy. re your latest bikeshed method, i'm not sure we WOULD have to quote so aggressively, at least in all cases... i think most shell parsers would let us get away with something like --[mode=dark]theme=my-theme on the CLI, we would just have to implement the splitting by hand. i think that might already be what is done, anyway?

[mitchellh]

i think that might already be what is done, anyway?

Yep!

Happy to hear more bikeshed ideas, I think I've enumerated my constraints/desires clearly above but feel free to ask any Qs.

[adamcstephens]

I've used external scripts with kitty to provide light/dark toggling. Kitty has a subcommand to set individual colors, or it can load them from a file (e.g. a theme file).

The subcommand even has other options for targeting all windows, how new windows are handled, etc. For my purposes I've been happy with just sending the theme change to all terminals.

Adding concepts for light and dark are nice, but maybe just on-the-fly loading of a theme file could go a long way towards enabling that.

Usage: kitten @ set-colors COLOR_OR_FILE ...

Set the terminal colors for the specified windows/tabs (defaults to active
window). You can either specify the path to a conf file (in the same format as
kitty.conf) to read the colors from or you can specify individual colors, for
example::


kitten @ set-colors foreground=red background=white

[gagbo]

Adding concepts for light and dark are nice, but maybe just on-the-fly loading of a theme file could go a long way towards enabling that.

I think I’d prefer that as well, I don’t know how easier/harder it would be to configure. My sole usecase for "quick theme switching" is actually runtime cursor color switching. When I switch my editor from light to dark theme, I’d like to have a quick command (shelling out is ok) to change the cursor color from dark to bright.

(Bear with my slow typing in the small demo)

Enregistrement.de.l.ecran.2024-05-14.a.12.02.36.mov

[roguesherlock]

Adding concepts for light and dark are nice, but maybe just on-the-fly loading of a theme file could go a long way towards enabling that.

I think I’d prefer that as well, I don’t know how easier/harder it would be to configure. My sole usecase for "quick theme switching" is actually runtime cursor color switching. When I switch my editor from light to dark theme, I’d like to have a quick command (shelling out is ok) to change the cursor color from dark to bright.

(Bear with my slow typing in the small demo)

Enregistrement.de.l.ecran.2024-05-14.a.12.02.36.mov

I have this autocommand in my neovim config which switches the ghostty theme. I just have to then press cmd+shift+, to reload. Thought I'd share in case it's helpful until we have proper theme syncing,

vim.api.nvim_create_autocmd("ColorScheme", {
  pattern = "*",
  callback = function()
    if vim.o.background == "light" then
      if term == "xterm-kitty" then
        vim.fn.system("kitty +kitten themes " .. M.terminal_theme_light)
      elseif term == "xterm-ghostty" then
        vim.fn.system(
          "sed -i'.bak' 's/theme = .*/theme = "
            .. M.terminal_theme_light
            .. "/' (readlink ~/.config/ghostty/config)"
        )
      end
    elseif vim.o.background == "dark" then
      if term == "xterm-kitty" then
        vim.fn.system("kitty +kitten themes " .. M.terminal_theme_dark)
      elseif term == "xterm-ghostty" then
        vim.fn.system(
          "sed -i'.bak' 's/theme = .*/theme = "
            .. M.terminal_theme_dark
            .. "/' (readlink ~/.config/ghostty/config)"
        )
      end
    end
  end
})