musteresel's blog

Kakoune change colorscheme with mode and clipboard integration


tagged: kakoune, linux, editor

I’m currently trying out Kakoune as editor instead of Emacs. I won’t go into details about it - that’s easily findable on its website - but will cut straight to the point: It is a modal editor, similar to Vim. So instead of using key combinations during writing there is an “insert” mode, in which one can insert text, and a “normal” mode, which is used for commands. (There are more modes of course; but those two are the most important right now.)

An issue I always had with Vim is that I never know which mode I’m currently in. People said I’d get used to it, but I didn’t, so for Kakoune I wanted to make sure I have a strong visual clue of the current mode. Changing colorschemes - especially from a dark to a light one - is a pretty strong visual clue:

hook global WinCreate '.*' %{
  colorscheme window-solarized-dark
  hook window ModeChange 'push:.*:insert' 'colorscheme window-solarized-light'
  hook window ModeChange 'push:insert:.*' 'colorscheme window-solarized-dark'
  hook window ModeChange 'pop:insert:.*' 'colorscheme window-solarized-dark'
  hook window ModeChange 'pop:.*:insert' 'colorscheme window-solarized-light'

This is a hook (with global scope) which executes on the creation of any window. It sets a colorscheme “window-solarized-dark” (under the assumption that the initial mode of a window is not insert mode) and then goes on to install 4 hooks in the scope of the just created window. These hooks execute when there is a mode change in the current window, and set a colorscheme “window-solarized-light” whenever the mode is changed to insert mode.

Initially I thought 2 hooks would do: One for entering insert mode and one for leaving insert mode. But since modes in Kakoune are on a stack, you can enter insert mode, then push a new mode on the stack (and thus temporarily switching to that mode) and then pop back into insert mode. That’s why there’s 4 cases, in the same order as the hooks above:

The last thing missing is the colorscheme: I couldn’t just use any of the provided colorschemes, because they have code like this:

face global Whitespace <some-color>

They set the faces in the global scope. But I only want to change the colorscheme in a single window, thus I changed the colorschemes (in my case the solarized colorschemes which come by default with kakoune) to install the faces in window scope:

face window Whitespace <some-color>

And then I have a very strong visual clue in which mode I’m in!

As an added bonus, here’s how I integrated the clipboard into Kakoune:

define-command yank-clipboard %{
  execute-keys -draft '<a-|>xclip -in -selection clipboard >&- 2>&-<ret>'
define-command paste-clipboard %{
  execute-keys -draft '!xclip -out - -selection clipboard 0>&- 2>&-<ret>'

yank-clipboard pipes the (Kakoune) selection(s) to xclip, which reads from stdin into the (X) selection “clipboard”. Additionally, due to how xclip works, I close it’s stderr and stdout.

paste-clipboard reads from the pipe connected to stdout of xclip, which reads out of the (X) selection “clipboard”. To avoid xclip hanging I close its stdin and stderr.