Use Escape Sequences instead of Remote Control about kitty-color-control

[kovidgoyal]

And just FYI, this is the vim/nvim color scheme I use, with suport for undercurls, and setting/removing of fg/bg colors in the terminal in pure vimscript:

l

set termguicolors
hi clear

if exists("syntax_on")
  syntax reset
endif

set background=dark
let g:colors_name = "kovid"

if has('nvim') 
    " nvim does not require ctermul and fails if it is present
    function! s:h(group, style)
    execute "highlight" a:group 
        \ "guifg="   .(has_key(a:style, "fg")    ? a:style.fg       : "NONE")
        \ "guibg="   .(has_key(a:style, "bg")    ? a:style.bg       : "NONE")
        \ "gui="     .(has_key(a:style, "styles")? a:style.styles   : "NONE")
        \ "cterm="   .(has_key(a:style, "styles")? a:style.styles   : "NONE")
        \ "guisp="   .(has_key(a:style, "ul")    ? a:style.ul       : "fg")
        \ "ctermbg=NONE"
    endfunction
else
    function! s:h(group, style)
    execute "highlight" a:group 
        \ "guifg="   .(has_key(a:style, "fg")    ? a:style.fg       : "NONE")
        \ "guibg="   .(has_key(a:style, "bg")    ? a:style.bg       : "NONE")
        \ "gui="     .(has_key(a:style, "styles")? a:style.styles   : "NONE")
        \ "cterm="   .(has_key(a:style, "styles")? a:style.styles   : "NONE")
        \ "guisp="   .(has_key(a:style, "ul")    ? a:style.ul       : "fg")
        \ "ctermul=" .(has_key(a:style, "ul")    ? a:style.ul       : "NONE")
        \ "ctermbg=NONE"
    endfunction
endif


" Color definitions
let s:bg = "#242424"
let s:bg_shaded = "#2d2d2d"
let s:bg_intense = "#000000"
let s:bg_highlight = "#ffff66"
let s:bg_fold = "#384048"
let s:cursor = "#656565"
let s:menu = "#444444"
let s:error_color = "darkred"  " cant use a hex code for this as it wont work with ctermul
let s:fg = "#e0e0e0"
let s:fg_dull = "#99968b"
let s:fg_inverted = "#000000"
let s:fg_fold = "#a0a8b0"

" General colors
if has('gui_running') 
    call s:h("Normal", {"bg": s:bg, "fg": s:fg})
else
    hi Normal NONE
    " Clear the terminal default background and foreground colors, thereby
    " improving performance by not needing to set these colors on empty cells.
    if has('nvim') 
        " nvim has no t_ti 
        call writefile(["\033]10;" . s:fg . "\007\033]11;" . s:bg . "\007"], "/dev/tty", "b")
        autocmd VimLeave * call writefile(["\033]110\007\033]111\007"], "/dev/tty", "b")
    else
        let &t_ti = &t_ti . "\033]10;" . s:fg . "\007\033]11;" . s:bg . "\007"
        let &t_te = &t_te . "\033]110\007\033]111\007"
    endif
endif
call s:h("Cursor", {"bg": s:cursor})
call s:h("CursorLine", {"bg": s:bg_shaded})
call s:h("CursorColumn", {"bg": s:bg_shaded})
call s:h("ColorColumn", {"bg": s:bg_shaded})
call s:h("NonText", {"fg": s:fg_dull, "bg": s:bg_shaded})
call s:h("StatusLine", {"fg": s:fg, "bg": s:menu})
call s:h("StatusLineNC", {"fg": s:fg_dull, "bg": s:menu})
call s:h("VertSplit", {"bg": s:menu, "fg": s:fg_dull})
call s:h("Folded", {"bg": s:bg_fold, "fg": s:fg_fold})
call s:h("Title", {"fg": s:fg, "styles": "bold"})
call s:h("Visual", {"fg": s:fg, "bg": s:menu})
call s:h("SpecialKey", {"fg": s:fg_dull, "bg": s:menu})
call s:h("MatchParen", {"fg": s:fg, "bg": s:fg_dull, "styles": "bold"})
call s:h("Pmenu", {"fg": s:fg, "bg": s:menu})
call s:h("PmenuSel", {"styles": "reverse"})
call s:h("SpellBad", {"ul": s:error_color, "styles": "undercurl"})
call s:h("Question", {'fg': '#cae682'})
call s:h("LineNr", {"fg": s:fg_dull, "bg": s:bg_intense})
call s:h("CursorLineNr", {"fg": s:fg_inverted, "bg": s:bg_highlight, "styles": "bold"})

" Plugins
call s:h("ALEErrorSign", {"bg": s:bg_intense, "fg": s:fg})
call s:h("ALEWarningSign", {"bg": s:bg_intense, "fg": s:fg})
call s:h("ALEInfoSign", {"bg": s:bg_intense, "fg": s:fg})
call s:h("ALEStyleErrorSign", {"bg": s:bg_intense, "fg": s:fg})
call s:h("ALEStyleWarningSign", {"bg": s:bg_intense, "fg": s:fg})
call s:h("ALEError", {"ul": s:error_color, "styles": "undercurl"})
call s:h("ALEWarning", {"ul": "yellow", "styles": "undercurl"})
call s:h("ALEStyleError", {"ul": "magenta", "styles": "undercurl"})
call s:h("CtrlPLinePre", {"bg": s:bg_highlight})

" Syntax highlighting
call s:h("Todo", {"fg": "orange", 'styles': "italic"})
call s:h("Constant", {"fg": "#e5786d"})
call s:h("String", {"fg": "#95e454"})
call s:h("Identifier", {"fg": "#cae682"})
call s:h("Function", {"fg": "#cae682"})
call s:h("Entity", {"fg": "#cae682"})
call s:h("Type", {"fg": "#cae682"})
call s:h("Statement", {"fg": "#8ac6f2"})
call s:h("Keyword", {"fg": "#8ac6f2"})
call s:h("PreProc", {"fg": "#e5786d"})
call s:h("Number", {"fg": "#e5786d"})
call s:h("Special", {"fg": "#e7f6da"})
call s:h("Include", {"fg": "#facf81"})
call s:h("Comment", {"fg": s:fg_dull, 'styles': "italic"})

[kovidgoyal]

look at hologram.nvim for an example of this.

[smeikx]

Using writefile seems to work in this plugin: https://github.com/ojroques/vim-oscyank/blob/5d152a9e03ca1c975c1f439456376e01561a02b5/plugin/oscyank.vim#L141

[smeikx]

This works for setting color:

call writefile(["\e]11;blue;\x07"], '/dev/fd/2', 'b')

I do not know if there is a way to get the currently set color back into nvim using escape sequences:

If a ? is given rather than a color specification, kitty will respond with the current value for the specified color.

[kovidgoyal]

You should probably use /dev/tty rather than /dev/fd/2

[smeikx]

You should probably use /dev/tty rather than /dev/fd/2

Thanks for the tip. I tried it, and it works as well. Is there any specific reason why /dev/tty is preferred?

[smeikx]

I do not know if there is a way to get the currently set color back into nvim using escape sequences:

If a ? is given rather than a color specification, kitty will respond with the current value for the specified color.

@kovidgoyal, what exactly does respond in this case mean? How does kitty put the response in the current window?
I would like to find a way to access the response through nvim, but I am struggling to to get hold of it. If this was possible, I would not need remote control at all.

[kovidgoyal]

On Sat, Feb 19, 2022 at 01:52:14PM -0800, smeikx wrote: > You should probably use /dev/tty rather than /dev/fd/2 Thanks for the tip. I tried it, and it works as well. Is there any specific reason why `/dev/tty` is preferred?

/dev/tty is *almost* always the filename of the controlling terminal for the process (technically you should use ctermid() to get the name, but I dont know of any modern unix-like system that doesnt use /dev/tty). /dev/fds/2 is usually stdout, but it is not guaranteed, think of redirects.

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[kovidgoyal]

On Sat, Feb 19, 2022 at 02:01:21PM -0800, smeikx wrote: > I do not know if there is a way to get the currently set color back into nvim using escape sequences: > > > If a ? is given rather than a color specification, kitty will respond with the current value for the specified color. @kovidgoyal, what exactly does _respond_ in this case mean? How does kitty put the response in the current window? I would like to find a way to access the response through nvim, but I am struggling to to get hold of it. If this was possible, I would not need remote control at all.

It will write the response to /dev/tty from where you can read it.

[smeikx]

A naive test:

call writefile(["\x1b]11;?\x1b\\"], '/dev/tty', 'b')
" Also write a newline; as readfile reads lines and kitty’s response does not end with a newline.
"call writefile([''], '/dev/tty', 'a')
echom readfile('/dev/tty', 'b', 1)

This freezes nvim. First I thought it freezes because of the missing newline, so I added it (commented it out again). Then I tried changing the parameters of readfile ('B' and '' instead of 'b', a higher max); using the B flag was the only combination that did not result in freezing, instead 0z was echoed.

I suspect I would have to start (asynchronously) reading from /dev/tty before writing to it (and stop afterwards), but I am not aware of any way to achieve this with regular Vimscript.
Maybe nvim’s vim.loop can provide the necessary means, maybe some kind of file watcher? I will look further into this.

[smeikx]

Just for the record, I also quickly tried the following:

local stdin = vim.loop.new_tty(0, false)
stdin:try_write('\x1b]11;blue\x1b\\')

On macOS it did change the background to blue, and made nvim freeze. On Linux it just outputs x1b]11;bluex1b\ to the terminal.

[smeikx]

I had to use literal ESC characters to make it work on Linux.

local tty = vim.loop.new_tty(0, true)
local osc = [[�]12;blue�\]]

tty:write(osc, function (err)
   assert(not err, err)
end)

This still freezes nvim on macOS though.

[smeikx]

I have also thought about directly writing to /dev/tty like this:

vim.loop.fs_open('/dev/tty', 'r+', 666, function (err, fd)
   assert(not error, error)
   print(fd)
end)

But on macOS, this crashes nvim.

[smeikx]

This might be useful: https://github.com/ojroques/nvim-osc52/blob/main/lua/osc52.lua#L69