Vim highlight every Nth line numbering?

Question

My line numberings in Vim are blue (background) and white (foreground) but this is not very clearly especially for large files.

I would like to have every fifth line numbers background in darkblue and every tenth line numbers foreground in red, so that one can distinguish between 5 and 10 lines of code easily without counting or having to focus at the line numbering.

How can I make this happen? Unfortunately I did not find any plugin doing this..

Answer 1

You can use my DynamicSigns plugin. It defines a SignExpression command, that works similar to the foldexpression. In your case, you could simply do:

:SignExpression v:lnum%10==0?'Line1':v:lnum%5==0?'Line2':''

Advantage of using my plugin is, it takes care of adjusting the line numbers automatically, when you add or delete lines. Note: depending on the size of your file, this might slow down Vim. But this is a problem, many sign plugins have in common, since there is no VimL API for accessing signs.

Answer 2

You cannot make different hl(highlighting) on the line number column. You can somehow highlight the text in the line however. But I guess this is not what you are looking for, you just want to see some flag/highlighting on the line number column. Then the sign might be the closest to your requirement.

source this codes: (I just randomly picked color, you can adjust them as you like)

hi FifGroup term=bold ctermfg=red 
hi TenGroup term=bold ctermbg=darkgreen 
sign define fifth texthl=FifGroup text=-> 
sign define tenth texthl=TenGroup text=>>
fun! PlaceLineSign()
    for i in range(1+line('$'))
        if i =~ '5$'
            execute 'sign place '.i.' line='.i.' name=fifth buffer='.bufnr('%')
        endif
        if i =~ '0$' && i>0
            execute 'sign place '.i.' line='.i.' name=tenth buffer='.bufnr('%')
        endif
    endfor

endf

fun! RemoveLineSign()
    sign unplace *
endf

nnoremap <F6> <c-u>:call PlaceLineSign()<cr>
nnoremap <F7> <c-u>:call RemoveLineSign()<cr>

then you can press <f6> to display those flag, and <F7> to hide them.

Note, there is one problem with "sign", if you displayed the signs, and change the line numbers, i.e. removed/added new lines, the "sign"s won't change correspondingly. But hide and display again should go.

It looks like:

Answer 3

I'm also thinking about the same thing but unfortunately there's no easy way to do it (unless using sign support as other answers suggested, at the cost of slowing down).

The best close thing native to vim is LineNrAbove/Below. However, it's defined in vim source itself: https://github.com/vim/vim/blob/f3fa18468c0adc4fa645f7c394d7a6d14d3d4352/src/drawline.c#L1156-L1167; It should be easy to extend to highlight groups like every k-th relative line but it I don't think in the foreseeable future that it would be included in vim. I believe this is the only usable option because evaluating is done in the vim core which is fast than doing so at vim script.