Remap Up and Down arrows to gj-gk in vim input mode without using <c-o>?

Question

I have mapped my arrows keys to move in a visual-line mode, leaving the hjkl keys for normal, logic line movement:

" Visual movement with the arrows and End-Home 
nnoremap <Down> gj
nnoremap <Up> gk
vnoremap <Down> gj
vnoremap <Up> gk
inoremap <Down> <C-o>gj
inoremap <Up> <C-o>gk
inoremap <Home> <C-o>g<Home>
inoremap <End>  <C-o>g<End>

This works, but for a minor problem. I have a bit of code in my status line to change color between input mode and normal mode, like this:

if version >= 700
  highlight statusLine cterm=bold ctermfg=black ctermbg=red
  au InsertLeave * highlight StatusLine cterm=bold ctermfg=black ctermbg=red gui=bold guifg=black guibg=red
  au InsertEnter * highlight StatusLine cterm=bold ctermfg=black ctermbg=green   gui=bold guifg=black guibg=green
endif

...and I noticed now (on a machine slower than the one I have at home) that every time I press one of the arrows, the temporary mode switch of <ctrl>o (at least, I think) make the status line flash rapidly red then green again.

It is possible to redefine the keys to avoid the temporary jump to normal mode?

Answer 1

I have two ideas, but both are quite complex:

1. Use :inoremap <expr> and perform the cursor repositioning with :call cursor() yourself. The downside is that you have to do the calculation which wrapped column is directly over / under the cursor.
2. Use :inoremap <expr> to wrap the <C-o>gj command in :set eventignore+=InsertLeave,InsertEnter before and option restore afterwards, like this:

function! IgnoreOn( motion )
    set eventignore+=InsertLeave,InsertEnter
    return "\<C-o>" . a:motion
endfunction
function! IgnoreOff()
    set eventignore-=InsertLeave,InsertEnter
    return "\<Left>\<Right>" | " Workaround for missing screen update.
endfunction
inoremap <expr> <SID>IgnoreOff IgnoreOff()
inoremap <expr> <SID>IgnoredDown IgnoreOn('gj')
inoremap <script> <Down> <SID>IgnoredDown<SID>IgnoreOff

Answer 2

My solution is based on Igno's suggestions, but does not require excessive mouse movement.

autocmd! InsertEnter * set eventignore-=InsertLeave
function! s:UpDown(keys)
  set eventignore+=InsertLeave
  return "\<C-O>".a:keys
endfunction
inoremap <expr> <DOWN> <SID>UpDown('gj')
inoremap <expr> <Up> <SID>UpDown('gk')