Keep X-rows below current cursor position if fewer than Y-rows are left

Question

I recently started using Vim to write my notes after moving away from VS Codium for this. I'm really enjoying the speed and the ability to navigate keyboard only, but there is one thing that is slightly annoying and I was wondering if there is already a solution.

I understand that scrolloff will keep space above and below a cursor but this is when scrolling through a file. It doesn't work when typing. I understand that zz will recenter the file on the cursor position and that Ctrl-e moves down one line. So when I'm writing and I'm reaching the end of the file, I could zz or Ctrl-e to adjust the position. However, I was wondering if there was a way to automate this, something like:

if (eof - :.) < 5
  zz

Or something along those lines?

Answer 1

You use autocommands to invoke <C-E> when the cursor gets within &scrolloff of the bottom of the window.

Here's an adaptation of my answer to a similar question that implements the above:

augroup ScrollOffAtEnd
  autocmd!
  autocmd CursorMoved * call ScrollOffAtEnd(0)
  autocmd TextChangedI * call ScrollOffAtEnd(1)
augroup END

function ScrollOffAtEnd(insert_mode) abort
  while winheight(0) > &scrolloff && winline() > winheight(0) - &scrolloff
    let at_end = a:insert_mode ? getcursorcharpos()[2] > len(getline('.')) : 0
    execute "normal!\<C-E>"

    " Fix position of cursor when 'wrap' occurs
    if at_end
      let cursor_pos = getcursorcharpos()
      let cursor_pos[2] = cursor_pos[2] + 1
      call setcursorcharpos(cursor_pos[1:])
    endif
  endwhile
endfunction