2014-01-13-211052.vim

function! s:before_get_visual()
    exec "normal! \<Esc>"
    normal! gv
endfunction

function! s:after_get_visual()
    normal! gv
endfunction

function! s:test_visual_scroll(mode)
    call g:plog('=====')

    if a:mode == 'v' | call s:before_get_visual() | endif

    let first_line   = line('w0')
    let current_line = line('.')
    let end_line     = line('w$')

    " if a:mode == 'v' | call s:after_get_visual() | endif

    call g:plog('mode   : ' . a:mode)
    call g:plog('first  : ' . first_line)
    call g:plog('cursor : ' . current_line)
    call g:plog('end    : ' . end_line)
endfunction

" Normal
nnoremap <buffer><silent> ,, :<C-u>call <SID>test_visual_scroll('n')<CR>

" Dame!
xnoremap <buffer><silent> ,1 :<C-u>call <SID>test_visual_scroll('v')<CR>
" OK!
xnoremap <buffer><silent> ,2 <Esc>:<C-u>call <SID>test_visual_scroll('v')<CR>

" How to Reproduce
" 1. :so %
" 1. gg
" 2. <C-f><C-f> (scroll ...)
" 3. ,1  ( -> dame)
" 4. ,2  ( -> ok)
"
" 1の従来の方式だとスクリーンの中心"以外"で呼ぶとずれる
" line('w$')が正しく取れないと思いきや意外と1でもとれてるので要検証...?

noremap <buffer> ,st :so %<CR>