How do I get the actual height and width of Vim?

Question

winheight() and winwidth() return the number of columns/lines in the current window. What I'm looking for is something closer to the actual height and width of the editing area, or displayed area if run in a terminal. The problem with winheight() and winwidth() is that aspect ratio calculated from these values is out of touch with the actual aspect ratio.

:echo winwidth('%') winheight('%') winwidth('%') * 1.0 / winheight('%')
104 51 2.039216

A screenshot of the buffer area is sized 936x918 pixels, giving a displayed aspect ratio of 1.019608. I think I can get the actual value by using the size of the font, but how?

This is a follow-up to How can I make Vim open help in a vertical split?. I'm trying to adapt Nobe4's solution.

Answer 1

104 columns / 51 lines = 2.04

Your calculation is skewed because the aspect ratio of each cell is vertical.

For example on Terminal.app, with 23pt font and default character spacing, each terminal cell have a width of 7px and a height of 15px for a total of 728x765px:

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You cannot retrieve the font size from within Vim without invoking external commands or a way of communicating with the terminal, which can become pretty heavy. Obviously, this is different in Gvim thanks to 'guifont'.

If you manage to do it, still you need a way to deduct the size of a cell which may vary depending on the terminal program if there is no standard. I only checked iTerm 2 which luckily have the same result.

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Therefore I would opt for a static solution. I grafted the minimum width check to this snippet you could place in plugin/help.vim:

function! Help(...)
  let l:topic = a:0 ? a:1 : ''
  if winwidth('%') >= 160 " Minimum width
    execute 'vertical botright help' l:topic
    execute 'vertical resize 78'
  else
    execute 'botright help' l:topic
  endif
endfunction

" Use :H to open a vertical or horizontal help split
command! -complete=help -nargs=? H call Help(<f-args>)

If the window is large enough to keep 80 columns of the current buffer, a narrow help split is opened on the right, otherwise the split is opened below. You can customize the split direction with :vertical.