Fix g:lsp_preview_max_width for Neovim

[thomasfaingnaert]

In response to #416 (comment).

I decided to try a different approach. Rather than hard wrapping the text using gq and 'textwidth', I softwrap by setting the maxwidth.
The only problem with this, is that we need to explicitly calculate the height of the floating window (as far as I can tell, anyway; if someone know a way where we can avoid this, let me know).

To accomplish this, I iterate over all lines and sum ceil(line_width / max_width) (i.e. the number of "virtual" lines needed to show this line).

[clason]

Yes, this works nicely, thank you! (Arguably, adjusting the height of the floating window would be the right thing to do even if max_width isn't set.)

[clason]

One nitpick: max_width seems also to be taken as min_width, i.e., shorter hover texts are padded to max_width.

Something like

    let l:maxwidth = max(map(getline(1, '$'), 'strdisplaywidth(v:val)'))  
    if g:lsp_preview_max_width > 0
      let l:bufferlines = 0
      let l:maxwidth = min([g:lsp_preview_max_width,l:maxwidth])

      " Determine, for each line, how many "virtual" lines it spans, and add
      " these together for all lines in the buffer
      for l:line in getline(1, '$')
        let l:num_lines = str2nr(string(ceil(strdisplaywidth(l:line) * 1.0 / g:lsp_preview_max_width)))
        let l:bufferlines += max([l:num_lines, 1])
      endfor
    else
      let l:bufferlines = line('$')
    endif

should do the trick.

[thomasfaingnaert]

@clason
Fixed, thanks.

[thomasfaingnaert]

@clason Can I merge this in or does it still not work perfectly?

[clason]

Yes, please! (Adjusting the height without max_width is a separate issue; this is a working fix for the issue I raised in my comment.)