Improve hover popup behavior

autoload/fern.vim

@@ -47,6 +47,7 @@ call s:Config.config(expand('<sfile>:p'), {
       \ 'comparators': {},
       \ 'drawer_width': 30,
       \ 'drawer_keep': v:false,
+      \ 'drawer_hover_popup_delay': 0,
       \ 'mark_symbol': '*',
       \})
 

autoload/fern/internal/drawer/hover_popup.vim

@@ -1,63 +1,99 @@
+let s:win = v:null
+let s:show_timer = 0
+
 function! fern#internal#drawer#hover_popup#init() abort
   if g:fern#disable_drawer_hover_popup
     return
   endif
 
-  if !exists('*popup_create')
-    call fern#logger#warn('hover popup is not supported, popup_create()
+  if !s:available()
+    call fern#logger#warn('hover popup is not supported, popup_create() or nvim environment
           \ does not exist. Disable this message
           \ with g:fern#disable_drawer_hover_popup.')
     return
   endif
 
   augroup fern_internal_drawer_hover_popup_init
     autocmd! * <buffer>
-    autocmd CursorMoved <buffer> call s:cursor_moved_event()
+    autocmd CursorMoved <buffer> call s:debounced_show()
+    autocmd BufLeave <buffer> call s:hide()
   augroup END
 endfunction
 
-function! fern#internal#drawer#hover_popup#calculate_node_char_offset(node) abort
-  " find line offset where label text begins
-  let line = getline('.')
-  let labelbegin = charidx(line, strridx(line, a:node.label))
-  let labelbegin = labelbegin < 0 ? 0 : labelbegin
-
-  let windowid = win_getid()
-
-  " get cursor position in drawer window (char- and byte-indexed)
-  let charpos = getcursorcharpos(windowid)
-  let pos = getcurpos(windowid)
-
-  " get cursor position relative to screen
-  let cursorpos = screenpos(windowid, pos[1], pos[2])
-
-  " calculate screen column where label text begins
-  return cursorpos['col'] - charpos[2] + labelbegin
+function! s:available() abort
+  let has_win = has('nvim') || exists('*popup_create')
+  return has_win && exists('*win_execute')
 endfunction
 
-function! fern#internal#drawer#hover_popup#should_display_popup() abort
-  return len(getline('.')) >= winwidth(0)
+function! s:debounced_show() abort
+  call s:hide()
+  let s:show_timer = timer_start(g:fern#drawer_hover_popup_delay, { -> s:show()  })
 endfunction
 
-function! s:cursor_moved_event() abort
-  let helper = fern#helper#new()
+function! s:show() abort
+  if &filetype !=# 'fern'
+    return
+  endif
+  call s:hide()
 
-  if fern#internal#drawer#hover_popup#should_display_popup()
-    call s:show_popup(helper)
+  if strdisplaywidth(getline('.')) <= winwidth(0)
+    return
   endif
-endfunction
 
-function! s:show_popup(helper) abort
-  let node = a:helper.sync.get_cursor_node()
+  let helper = fern#helper#new()
+  let node = helper.sync.get_cursor_node()
   if node is# v:null
     return
   endif
 
-  let label_offset = fern#internal#drawer#hover_popup#calculate_node_char_offset(node)
-  call popup_create(l:node.label, {
-        \ 'line': 'cursor',
-        \ 'col': label_offset + 1,
-        \ 'moved': 'any',
-        \})
+  let line = getline('.')
+  let width = strdisplaywidth(substitute(line, '[^[:print:]]*$', '', 'g'))
+  if has('nvim')
+    let s:win = nvim_open_win(nvim_create_buf(v:false, v:true), v:false, {
+    \    'relative': 'win',
+    \    'bufpos': [line('.') - 2, 0],
+    \    'width': width,
+    \    'height': 1,
+    \    'noautocmd': v:true,
+    \    'style': 'minimal',
+    \  })
+  else
+    let ui_width = screenpos(0, line('.'), 1).col - win_screenpos(0)[1]
+    let s:win = popup_create(line, {
+    \    'line': 'cursor',
+    \    'col': ui_width + 1,
+    \    'maxwidth': width,
+    \  })
+  endif
+
+  function! s:apply() abort closure
+    call setbufline('%', 1, line)
+    call helper.fern.renderer.syntax()
+    call helper.fern.renderer.highlight()
+    syntax clear FernRoot
+    syntax clear FernRootText
+
+    setlocal nowrap cursorline noswapfile nobuflisted buftype=nofile bufhidden=hide
+    if has('nvim')
+      setlocal winhighlight=NormalFloat:Normal
+    endif
+  endfunction
+  call win_execute(s:win, 'call s:apply()', v:true)
+endfunction
+
+function! s:hide() abort
+  call timer_stop(s:show_timer)
+
+  if s:win is# v:null
+    return
+  endif
+  if has('nvim')
+    if nvim_win_is_valid(s:win)
+      call nvim_win_close(s:win, v:true)
+    endif
+  else
+    call popup_close(s:win)
+  endif
+  let s:win = v:null
 endfunction
 

doc/fern.txt

@@ -417,7 +417,8 @@ VARIABLE						*fern-variable*
 	Set 1 to disable popups shown when the name of a node extends beyond
 	the width of the drawer.
 
-	Note that this feature is not supported in Neovim.
+	Note that this feature is required the |win_execute| and
+	popup/floatwin features. 
 
 	Default: 0
 
@@ -530,6 +531,11 @@ VARIABLE						*fern-variable*
 	open or close.
 	Default: |v:false|
 
+*g:fern#drawer_hover_popup_delay*
+	A |Number| value to specify the delay time to show the hover popup.
+	See |g:fern#disable_drawer_hover_popup|
+	Default: |0|
+
 *g:fern#mark_symbol*
 	A |String| which is used as a mark symbol text.
 	Note that users must restart Vim to apply changes.