Merge pull request #398 from brandon1024/hover-popup

Show popup when node name extends beyond drawer width

autoload/fern.vim

@@ -35,6 +35,7 @@ call s:Config.config(expand('<sfile>:p'), {
       \ 'disable_drawer_auto_winfixwidth': 0,
       \ 'disable_drawer_auto_resize': 0,
       \ 'disable_drawer_smart_quit': get(g:, 'disable_drawer_auto_quit', 0),
+      \ 'disable_drawer_hover_popup': 0,
       \ 'disable_drawer_auto_restore_focus': 0,
       \ 'default_hidden': 0,
       \ 'default_include': '',

autoload/fern/internal/drawer.vim

@@ -51,6 +51,7 @@ function! fern#internal#drawer#init() abort
   call fern#internal#drawer#auto_winfixwidth#init()
   call fern#internal#drawer#auto_restore_focus#init()
   call fern#internal#drawer#smart_quit#init()
+  call fern#internal#drawer#hover_popup#init()
   call fern#internal#drawer#resize()
   setlocal winfixwidth
 endfunction

autoload/fern/internal/drawer/hover_popup.vim

@@ -0,0 +1,63 @@
+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()
+          \ 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()
+  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
+endfunction
+
+function! fern#internal#drawer#hover_popup#should_display_popup() abort
+  return len(getline('.')) >= winwidth(0)
+endfunction
+
+function! s:cursor_moved_event() abort
+  let helper = fern#helper#new()
+
+  if fern#internal#drawer#hover_popup#should_display_popup()
+    call s:show_popup(helper)
+  endif
+endfunction
+
+function! s:show_popup(helper) abort
+  let node = a: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',
+        \})
+endfunction
+

doc/fern.txt

@@ -411,7 +411,15 @@ VARIABLE						*fern-variable*
 	of Neovim to avoid unwilling resize reported as #294
 	https://github.com/lambdalisue/fern.vim/issues/294
 
-	Default: 0 
+	Default: 0
+
+*g:fern#disable_drawer_hover_popup*
+	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.
+
+	Default: 0
 
 *g:fern#disable_drawer_smart_quit*
 	Set 1 to disable smart quit behavior when there are only two buffer