Improve 'zoom' related actions

- The 'zoom' action ask users for the desired ratio or use v:count
- The 'zoom:reset' action is used to get the original width back

Now user can use "7z" to get 70% width drawer and "Z" to get back.

This is mainly for helping a usage explained in a feature request #309
#309

Author: lambdalisue

autoload/fern/mapping/drawer.vim

@@ -1,11 +1,12 @@
 function! fern#mapping#drawer#init(disable_default_mappings) abort
-  nnoremap <buffer><silent> <Plug>(fern-action-zoom:half) :<C-u>call <SID>call('zoom', 0.4)<CR>
-  nnoremap <buffer><silent> <Plug>(fern-action-zoom:full) :<C-u>call <SID>call('zoom', 0.9)<CR>
-
-  nmap <buffer> <Plug>(fern-action-zoom) <Plug>(fern-action-zoom:half)
+  nnoremap <buffer><silent> <Plug>(fern-action-zoom) :<C-u>call <SID>call('zoom')<CR>
+  nnoremap <buffer><silent> <Plug>(fern-action-zoom:reset) :<C-u>call <SID>call('zoom_reset')<CR>
+  nmap <buffer><silent> <Plug>(fern-action-zoom:half) 4<Plug>(fern-action-zoom)
+  nmap <buffer><silent> <Plug>(fern-action-zoom:full) 9<Plug>(fern-action-zoom)
 
   if !a:disable_default_mappings
     nmap <buffer><nowait> z <Plug>(fern-action-zoom)
+    nmap <buffer><nowait> Z <Plug>(fern-action-zoom:reset)
   endif
 endfunction
 
@@ -16,9 +17,35 @@ function! s:call(name, ...) abort
         \)
 endfunction
 
-function! s:map_zoom(helper, alpha) abort
-  if fern#internal#drawer#is_drawer()
-    let width = &columns * a:alpha
-    execute printf('%d wincmd |', float2nr(width))
+function! s:map_zoom(helper) abort
+  if !fern#internal#drawer#is_drawer()
+    call fern#warn('zoom is available only on drawer')
+    return
+  endif
+  let alpha = v:count
+  if alpha <= 0 || alpha > 10
+    let alpha = s:input_alpha('Width ratio [1-10]: ')
   endif
+  let alpha = str2float(alpha)
+  let width = &columns * (alpha / 10)
+  execute 'vertical resize' float2nr(width)
+endfunction
+
+function! s:map_zoom_reset(helper) abort
+  if !fern#internal#drawer#is_drawer()
+    call fern#warn('zoom:resize is available only on drawer')
+    return
+  endif
+  call fern#internal#drawer#resize()
+endfunction
+
+function! s:input_alpha(prompt) abort
+  while v:true
+    let result = input(a:prompt)
+    if result =~# '^\%(10\|[1-9]\)$'
+      redraw | echo ''
+      return result
+    endif
+    redraw | echo 'Please input a digit from 1 to 10'
+  endwhile
 endfunction

doc/fern.txt

@@ -781,16 +781,22 @@ See |fern-action| for more detail.
 -----------------------------------------------------------------------------
 GLOBAL							*fern-mapping-global*
 
-*<Plug>(fern-action-zoom:half)*
-	Zoom width of the drawer style fern to half of the global width.
-	The original window width will be restored once user leave the window.
+*<Plug>(fern-action-zoom)*
+	Zoom width of the drawer style fern to the ratio of the global width.
+	It prompt users to ask a desired ratio of the width if no |v:count| is
+	given. Users can use 1 to 10 for the ratio.
 	It only works on a drawer style fern window.
 
-*<Plug>(fern-action-zoom:full)*
-	Zoom width of the drawer style fern to full of the global width.
-	The original window width will be restored once user leave the window.
+*<Plug>(fern-action-zoom:reset)*
+	Reset the width of the drawer style fern to its original width.
 	It only works on a drawer style fern window.
 
+*<Plug>(fern-action-zoom:half)*
+	This is an alias of "4<Plug>(fern-action-zoom)"
+
+*<Plug>(fern-action-zoom:full)*
+	This is an alias of "9<Plug>(fern-action-zoom)"
+
 *<Plug>(fern-action-hidden:set)*
 	Show hidden nodes. For example hidden nodes in file:// scheme is a
 	file or directory starts from '.' character.