[vim] Support relative-to-window positioning of popup (#2443)

Co-authored-by: Junegunn Choi <junegunn.c@gmail.com>

3 files changed, 33 insertions, 9 deletions

diff --git a/README-VIM.md b/README-VIM.md
index b934c232..b54c4fae 100644
--- a/README-VIM.md
+++ b/README-VIM.md
@@ -127,9 +127,15 @@ let g:fzf_action = {
   \ 'ctrl-v': 'vsplit' }
 
 " Default fzf layout
-" - Popup window
+" - Popup window (center of the screen)
 let g:fzf_layout = { 'window': { 'width': 0.9, 'height': 0.6 } }
 
+" - Popup window (center of the current window)
+let g:fzf_layout = { 'window': { 'width': 0.9, 'height': 0.6, 'relative': v:true } }
+
+" - Popup window (anchored to the bottom of the current window)
+let g:fzf_layout = { 'window': { 'width': 0.9, 'height': 0.6, 'relative': v:true, 'yoffset': 1.0 } }
+
 " - down / up / left / right
 let g:fzf_layout = { 'down': '40%' }
 
@@ -302,6 +308,7 @@ following options are allowed:
 - Optional:
     - `yoffset` [float default 0.5 range [0 ~ 1]]
     - `xoffset` [float default 0.5 range [0 ~ 1]]
+    - `relative` [boolean default v:false]
     - `border` [string default `rounded`]: Border style
         - `rounded` / `sharp` / `horizontal` / `vertical` / `top` / `bottom` / `left` / `right` / `no[ne]`
 
@@ -410,6 +417,7 @@ The latest versions of Vim and Neovim include builtin terminal emulator
 " Optional:
 " - xoffset [float default 0.5 range [0 ~ 1]]
 " - yoffset [float default 0.5 range [0 ~ 1]]
+" - relative [boolean default v:false]
 " - border [string default 'rounded']: Border style
 "   - 'rounded' / 'sharp' / 'horizontal' / 'vertical' / 'top' / 'bottom' / 'left' / 'right'
 let g:fzf_layout = { 'window': { 'width': 0.9, 'height': 0.6 } }
diff --git a/doc/fzf.txt b/doc/fzf.txt
index 43ebb1c4..ed8a9e3a 100644
--- a/doc/fzf.txt
+++ b/doc/fzf.txt
@@ -1,4 +1,4 @@
-fzf.txt	fzf	Last change: January 3 2021
+fzf.txt	fzf	Last change: April 17 2021
 FZF - TABLE OF CONTENTS                                            *fzf* *fzf-toc*
 ==============================================================================
 
@@ -155,9 +155,15 @@ Examples~
       \ 'ctrl-v': 'vsplit' }
 
     " Default fzf layout
-    " - Popup window
+    " - Popup window (center of the screen)
     let g:fzf_layout = { 'window': { 'width': 0.9, 'height': 0.6 } }
 
+    " - Popup window (center of the current window)
+    let g:fzf_layout = { 'window': { 'width': 0.9, 'height': 0.6, 'relative': v:true } }
+
+    " - Popup window (anchored to the bottom of the current window)
+    let g:fzf_layout = { 'window': { 'width': 0.9, 'height': 0.6, 'relative': v:true, 'yoffset': 1.0 } }
+
     " - down / up / left / right
     let g:fzf_layout = { 'down': '40%' }
 
@@ -318,6 +324,7 @@ following options are allowed:
  - Optional:
    - `yoffset` [float default 0.5 range [0 ~ 1]]
    - `xoffset` [float default 0.5 range [0 ~ 1]]
+   - `relative` [boolean default v:false]
    - `border` [string default `rounded`]: Border style
      - `rounded` / `sharp` / `horizontal` / `vertical` / `top` / `bottom` / `left` / `right` / `no[ne]`
 
@@ -372,7 +379,7 @@ last `fullscreen` argument of `fzf#wrap` (see :help <bang>).
 Our `:LS` command will be much more useful if we can pass a directory argument
 to it, so that something like `:LS /tmp` is possible.
 >
-    command! -bang -complete=dir -nargs=* LS
+    command! -bang -complete=dir -nargs=? LS
         \ call fzf#run(fzf#wrap({'source': 'ls', 'dir': <q-args>}, <bang>0))
 <
 Lastly, if you have enabled `g:fzf_history_dir`, you might want to assign a
@@ -380,7 +387,7 @@ unique name to our command and pass it as the first argument to `fzf#wrap`.
 >
     " The query history for this command will be stored as 'ls' inside g:fzf_history_dir.
     " The name is ignored if g:fzf_history_dir is not defined.
-    command! -bang -complete=dir -nargs=* LS
+    command! -bang -complete=dir -nargs=? LS
         \ call fzf#run(fzf#wrap('ls', {'source': 'ls', 'dir': <q-args>}, <bang>0))
 <
 
@@ -423,6 +430,7 @@ Starting fzf in a popup window~
     " Optional:
     " - xoffset [float default 0.5 range [0 ~ 1]]
     " - yoffset [float default 0.5 range [0 ~ 1]]
+    " - relative [boolean default v:false]
     " - border [string default 'rounded']: Border style
     "   - 'rounded' / 'sharp' / 'horizontal' / 'vertical' / 'top' / 'bottom' / 'left' / 'right'
     let g:fzf_layout = { 'window': { 'width': 0.9, 'height': 0.6 } }
diff --git a/plugin/fzf.vim b/plugin/fzf.vim
index 26dcf974..9cebed48 100644
--- a/plugin/fzf.vim
+++ b/plugin/fzf.vim
@@ -972,11 +972,19 @@ else
 endif
 
 function! s:popup(opts) abort
+  let xoffset = get(a:opts, 'xoffset', 0.5)
+  let yoffset = get(a:opts, 'yoffset', 0.5)
+  let relative = get(a:opts, 'relative', 0)
+
+  " Use current window size for positioning relatively positioned popups
+  let columns = relative ? winwidth(0) : &columns
+  let lines = relative ? winheight(0) : &lines
+
   " Size and position
-  let width = min([max([8, a:opts.width > 1 ? a:opts.width : float2nr(&columns * a:opts.width)]), &columns])
-  let height = min([max([4, a:opts.height > 1 ? a:opts.height : float2nr(&lines * a:opts.height)]), &lines - has('nvim')])
-  let row = float2nr(get(a:opts, 'yoffset', 0.5) * (&lines - height))
-  let col = float2nr(get(a:opts, 'xoffset', 0.5) * (&columns - width))
+  let width = min([max([8, a:opts.width > 1 ? a:opts.width : float2nr(columns * a:opts.width)]), columns])
+  let height = min([max([4, a:opts.height > 1 ? a:opts.height : float2nr(lines * a:opts.height)]), lines - has('nvim')])
+  let row = float2nr(yoffset * (lines - height)) + (relative ? win_screenpos(0)[0] : 0)
+  let col = float2nr(xoffset * (columns - width)) + (relative ? win_screenpos(0)[1] : 0)
 
   " Managing the differences
   let row = min([max([0, row]), &lines - has('nvim') - height])