refactor(win): native fzf flex layout

Use alternative preview layout instead of using a "transform",
simpler, and we don't need to take into account the hidden state of
the preview as well as decrease the minimum fzf version for native
fzf flex layout to 0.31 (instead of 0.46).

Has known issue upstream where if the layout changes upon resize
the hidden state of the preview is lost:
junegunn/fzf#4100

Closes #1527

OPTIONS.md

@@ -306,12 +306,13 @@ Preview border for native fzf previewers (i.e. `bat`, `git_status`), set to `nob
 
 Type: `string`, Default: `flex`
 
-Preview layout, possible values are `horizontal|vertical|flex`, when set to `flex` neovim width is
-tested against `winopts.preview.flip_columns`, when <= `vertical` is used, otherwise `horizontal`.
+Preview layout, possible values are `horizontal|vertical|flex`, when set to `flex` fzf window
+width is tested against `winopts.preview.flip_columns`, when <= `vertical` is used, otherwise
+`horizontal`.
 
 #### globals.winopts.preview.flip_columns
 
-Type: `number`, Default: `120`
+Type: `number`, Default: `100`
 
 Auto-detect the preview layout based on available width, see above note in `winopts.preview.layout`.
 

README.md

@@ -585,7 +585,7 @@ require'fzf-lua'.setup {
       vertical       = 'down:45%',      -- up|down:size
       horizontal     = 'right:60%',     -- right|left:size
       layout         = 'flex',          -- horizontal|vertical|flex
-      flip_columns   = 120,             -- #cols to switch to horizontal on flex
+      flip_columns   = 100,             -- #cols to switch to horizontal on flex
       -- Only used with the builtin previewer:
       title          = true,            -- preview border title (file/buf)?
       title_pos      = "center",        -- left|center|right, title alignment

doc/fzf-lua-opts.txt

@@ -1,4 +1,4 @@
-*fzf-lua-opts.txt*      For Neovim >= 0.8.0     Last change: 2024 September 26
+*fzf-lua-opts.txt*      For Neovim >= 0.8.0     Last change: 2024 September 27
 
 ==============================================================================
 Table of Contents                             *fzf-lua-opts-table-of-contents*
@@ -405,14 +405,14 @@ globals.winopts.preview.layout   *fzf-lua-opts-globals.winopts.preview.layout*
 Type: `string`, Default: `flex`
 
 Preview layout, possible values are `horizontal|vertical|flex`, when set to
-`flex` neovim width is tested against `winopts.preview.flip_columns`, when <=
-`vertical` is used, otherwise `horizontal`.
+`flex` fzf window width is tested against `winopts.preview.flip_columns`, when
+<= `vertical` is used, otherwise `horizontal`.
 
 
 
 globals.winopts.preview.flip_columns*fzf-lua-opts-globals.winopts.preview.flip_columns*
 
-Type: `number`, Default: `120`
+Type: `number`, Default: `100`
 
 Auto-detect the preview layout based on available width, see above note in
 `winopts.preview.layout`.

lua/fzf-lua/core.lua

@@ -376,28 +376,6 @@ M.fzf = function(contents, opts)
     if opts.__FZF_VERSION and opts.__FZF_VERSION >= 0.40 and previewer.zero then
       utils.map_set(opts, "keymap.fzf.zero", previewer:zero())
     end
-    if opts.__FZF_VERSION
-        and opts.__FZF_VERSION >= 0.46
-        and opts.winopts.preview.layout == "flex"
-        and tonumber(opts.winopts.preview.flip_columns) > 0
-        -- Only enable flex layout native rotate if zero event wasn't
-        -- set as it's most likely set by the default builtin previewer
-        and (not previewer.zero
-          -- or when using split mode for the background "empty previewer"
-          -- do not use when starting with a hidden previewer as this will
-          -- display the empty previewer when resizing (#1130)
-          or opts.winopts.split and opts.winopts.preview.hidden ~= "hidden")
-    then
-      local transformer = string.format(utils.__IS_WINDOWS
-        and "IF %%FZF_COLUMNS%% LEQ %d (echo change-preview-window:%s) "
-        .. "ELSE (echo change-preview-window:%s)"
-        or "[ $FZF_COLUMNS -le %d ] && echo change-preview-window:%s "
-        .. "|| echo change-preview-window:%s",
-        tonumber(opts.winopts.preview.flip_columns),
-        opts.winopts.preview.vertical,
-        opts.winopts.preview.horizontal)
-      utils.map_set(opts, "keymap.fzf.resize", string.format("transform(%s)", transformer))
-    end
     if type(previewer.preview_window) == "function" then
       -- do we need to override the preview_window args?
       -- this can happen with the builtin previewer
@@ -436,7 +414,7 @@ M.fzf = function(contents, opts)
   -- convert "exec_silent" actions to fzf's `execute-silent` binds
   opts = M.convert_reload_actions(opts.__reload_cmd or contents, opts)
   opts = M.convert_exec_silent_actions(opts)
-  local selected, exit_code = fzf.raw_fzf(contents, M.build_fzf_cli(opts),
+  local selected, exit_code = fzf.raw_fzf(contents, M.build_fzf_cli(opts, fzf_win),
     {
       fzf_bin = opts.fzf_bin,
       cwd = opts.cwd,
@@ -488,11 +466,33 @@ end
 
 ---@param o table
 ---@return string
-M.preview_window = function(o)
-  local hsplit = win:preview_splits_horizontally(o.winopts, 0)
-  local split = hsplit and o.winopts.preview.horizontal or o.winopts.preview.vertical
-  return ("%s:%s:%s:%s"):format(
-    o.winopts.preview.hidden, o.winopts.preview.border, o.winopts.preview.wrap, split)
+M.preview_window = function(o, fzf_win)
+  local layout
+  if o.__FZF_VERSION
+      and o.__FZF_VERSION >= 0.31
+      and o.winopts.preview.layout == "flex"
+      and tonumber(o.winopts.preview.flip_columns) > 0
+  then
+    -- Fzf's alternate layout calculates the available preview width in a horizontal split
+    -- (left/right), for the "<%d" condition to trigger the width should be test against a
+    -- calculated preview width after a horizontal split (and not vs total fzf window width)
+    -- to do that we must substract the calculated fzf "main" window width from `flip_columns`.
+    -- NOTE: sending `true` as first arg gets the no fullscreen width, otherwise we'll get
+    -- incosstent behavior when starting fullscreen
+    local columns = fzf_win:columns(true)
+    local fzf_prev_percent = tonumber(o.winopts.preview.horizontal:match(":(%d+)%%")) or 50
+    local fzf_main_width = math.ceil(columns * (100 - fzf_prev_percent) / 100)
+    local horizontal_min_width = o.winopts.preview.flip_columns - fzf_main_width + 1
+    if horizontal_min_width > 0 then
+      layout = string.format("%s,<%d(%s)",
+        o.winopts.preview.horizontal, horizontal_min_width, o.winopts.preview.vertical)
+    end
+  end
+  if not layout then
+    layout = fzf_win:fzf_preview_layout_str()
+  end
+  return string.format("%s:%s:%s:%s",
+    o.winopts.preview.hidden, o.winopts.preview.border, o.winopts.preview.wrap, layout)
 end
 
 -- Create fzf --color arguments from a table of vim highlight groups.
@@ -621,7 +621,7 @@ end
 
 ---@param opts table
 ---@return string[]
-M.build_fzf_cli = function(opts)
+M.build_fzf_cli = function(opts, fzf_win)
   opts.fzf_opts = vim.tbl_extend("force", config.globals.fzf_opts, opts.fzf_opts or {})
   -- copy/merge from globals
   for _, o in ipairs({ "fzf_colors", "keymap" }) do
@@ -681,7 +681,7 @@ M.build_fzf_cli = function(opts)
     end
   end
   if opts.fzf_opts["--preview-window"] == nil then
-    opts.fzf_opts["--preview-window"] = M.preview_window(opts)
+    opts.fzf_opts["--preview-window"] = M.preview_window(opts, fzf_win)
   end
   if opts.fzf_opts["--preview-window"] and opts.preview_offset and #opts.preview_offset > 0 then
     opts.fzf_opts["--preview-window"] =

lua/fzf-lua/defaults.lua

@@ -57,7 +57,7 @@ M.defaults                      = {
       vertical     = "down:45%",
       horizontal   = "right:60%",
       layout       = "flex",
-      flip_columns = 120,
+      flip_columns = 100,
       title        = true,
       title_pos    = "center",
       scrollbar    = "border",