feat(view): add view.width.padding (#1941)

* fix: variable width accounts for sign/number columns

* Add dynamic sizing padding options

with https://github.com/neovim/neovim/pull/20621 merged in it is now
possible to fully customize the status-column in nvim (the column on the
left containing line-numbers, fold info, signs and borders).

A fair few cool implementations have popped up like:
- https://github.com/CKolkey/config/blob/master/nvim/after/plugin/statuscolumn.lua
- https://github.com/luukvbaal/statuscol.nvim
- and my own personal one (based on CKolkey's fantastic work) https://git.hendrikpeter.net/hendrikpeter/pico-vim/-/blob/main/lua/peva/status_column.lua

The problem with nvim-tree however is that dynamic sizing doesn't take
the custom size of a status column into account and the end of file
names get clipped off. This little patch should fix that (and give some
examples to help other status_column modders get started).

Thanks for looking at this and thanks for making this amazing plugin,
I've been using it for a while and I really like it!

* allow padding function, update docs, rollback readme

* typo in example setup

* help formatting

---------

Co-authored-by: Alexander Courtis <alex@courtis.org>

README.md

@@ -74,7 +74,7 @@ require("nvim-tree").setup()
 require("nvim-tree").setup({
   sort_by = "case_sensitive",
   view = {
-    adaptive_size = true,
+    width = 30,
     mappings = {
       list = {
         { key = "u", action = "dir_up" },

doc/nvim-tree-lua.txt

@@ -81,6 +81,7 @@ Setup should be run in a lua file or in a |lua-heredoc| if using in a vim file.
     require("nvim-tree").setup({
       sort_by = "case_sensitive",
       view = {
+        width = 30,
         mappings = {
           list = {
             { key = "u", action = "dir_up" },
@@ -740,6 +741,10 @@ Window / buffer setup.
         Maximum dynamic width, -1 for unbounded.
           Type: `string | number | function`, Default: `-1`
 
+        *nvim-tree.view.width.padding*
+        Extra padding to the right.
+          Type: `string | number | function`, Default: `1`
+
     *nvim-tree.view.side*
     Side of the tree, can be `"left"`, `"right"`.
       Type: `string`, Default: `"left"`

lua/nvim-tree/view.lua

@@ -6,6 +6,7 @@ local log = require "nvim-tree.log"
 
 local DEFAULT_MIN_WIDTH = 30
 local DEFAULT_MAX_WIDTH = -1
+local DEFAULT_PADDING = 1
 
 M.View = {
   adaptive_size = false,
@@ -102,7 +103,6 @@ local function create_buffer(bufnr)
 end
 
 local function get_size(size)
-  size = size or M.View.width
   if type(size) == "number" then
     return size
   elseif type(size) == "function" then
@@ -113,6 +113,11 @@ local function get_size(size)
   return math.floor(vim.o.columns * percent_as_decimal)
 end
 
+local function get_width(size)
+  size = size or M.View.width
+  return get_size(size)
+end
+
 local move_tbl = {
   left = "H",
   right = "L",
@@ -252,8 +257,16 @@ end
 local function grow()
   local starts_at = M.is_root_folder_visible(require("nvim-tree.core").get_cwd()) and 1 or 0
   local lines = vim.api.nvim_buf_get_lines(M.get_bufnr(), starts_at, -1, false)
-  -- 1 column of right-padding to indicate end of path
+  -- number of columns of right-padding to indicate end of path
-  local padding = 3
+  local padding = get_size(M.View.padding)
+
+  -- account for sign/number columns etc.
+  local wininfo = vim.fn.getwininfo(M.get_winnr())
+  if type(wininfo) == "table" and type(wininfo[1]) == "table" then
+    padding = padding + wininfo[1].textoff
+  end
+  print(padding)
+
   local resizing_width = M.View.initial_width - padding
   local max_width
 
@@ -261,7 +274,7 @@ local function grow()
   if M.View.max_width == -1 then
     max_width = -1
   else
-    max_width = get_size(M.View.max_width) - padding
+    max_width = get_width(M.View.max_width) - padding
   end
 
   for _, l in pairs(lines) do
@@ -313,7 +326,7 @@ function M.resize(size)
     return
   end
 
-  local new_size = get_size()
+  local new_size = get_width()
   vim.api.nvim_win_set_width(M.get_winnr(), new_size)
 
   events._dispatch_on_tree_resize(new_size)
@@ -520,12 +533,13 @@ function M.setup(opts)
     M.View.adaptive_size = true
     M.View.width = options.width.min or DEFAULT_MIN_WIDTH
     M.View.max_width = options.width.max or DEFAULT_MAX_WIDTH
+    M.View.padding = options.width.padding or DEFAULT_PADDING
   else
     M.View.adaptive_size = false
     M.View.width = options.width
   end
 
-  M.View.initial_width = get_size()
+  M.View.initial_width = get_width()
 end
 
 return M