feat(renderer): add renderer.indent_width (#1505)

* feat: add config option for a tree indent width

add 'indent_width' option to configure visible indent for tree nesting
levels (default is 2).

* add 'bottom' char for a corner extension

* apply stylua formatting

* provide value constraints in documentation

* limit minimal indent width

* make marker symbols have one utf8 char width

* match stylua formatting

* add the commentary regarding utf-8 first symbol match

lua/nvim-tree/renderer/builder.lua

@@ -258,9 +258,9 @@ function Builder:_build_line(node, idx, num_children)
   self.index = self.index + 1
 
   if node.open then
-    self.depth = self.depth + 2
+    self.depth = self.depth + 1
     self:build(node)
-    self.depth = self.depth - 2
+    self.depth = self.depth - 1
   end
 end
 

lua/nvim-tree/renderer/components/padding.lua

@@ -25,30 +25,33 @@ local function get_padding_indent_markers(depth, idx, nodes_number, markers, wit
 
   if depth > 0 then
     local has_folder_sibling = check_siblings_for_folder(node, with_arrows)
-    local rdepth = depth / 2
-    markers[rdepth] = idx ~= nodes_number
-    for i = 1, rdepth do
+    local indent = string.rep(" ", M.config.indent_width - 1)
+    markers[depth] = idx ~= nodes_number
+    for i = 1, depth do
       local glyph
-      if idx == nodes_number and i == rdepth then
+      if idx == nodes_number and i == depth then
+        local bottom_width = M.config.indent_width
+          - 2
+          + (with_arrows and not inline_arrows and has_folder_sibling and 2 or 0)
         glyph = M.config.indent_markers.icons.corner
-      elseif markers[i] and i == rdepth then
-        glyph = M.config.indent_markers.icons.item
+          .. string.rep(M.config.indent_markers.icons.bottom, bottom_width)
+          .. (M.config.indent_width > 1 and " " or "")
+      elseif markers[i] and i == depth then
+        glyph = M.config.indent_markers.icons.item .. indent
       elseif markers[i] then
-        glyph = M.config.indent_markers.icons.edge
+        glyph = M.config.indent_markers.icons.edge .. indent
       else
-        glyph = M.config.indent_markers.icons.none
+        glyph = M.config.indent_markers.icons.none .. indent
       end
 
-      if not with_arrows or (inline_arrows and (rdepth ~= i or not node.nodes)) then
-        padding = padding .. glyph .. " "
+      if not with_arrows or (inline_arrows and (depth ~= i or not node.nodes)) then
+        padding = padding .. glyph
       elseif inline_arrows then
         padding = padding
-      elseif idx == nodes_number and i == rdepth and has_folder_sibling then
-        padding = padding .. base_padding .. glyph .. "── "
-      elseif rdepth == i and not node.nodes and has_folder_sibling then
-        padding = padding .. base_padding .. glyph .. " " .. base_padding
+      elseif idx ~= nodes_number and depth == i and not node.nodes and has_folder_sibling then
+        padding = padding .. base_padding .. glyph .. base_padding
       else
-        padding = padding .. base_padding .. glyph .. " "
+        padding = padding .. base_padding .. glyph
       end
     end
   end
@@ -71,11 +74,12 @@ function M.get_padding(depth, idx, nodes_number, node, markers)
   local show_arrows = M.config.icons.show.folder_arrow
   local show_markers = M.config.indent_markers.enable
   local inline_arrows = M.config.indent_markers.inline_arrows
+  local indent_width = M.config.indent_width
 
   if show_markers then
     padding = padding .. get_padding_indent_markers(depth, idx, nodes_number, markers, show_arrows, inline_arrows, node)
   else
-    padding = padding .. string.rep(" ", depth)
+    padding = padding .. string.rep(" ", depth * indent_width)
   end
 
   if show_arrows then
@@ -87,6 +91,22 @@ end
 
 function M.setup(opts)
   M.config = opts.renderer
+
+  if M.config.indent_width < 1 then
+    M.config.indent_width = 1
+  end
+
+  local function check_marker(symbol)
+    if #symbol == 0 then
+      return " "
+    end
+    -- return the first character from the UTF-8 encoded string; we may use utf8.codes from Lua 5.3 when available
+    return symbol:match "[%z\1-\127\194-\244][\128-\191]*"
+  end
+
+  for k, v in pairs(M.config.indent_markers.icons) do
+    M.config.indent_markers.icons[k] = check_marker(v)
+  end
 end
 
 return M