feat(menu): allow showing virtual text below entries (#92)

* feat(menu): allow showing virtual text below entries

* docs: document virt text property

* refactor(extmarks): use PascalCase for namespace id

README.md

@@ -1973,6 +1973,7 @@ multiple `dropbar_menu_entry_t` instances while a
 | `separator`  | [`dropbar_symbol_t`](#dropbar_symbol_t)   | separator to use in the entry                                               |
 | `padding`    | `{left: integer, right: integer}`         | padding to use between the menu entry and the menu border                   |
 | `components` | [`dropbar_symbol_t[]`](#dropbar_symbol_t) | components<sub>[`dropbar_symbol_t[]`](#dropbar_symbol_t)</sub> in the entry |
+| `virt_text`  | `string[][]?`                             | list of virtual text chunks to display below the entry                      |
 | `menu`       | [`dropbar_menu_t?`](#dropbar_menu_t)      | the menu the entry belongs to                                               |
 | `idx`        | `integer?`                                | the index of the entry in the menu                                          |
 

doc/dropbar.txt

@@ -1832,36 +1832,44 @@ contain multiple `dropbar_symbol_t` instances.
 
 `dropbar_menu_entry_t` has the following fields:
 
-dropbar_menu_t.separator                            *dropbar_menu_t.separator*
+dropbar_menu_entry_t.separator                      *dropbar_menu_t.separator*
 
  	Separator to use in the entry
 
 	Type ~
 	    `dropbar_symbol_t`
 
-dropbar_menu_t.padding                                *dropbar_menu_t.padding*
+dropbar_menu_entry_t.padding                          *dropbar_menu_t.padding*
 
  	Padding to use between the menu entry and the menu border
 
 	Type ~
 	    { left: integer, right: integer }
 
-dropbar_menu_t.components                          *dropbar_menu_t.components*
+dropbar_menu_entry_t.components                    *dropbar_menu_t.components*
 
 	Symbols got from sources |dropbar-developers-classes-dropbar_source_t|
 	in the entry
 
 	Type ~
 	    `dropbar_symbol_t`[]
 
-dropbar_menu_t.menu                                      *dropbar_menu_t.menu*
+dropbar_menu_entry_t.virt_text                      *dropbar_menu_t.virt_text*
+
+	Symbols got from sources |dropbar-developers-classes-dropbar_source_t|
+	in the entry
+
+	Type ~
+	    `string`[][]?
+
+dropbar_menu_entry_t.menu                                *dropbar_menu_t.menu*
 
  	The menu the entry belongs to
 
 	Type ~
 	    `dropbar_menu_t`?
 
-dropbar_menu_t.idx                                        *dropbar_menu_t.idx*
+dropbar_menu_entry_t.idx                                  *dropbar_menu_t.idx*
 
  	The index of the entry in the menu
 

lua/dropbar/menu.lua

@@ -17,6 +17,7 @@ _G.dropbar.menus = {}
 ---@field separator dropbar_symbol_t
 ---@field padding {left: integer, right: integer}
 ---@field components dropbar_symbol_t[]
+---@field virt_text string[][]?
 ---@field menu dropbar_menu_t? the menu the entry belongs to
 ---@field idx integer? the index of the entry in the menu
 local dropbar_menu_entry_t = {}
@@ -26,6 +27,7 @@ dropbar_menu_entry_t.__index = dropbar_menu_entry_t
 ---@field separator dropbar_symbol_t?
 ---@field padding {left: integer, right: integer}?
 ---@field components dropbar_symbol_t[]?
+---@field virt_text string[][]?
 ---@field menu dropbar_menu_t? the menu the entry belongs to
 ---@field idx integer? the index of the entry in the menu
 
@@ -398,8 +400,9 @@ end
 ---highlights to the buffer
 function dropbar_menu_t:fill_buf()
   local lines = {} ---@type string[]
+  local extmarks = {} ---@type table<integer, string[][]>
   local hl_info = {} ---@type dropbar_menu_hl_info_t[][]
-  for _, entry in ipairs(self.entries) do
+  for i, entry in ipairs(self.entries) do
     local line, entry_hl_info = entry:cat()
     -- Pad lines with spaces to the width of the window
     -- This is to make sure hl-DropBarMenuCurrentContext colors
@@ -413,9 +416,29 @@ function dropbar_menu_t:fill_buf()
         )
     )
     table.insert(hl_info, entry_hl_info)
+    if entry.virt_text then
+      table.insert(extmarks, i, entry.virt_text)
+    end
   end
   vim.api.nvim_buf_set_lines(self.buf, 0, -1, false, lines)
   self:add_hl(hl_info)
+
+  local extmark_ns = vim.api.nvim_create_namespace('DropBarExtmarks')
+  vim.api.nvim_buf_clear_namespace(self.buf, extmark_ns, 0, -1)
+
+  for i, virt_text in pairs(extmarks) do
+    if type(i) == 'number' then
+      vim.api.nvim_buf_set_extmark(
+        self.buf,
+        extmark_ns,
+        i - 1, -- 0-indexed
+        0,
+        {
+          virt_lines = { virt_text },
+        }
+      )
+    end
+  end
 end
 
 ---Make a buffer for the menu and set buffer-local keymaps