feat(event): add TreeRendered (#2324)

* add TreeRendered event

* pass bufnr and winnr to TreeRendered event

---------

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

doc/nvim-tree-lua.txt

@@ -2235,6 +2235,15 @@ e.g. handler for node renamed: >
                 handler parameters: ~
                   {buf}          `{number} `API buffer handle (buffer number)
 
+- Event.TreeRendered
+                Invoked every time the tree is redrawn. Normally this event
+                happens after |Event.TreeOpen| except that handlers of this
+                one will have access to the tree buffer populated with the
+                final content.
+                handler parameters: ~
+                  {bufnr}          `{number} `API buffer handle (buffer number)
+                  {winnr}          `{number} `API window handle (window number)
+
 |nvim_tree_events_startup|
 
 There are two special startup events in the form of User autocommands:

lua/nvim-tree/events.lua

@@ -18,6 +18,7 @@ M.Event = {
   FolderRemoved = "FolderRemoved",
   Resize = "Resize",
   TreeAttachedPost = "TreeAttachedPost",
+  TreeRendered = "TreeRendered",
 }
 
 local function get_handlers(event_name)
@@ -104,4 +105,9 @@ function M._dispatch_tree_attached_post(buf)
   dispatch(M.Event.TreeAttachedPost, buf)
 end
 
+--@private
+function M._dispatch_on_tree_rendered(bufnr, winnr)
+  dispatch(M.Event.TreeRendered, { bufnr = bufnr, winnr = winnr })
+end
+
 return M

lua/nvim-tree/renderer/init.lua

@@ -2,6 +2,7 @@ local core = require "nvim-tree.core"
 local diagnostics = require "nvim-tree.diagnostics"
 local log = require "nvim-tree.log"
 local view = require "nvim-tree.view"
+local events = require "nvim-tree.events"
 local modified = require "nvim-tree.renderer.components.modified"
 
 local _padding = require "nvim-tree.renderer.components.padding"
@@ -89,6 +90,8 @@ function M.draw(unloaded_bufnr)
   view.grow_from_content()
 
   log.profile_end(profile)
+
+  events._dispatch_on_tree_rendered(bufnr, view.get_winnr())
 end
 
 function M.setup(opts)