feat: Massive performance improvement, only parse / render visible range

## Details

This is a pretty large overhaul to how events are handled by this plugin.

Instead of parsing & rendering the entire buffer only render the lines
within the neovim viewport + small buffer. This involves putting ranges
on the iter_captures calls as well as when parsing the language trees.
All this logic is centralized in the Context class.

Add a debounce on the updates that defaults to 100ms, users can modify
this if they prefer more frequent udpates, this would impact overall
neovim performance.

The performance is now to the point where doing the Obsidian like
behavior of rendering all lines in insert mode except the line being
modified works really well, I may make this the default experience
in a future update. This does involve adding all the *I events to
our autocommand, I have made this based on the render_modes value
to avoid listening to this events if it is not necessary.

We do parse the ranges more frequently since cursor movements could
put the marks out of range so it's not a complete win in all cases,
worst case being small files that can be contained in the viewport.
Still these are typically so fast anyway that doing it more times
is hard to notice.

Author: MeanderingProgrammer

Diff for: README.md

@@ -125,6 +125,9 @@ require('render-markdown').setup({
     -- Maximum file size (in MB) that this plugin will attempt to render
     -- Any file larger than this will effectively be ignored
     max_file_size = 1.5,
+    -- Milliseconds that must pass before updating marks, updates occur
+    -- within the context of the visible window, not the entire buffer
+    debounce = 100,
     -- Capture groups that get pulled from markdown
     markdown_query = [[
         (atx_heading [
@@ -427,8 +430,8 @@ require('render-markdown').setup({
     -- More granular configuration mechanism, allows different aspects of buffers
     -- to have their own behavior. Values default to the top level configuration
     -- if no override is provided. Supports the following fields:
-    --   enabled, max_file_size, render_modes, anti_conceal, heading, code, dash, bullet,
-    --   checkbox, quote, pipe_table, callout, link, sign, win_options
+    --   enabled, max_file_size, debounce, render_modes, anti_conceal, heading, code,
+    --   dash, bullet, checkbox, quote, pipe_table, callout, link, sign, win_options
     overrides = {
         -- Overrides for different buftypes, see :h 'buftype'
         buftype = {

Diff for: benches/medium_spec.lua

@@ -4,14 +4,14 @@ local util = require('benches.util')
 
 describe('medium.md', function()
     it('default', function()
-        local base_marks = 2998
-        util.between(25, 75, util.setup('temp/medium.md'))
+        local base_marks = 46
+        util.between(20, 30, util.setup('temp/medium.md'))
         util.num_marks(base_marks)
 
-        util.between(0, 1, util.move_down(3))
+        util.between(0, 5, util.move_down(3))
         util.num_marks(base_marks + 2)
 
-        util.between(25, 50, util.insert_mode())
+        util.between(1, 15, util.insert_mode())
         util.num_marks(base_marks + 2)
     end)
 end)

Diff for: benches/medium_table_spec.lua

@@ -4,14 +4,14 @@ local util = require('benches.util')
 
 describe('medium-table.md', function()
     it('default', function()
-        local base_marks = 30698
-        util.between(450, 600, util.setup('temp/medium-table.md'))
+        local base_marks = 468
+        util.between(80, 105, util.setup('temp/medium-table.md'))
         util.num_marks(base_marks)
 
-        util.between(1, 5, util.move_down(1))
+        util.between(1, 20, util.move_down(1))
         util.num_marks(base_marks + 2)
 
-        util.between(400, 550, util.insert_mode())
+        util.between(5, 30, util.insert_mode())
         util.num_marks(base_marks + 2)
     end)
 end)

Diff for: benches/readme_spec.lua

@@ -4,14 +4,14 @@ local util = require('benches.util')
 
 describe('README.md', function()
     it('default', function()
-        local base_marks = 441
-        util.between(25, 75, util.setup('README.md'))
+        local base_marks = 55
+        util.between(30, 50, util.setup('README.md'))
         util.num_marks(base_marks)
 
-        util.between(0, 1, util.move_down(1))
+        util.between(1, 5, util.move_down(1))
         util.num_marks(base_marks + 2)
 
-        util.between(20, 40, util.insert_mode())
+        util.between(10, 20, util.insert_mode())
         util.num_marks(base_marks + 2)
     end)
 end)

Diff for: benches/util.lua

@@ -8,13 +8,11 @@ local truthy = assert.truthy
 local M = {}
 
 ---@param file string
----@param opts? render.md.UserConfig
 ---@return number
-function M.setup(file, opts)
+function M.setup(file)
     return M.time(function()
-        require('render-markdown').setup(opts)
+        require('render-markdown').setup({ debounce = 0 })
         vim.cmd('e ' .. file)
-        vim.wait(0)
     end)
 end
 
@@ -25,15 +23,13 @@ function M.move_down(n)
         M.feed(string.format('%dj', n))
         -- Unsure why, but the CursorMoved event needs to be triggered manually
         vim.api.nvim_exec_autocmds('CursorMoved', {})
-        vim.wait(0)
     end)
 end
 
 ---@return number
 function M.insert_mode()
     return M.time(function()
         M.feed('i')
-        vim.wait(0)
     end)
 end
 
@@ -43,6 +39,7 @@ end
 function M.time(f)
     local start = vim.uv.hrtime()
     f()
+    vim.wait(0)
     return (vim.uv.hrtime() - start) / 1e+6
 end
 

Diff for: doc/render-markdown.txt

@@ -158,6 +158,9 @@ Full Default Configuration ~
         -- Maximum file size (in MB) that this plugin will attempt to render
         -- Any file larger than this will effectively be ignored
         max_file_size = 1.5,
+        -- Milliseconds that must pass before updating marks, updates occur
+        -- within the context of the visible window, not the entire buffer
+        debounce = 100,
         -- Capture groups that get pulled from markdown
         markdown_query = [[
             (atx_heading [
@@ -460,8 +463,8 @@ Full Default Configuration ~
         -- More granular configuration mechanism, allows different aspects of buffers
         -- to have their own behavior. Values default to the top level configuration
         -- if no override is provided. Supports the following fields:
-        --   enabled, max_file_size, render_modes, anti_conceal, heading, code, dash, bullet,
-        --   checkbox, quote, pipe_table, callout, link, sign, win_options
+        --   enabled, max_file_size, debounce, render_modes, anti_conceal, heading, code,
+        --   dash, bullet, checkbox, quote, pipe_table, callout, link, sign, win_options
         overrides = {
             -- Overrides for different buftypes, see :h 'buftype'
             buftype = {

Diff for: lua/render-markdown/buffer_state.lua

@@ -0,0 +1,32 @@
+---@class render.md.BufferState
+---@field private buf integer
+---@field private timer uv_timer_t
+---@field private running boolean
+---@field state? 'default'|'rendered'
+local BufferState = {}
+BufferState.__index = BufferState
+
+---@param buf integer
+---@return render.md.BufferState
+function BufferState.new(buf)
+    local self = setmetatable({}, BufferState)
+    self.buf = buf
+    self.timer = (vim.uv or vim.loop).new_timer()
+    self.running = false
+    self.state = nil
+    return self
+end
+
+---@param ms integer
+---@param cb fun(buf: integer)
+function BufferState:debounce(ms, cb)
+    self.timer:start(ms, 0, function()
+        self.running = false
+    end)
+    if not self.running then
+        self.running = true
+        vim.schedule_wrap(cb)(self.buf)
+    end
+end
+
+return BufferState

Diff for: lua/render-markdown/context.lua

@@ -1,6 +1,8 @@
 ---@class render.md.Context
 ---@field private buf integer
 ---@field private win integer
+---@field private top integer
+---@field private bottom integer
 ---@field private conceallevel integer
 ---@field private conceal? table<integer, [integer, integer][]>
 ---@field private links table<integer, [integer, integer, string][]>
@@ -9,10 +11,15 @@ Context.__index = Context
 
 ---@param buf integer
 ---@param win integer
-function Context.new(buf, win)
+---@param offset integer
+function Context.new(buf, win, offset)
     local self = setmetatable({}, Context)
     self.buf = buf
     self.win = win
+    local top = vim.api.nvim_win_call(win, vim.fn.winsaveview).topline - 1
+    local height = vim.api.nvim_win_get_height(win)
+    self.top = math.max(top - offset, 0)
+    self.bottom = top + height + offset
     self.conceallevel = vim.api.nvim_get_option_value('conceallevel', { scope = 'local', win = win })
     self.conceal = nil
     self.links = {}
@@ -40,6 +47,28 @@ function Context:get_width()
     return vim.api.nvim_win_get_width(self.win)
 end
 
+---@return Range2
+function Context:range()
+    return { self.top, self.bottom }
+end
+
+---@param node TSNode
+---@return boolean
+function Context:contains_node(node)
+    local top, _, bottom, _ = node:range()
+    return top <= self.bottom and bottom >= self.top
+end
+
+---@param root TSNode
+---@param query vim.treesitter.Query
+---@param cb fun(capture: string, node: TSNode, metadata: vim.treesitter.query.TSMetadata)
+function Context:query(root, query, cb)
+    for id, node, metadata in query:iter_captures(root, self.buf, self.top, self.bottom) do
+        local capture = query.captures[id]
+        cb(capture, node, metadata)
+    end
+end
+
 ---@param row integer
 ---@return [integer, integer][]
 function Context:get_conceal(row)
@@ -58,6 +87,7 @@ function Context:compute_conceal()
     end
     local ranges = {}
     local parser = vim.treesitter.get_parser(self.buf)
+    parser:parse(self:range())
     parser:for_each_tree(function(tree, language_tree)
         local nodes = self:compute_conceal_nodes(language_tree:lang(), tree:root())
         for _, node in ipairs(nodes) do
@@ -76,6 +106,9 @@ end
 ---@param root TSNode
 ---@return TSNode[]
 function Context:compute_conceal_nodes(language, root)
+    if not self:contains_node(root) then
+        return {}
+    end
     if not vim.tbl_contains({ 'markdown', 'markdown_inline' }, language) then
         return {}
     end
@@ -84,11 +117,11 @@ function Context:compute_conceal_nodes(language, root)
         return {}
     end
     local nodes = {}
-    for _, node, metadata in query:iter_captures(root, self.buf) do
+    self:query(root, query, function(_, node, metadata)
         if metadata.conceal ~= nil then
             table.insert(nodes, node)
         end
-    end
+    end)
     return nodes
 end
 
@@ -101,7 +134,7 @@ local M = {}
 ---@param buf integer
 ---@param win integer
 function M.reset(buf, win)
-    cache[buf] = Context.new(buf, win)
+    cache[buf] = Context.new(buf, win, 10)
 end
 
 ---@param buf integer

Diff for: lua/render-markdown/extmark.lua

@@ -20,9 +20,7 @@ local M = {}
 function M.parse(root, buf)
     local config = state.get_config(buf)
     local marks = {}
-    local query = state.markdown_query
-    for id, node in query:iter_captures(root, buf) do
-        local capture = query.captures[id]
+    context.get(buf):query(root, state.markdown_query, function(capture, node)
         local info = ts.info(node, buf)
         logger.debug_node_info(capture, info)
         if capture == 'heading' then
@@ -38,23 +36,21 @@ function M.parse(root, buf)
         elseif capture == 'checkbox_checked' then
             list.add_mark(marks, M.checkbox(config, info, config.checkbox.checked))
         elseif capture == 'quote' then
-            local quote_query = state.markdown_quote_query
-            for nested_id, nested_node in quote_query:iter_captures(info.node, buf) do
-                local nested_capture = quote_query.captures[nested_id]
+            context.get(buf):query(info.node, state.markdown_quote_query, function(nested_capture, nested_node)
                 local nested_info = ts.info(nested_node, buf)
                 logger.debug_node_info(nested_capture, nested_info)
                 if nested_capture == 'quote_marker' then
                     list.add_mark(marks, M.quote_marker(config, nested_info, info))
                 else
                     logger.unhandled_capture('markdown quote', nested_capture)
                 end
-            end
+            end)
         elseif capture == 'table' then
             vim.list_extend(marks, M.pipe_table(config, buf, info))
         else
             logger.unhandled_capture('markdown', capture)
         end
-    end
+    end)
     return marks
 end