feat: inline render single line latex equations

## Details

Request: #508

The request for inline rendering latex has been around for a while, and
is one I haven't implemented due to the difficulty of aligning
multi-line outputs with inputs and handling multiple formulas on the
same line.

However when the output of the converter is a single line, we can
essentially ignore all of this and use an inline / conceal `extmark` to
overlay our content instead of the raw formula.

This is the new default behavior out of the box and will apply to anyone
using latex support through this plugin. A new option has been added
`latex.virtual` that when set to `true` forces the plugin to always use
virtual lines rather than trying to inline, which replicates the old
behavior of this plugin.

Co-authored-by: Lexey Khom <92052116+LexeyKhom@users.noreply.github.com>

Author: MeanderingProgrammer

CHANGELOG.md

@@ -16,6 +16,13 @@
 - prioritize hide over highlight_border [7b37aab](https://github.com/MeanderingProgrammer/render-markdown.nvim/commit/7b37aaba005df5744fc7a6bd4225983576b2a950)
 - add option to restart treesitter highlighter to clear invalid state [#488](https://github.com/MeanderingProgrammer/render-markdown.nvim/issues/488)
   [ec74afa](https://github.com/MeanderingProgrammer/render-markdown.nvim/commit/ec74afa498b6ce3ee686131adf2b3941b713f307)
+- use display width for latex formula alignment [c4ff9ac](https://github.com/MeanderingProgrammer/render-markdown.nvim/commit/c4ff9acddcf0f79b3187393319adb5cac5865bd3)
+- anti-conceal ignore modes [8074a9c](https://github.com/MeanderingProgrammer/render-markdown.nvim/commit/8074a9cc9a6f737320b7a0d76b2c4c3485155688)
+- component level render modes [84d4928](https://github.com/MeanderingProgrammer/render-markdown.nvim/commit/84d4928cb4b508847294002835989880da4ce13b)
+
+### Collaborator Shoutouts
+
+- @LexeyKhom
 
 ## 8.7.0 (2025-08-08)
 

README.md

@@ -297,6 +297,8 @@ require('render-markdown').setup({
         top_pad = 0,
         -- Number of empty lines below latex blocks.
         bottom_pad = 0,
+        -- Always use virtual lines for rendering instead of attempting to inline.
+        virtual = false,
     },
     on = {
         -- Called when plugin initially attaches to a buffer.

doc/render-markdown.txt

@@ -363,6 +363,8 @@ Default Configuration ~
             top_pad = 0,
             -- Number of empty lines below latex blocks.
             bottom_pad = 0,
+            -- Always use virtual lines for rendering instead of attempting to inline.
+            virtual = false,
         },
         on = {
             -- Called when plugin initially attaches to a buffer.

lua/render-markdown/config/latex.lua

@@ -4,6 +4,7 @@
 ---@field position render.md.latex.Position
 ---@field top_pad integer
 ---@field bottom_pad integer
+---@field virtual boolean
 
 ---@enum render.md.latex.Position
 local Position = {
@@ -32,6 +33,8 @@ M.default = {
     top_pad = 0,
     -- Number of empty lines below latex blocks.
     bottom_pad = 0,
+    -- Always use virtual lines for rendering instead of attempting to inline.
+    virtual = false,
 }
 
 ---@param spec render.md.debug.ValidatorSpec
@@ -42,6 +45,7 @@ function M.validate(spec)
     spec:one_of('position', vim.tbl_values(Position))
     spec:type('top_pad', 'number')
     spec:type('bottom_pad', 'number')
+    spec:type('virtual', 'boolean')
     spec:check()
 end
 

lua/render-markdown/handler/latex.lua

@@ -39,49 +39,48 @@ function Handler:run(root)
     local node = Node.new(self.context.buf, root)
     log.node('latex', node)
 
-    local indent = self:indent(node.start_row, node.start_col)
-    local lines = iter.list.map(self:expressions(node), function(expression)
-        local line = vim.list_extend({}, indent) ---@type render.md.mark.Line
-        line[#line + 1] = { expression, self.config.highlight }
-        return line
-    end)
-
-    local above = self.config.position == 'above'
-    local row = above and node.start_row or node.end_row
-
     local marks = Marks.new(self.context, true)
-    marks:add(self.config, 'virtual_lines', row, 0, {
-        virt_lines = lines,
-        virt_lines_above = above,
-    })
-    return marks:get()
-end
-
----@private
----@param node render.md.Node
----@return string[]
-function Handler:expressions(node)
-    local col = node.start_col
-    local _, first = node:line('first', 0)
-    local prefix = str.pad(first and str.width(first:sub(1, col)) or col)
-
-    local result = {} ---@type string[]
-    for _ = 1, self.config.top_pad do
-        result[#result + 1] = ''
-    end
-
-    local lines = str.split(self:convert(node.text), '\n', true)
-    local width = vim.fn.max(iter.list.map(lines, str.width))
-    for _, line in ipairs(lines) do
-        local suffix = str.pad(width - str.width(line))
-        result[#result + 1] = prefix .. line .. suffix
-    end
+    local output = str.split(self:convert(node.text), '\n', true)
+    if self.config.virtual or #output > 1 then
+        local col = node.start_col
+        local _, first = node:line('first', 0)
+        local prefix = str.pad(first and str.width(first:sub(1, col)) or col)
+        local width = vim.fn.max(iter.list.map(output, str.width))
+
+        local text = {} ---@type string[]
+        for _ = 1, self.config.top_pad do
+            text[#text + 1] = ''
+        end
+        for _, line in ipairs(output) do
+            local suffix = str.pad(width - str.width(line))
+            text[#text + 1] = prefix .. line .. suffix
+        end
+        for _ = 1, self.config.bottom_pad do
+            text[#text + 1] = ''
+        end
 
-    for _ = 1, self.config.bottom_pad do
-        result[#result + 1] = ''
+        local indent = self:indent(node.start_row, col)
+        local lines = iter.list.map(text, function(part)
+            local line = vim.list_extend({}, indent) ---@type render.md.mark.Line
+            line[#line + 1] = { part, self.config.highlight }
+            return line
+        end)
+
+        local above = self.config.position == 'above'
+        local row = above and node.start_row or node.end_row
+
+        marks:add(self.config, 'virtual_lines', row, 0, {
+            virt_lines = lines,
+            virt_lines_above = above,
+        })
+    else
+        marks:over(self.config, true, node, {
+            virt_text = { { output[1], self.config.highlight } },
+            virt_text_pos = 'inline',
+            conceal = '',
+        })
     end
-
-    return result
+    return marks:get()
 end
 
 ---@private

lua/render-markdown/health.lua

@@ -5,7 +5,7 @@ local state = require('render-markdown.state')
 local M = {}
 
 ---@private
-M.version = '8.7.12'
+M.version = '8.7.13'
 
 function M.check()
     M.start('versions')

lua/render-markdown/types.lua

@@ -197,6 +197,7 @@
 ---@field position? render.md.latex.Position
 ---@field top_pad? integer
 ---@field bottom_pad? integer
+---@field virtual? boolean
 
 ---@class (exact) render.md.link.UserConfig: render.md.base.UserConfig
 ---@field footnote? render.md.link.footnote.UserConfig

tests/latex_spec.lua

@@ -13,27 +13,11 @@ local function set_responses(converter, responses)
     stub.new(vim.fn, 'system', function(cmd, input)
         assert.same(converter, cmd)
         local result = responses[input]
-        assert.is_true(result ~= nil, 'No output for: ' .. input)
+        assert.is_true(result ~= nil, 'missing output for: ' .. input)
         return result
     end)
 end
 
----@param lines string[]
----@param width integer
----@return vim.api.keyset.set_extmark
-local function latex(lines, width)
-    local virt_lines = vim.iter(lines)
-        :map(function(line)
-            return { { line .. (' '):rep(width - #line), 'RmMath' } }
-        end)
-        :totable()
-    ---@type vim.api.keyset.set_extmark
-    return {
-        virt_lines = virt_lines,
-        virt_lines_above = true,
-    }
-end
-
 ---@param lines string[]
 ---@param prefix string
 ---@param suffix string
@@ -71,14 +55,24 @@ describe('latex.md', function()
         marks:add(row:get(0, 0), { 0, 1 }, util.heading.icon(1))
         marks:add(row:get(0, 1), { 0, 0 }, util.heading.bg(1))
 
-        marks:add(row:get(1), 0, latex(inline.out, 17))
-        marks:add(row:get(2), 0, latex(block.out, 28))
+        marks:add(row:get(1, 0), { 0, 21 }, {
+            virt_text = { { inline.out[1], 'RmMath' } },
+            virt_text_pos = 'inline',
+            conceal = '',
+        })
+        marks:add(row:get(2), 0, {
+            virt_lines = vim.iter(block.out)
+                :map(function(line)
+                    return { { line .. (' '):rep(28 - #line), 'RmMath' } }
+                end)
+                :totable(),
+            virt_lines_above = true,
+        })
 
         util.assert_view(marks, {
             '󰫎 󰲡 LaTeX',
             '',
             '  ' .. inline.out[1],
-            '  ' .. inline.raw[1],
             '',
             '  ' .. block.out[1],
             '  ' .. block.out[2],