feature: Support left padding code blocks

# Details

Add 'left_pad' parameter to code configuration, default to 0.

Left padding requires 0.10.0. Use a footnote to identify features
gated on the 0.10.0 version.

Minor bug fix to padded cell type, subtract one of end col.

Author: MeanderingProgrammer

Diff for: README.md

@@ -19,21 +19,23 @@ Plugin to improve viewing Markdown files in Neovim
   - Headings: highlight depending on level and replaces `#` with icon
   - Horizontal breaks: replace with full-width lines
   - Code blocks: highlight to better stand out
-    - Adds language icon, requires icon provider (`mini.icons` or `nvim-web-devicons`)
-      and neovim >= `0.10.0`
+    - Adds language icon [^1], requires icon provider (`mini.icons` or `nvim-web-devicons`)
+    - Left pad lines within block [^1]
   - Inline code: highlight to better stand out
   - List bullet points: replace with provided icon based on level
   - Checkboxes: replace with provided icon based on whether they are checked
   - Block quotes: replace leading `>` with provided icon
   - Tables: replace border characters, does NOT automatically align
   - [Callouts](https://github.com/orgs/community/discussions/16925)
     - Github & Obsidian out of the box, supports user defined as well
-  - Custom checkbox states, function similar to `callouts`
-  - Adds icon before images / links, requires neovim >= `0.10.0`
+  - Custom checkbox states [^1], function similar to `callouts`
+  - Adds icon before images / links [^1]
   - `LaTeX` blocks: renders formulas if `latex` parser and `pylatexenc` are installed
 - Disable rendering when file is larger than provided value
 - Support custom handlers which are ran identically to builtin handlers
 
+[^1]: Requires neovim >= `0.10.0`
+
 # Requirements
 
 - neovim `>= 0.9.0` (minimum) `>= 0.10.0` (recommended)
@@ -206,10 +208,12 @@ require('render-markdown').setup({
         sign = true,
         -- Determines how code blocks & inline code are rendered:
         --  none: disables all rendering
-        --  normal: adds highlight group to code blocks & inline code
+        --  normal: adds highlight group to code blocks & inline code, adds padding to code blocks
         --  language: adds language icon to sign column if enabled and icon + name above code blocks
         --  full: normal + language
         style = 'full',
+        -- Amount of padding to add to the left of code blocks
+        left_pad = 0,
         -- Determins how the top / bottom of code block are rendered:
         --  thick: use the same highlight as the code body
         --  thin: when lines are empty overlay the above & below icons
@@ -426,10 +430,12 @@ require('render-markdown').setup({
         sign = true,
         -- Determines how code blocks & inline code are rendered:
         --  none: disables all rendering
-        --  normal: adds highlight group to code blocks & inline code
+        --  normal: adds highlight group to code blocks & inline code, adds padding to code blocks
         --  language: adds language icon to sign column if enabled and icon + name above code blocks
         --  full: normal + language
         style = 'full',
+        -- Amount of padding to add to the left of code blocks
+        left_pad = 0,
         -- Determins how the top / bottom of code block are rendered:
         --  thick: use the same highlight as the code body
         --  thin: when lines are empty overlay the above & below icons

Diff for: doc/render-markdown.txt

@@ -48,17 +48,17 @@ Plugin to improve viewing Markdown files in Neovim
     - Headings: highlight depending on level and replaces `#` with icon
     - Horizontal breaks: replace with full-width lines
     - Code blocks: highlight to better stand out
-        - Adds language icon, requires icon provider (`mini.icons` or `nvim-web-devicons`)
-            and neovim >= `0.10.0`
+        - Adds language icon , requires icon provider (`mini.icons` or `nvim-web-devicons`)
+        - Left pad lines within block 
     - Inline code: highlight to better stand out
     - List bullet points: replace with provided icon based on level
     - Checkboxes: replace with provided icon based on whether they are checked
     - Block quotes: replace leading `>` with provided icon
     - Tables: replace border characters, does NOT automatically align
     - Callouts <https://github.com/orgs/community/discussions/16925>
         - Github & Obsidian out of the box, supports user defined as well
-    - Custom checkbox states, function similar to `callouts`
-    - Adds icon before images / links, requires neovim >= `0.10.0`
+    - Custom checkbox states , function similar to `callouts`
+    - Adds icon before images / links 
     - `LaTeX` blocks: renders formulas if `latex` parser and `pylatexenc` are installed
 - Disable rendering when file is larger than provided value
 - Support custom handlers which are ran identically to builtin handlers
@@ -244,10 +244,12 @@ Full Default Configuration ~
             sign = true,
             -- Determines how code blocks & inline code are rendered:
             --  none: disables all rendering
-            --  normal: adds highlight group to code blocks & inline code
+            --  normal: adds highlight group to code blocks & inline code, adds padding to code blocks
             --  language: adds language icon to sign column if enabled and icon + name above code blocks
             --  full: normal + language
             style = 'full',
+            -- Amount of padding to add to the left of code blocks
+            left_pad = 0,
             -- Determins how the top / bottom of code block are rendered:
             --  thick: use the same highlight as the code body
             --  thin: when lines are empty overlay the above & below icons
@@ -464,10 +466,12 @@ CODE BLOCKS                                *render-markdown-setup-code-blocks*
             sign = true,
             -- Determines how code blocks & inline code are rendered:
             --  none: disables all rendering
-            --  normal: adds highlight group to code blocks & inline code
+            --  normal: adds highlight group to code blocks & inline code, adds padding to code blocks
             --  language: adds language icon to sign column if enabled and icon + name above code blocks
             --  full: normal + language
             style = 'full',
+            -- Amount of padding to add to the left of code blocks
+            left_pad = 0,
             -- Determins how the top / bottom of code block are rendered:
             --  thick: use the same highlight as the code body
             --  thin: when lines are empty overlay the above & below icons

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

@@ -168,6 +168,19 @@ M.render_code = function(namespace, buf, info)
         hl_group = code.highlight,
         hl_eol = true,
     })
+    -- Requires inline extmarks
+    if not util.has_10 or code.left_pad <= 0 then
+        return
+    end
+    for row = start_row, end_row - 1 do
+        -- Uses a low priority so other marks are loaded first and included in padding
+        vim.api.nvim_buf_set_extmark(buf, namespace, row, info.start_col, {
+            end_row = row + 1,
+            priority = 0,
+            virt_text = { { str.pad('', code.left_pad), code.highlight } },
+            virt_text_pos = 'inline',
+        })
+    end
 end
 
 ---@private
@@ -402,7 +415,7 @@ M.render_table_row = function(namespace, buf, row, highlight)
                 if pipe_table.cell == 'padded' and util.has_10 then
                     local offset = M.table_visual_offset(buf, cell)
                     if offset > 0 then
-                        vim.api.nvim_buf_set_extmark(buf, namespace, cell.start_row, cell.end_col, {
+                        vim.api.nvim_buf_set_extmark(buf, namespace, cell.start_row, cell.end_col - 1, {
                             virt_text = { { str.pad('', offset), pipe_table.filler } },
                             virt_text_pos = 'inline',
                         })

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

@@ -60,6 +60,7 @@ local M = {}
 ---@field public enabled? boolean
 ---@field public sign? boolean
 ---@field public style? 'full'|'normal'|'language'|'none'
+---@field public left_pad? integer
 ---@field public border? 'thin'|'thick'
 ---@field public above? string
 ---@field public below? string
@@ -212,10 +213,12 @@ M.default_config = {
         sign = true,
         -- Determines how code blocks & inline code are rendered:
         --  none: disables all rendering
-        --  normal: adds highlight group to code blocks & inline code
+        --  normal: adds highlight group to code blocks & inline code, adds padding to code blocks
         --  language: adds language icon to sign column if enabled and icon + name above code blocks
         --  full: normal + language
         style = 'full',
+        -- Amount of padding to add to the left of code blocks
+        left_pad = 0,
         -- Determins how the top / bottom of code block are rendered:
         --  thick: use the same highlight as the code body
         --  thin: when lines are empty overlay the above & below icons

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

@@ -113,6 +113,7 @@ function state.validate()
         enabled = { code.enabled, 'boolean' },
         sign = { code.sign, 'boolean' },
         style = one_of(code.style, { 'full', 'normal', 'language', 'none' }),
+        left_pad = { code.left_pad, 'number' },
         border = one_of(code.border, { 'thin', 'thick' }),
         above = { code.above, 'string' },
         below = { code.below, 'string' },

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

@@ -53,6 +53,7 @@
 ---@field public enabled boolean
 ---@field public sign boolean
 ---@field public style 'full'|'normal'|'language'|'none'
+---@field public left_pad integer
 ---@field public border 'thin'|'thick'
 ---@field public above string
 ---@field public below string

Diff for: tests/list_table_spec.lua

@@ -31,22 +31,22 @@ async_tests.describe('list_table.md', function()
             util.table_pipe(19, 0, true), -- Heading pipe 1
             util.table_border(19, 'above', { 18, 20 }),
             util.inline_code(19, 2, 18), -- Inline code in heading
-            util.table_padding(19, 19, 2), -- Heading padding 1
+            util.table_padding(19, 18, 2), -- Heading padding 1
             util.table_pipe(19, 19, true), -- Heading pipe 2
-            util.table_padding(19, 40, 2), -- Heading padding 2
+            util.table_padding(19, 39, 2), -- Heading padding 2
             util.table_pipe(19, 40, true), -- Heading pipe 2
             util.table_border(20, 'delimiter', { 18, 20 }),
             util.table_pipe(21, 0, false), -- Row 1 pipe 1
             util.table_pipe(21, 19, false), -- Row 1 pipe 2
-            util.table_padding(21, 40, 4), -- Row 1 padding 2
+            util.table_padding(21, 39, 4), -- Row 1 padding 2
             util.table_pipe(21, 40, false), -- Row 1 pipe 3
             util.table_pipe(22, 0, false), -- Row 2 pipe 1
             util.table_border(22, 'below', { 18, 20 }),
             util.inline_code(22, 2, 15), -- Row 2 inline code
-            util.table_padding(22, 19, 2), -- Row 2 padding 1
+            util.table_padding(22, 18, 2), -- Row 2 padding 1
             util.table_pipe(22, 19, false), -- Row 2 pipe 2
             util.link(22, 21, 39, false), -- Row 2 link
-            util.table_padding(22, 40, 7), -- Row 2 padding 2
+            util.table_padding(22, 39, 7), -- Row 2 padding 2
             util.table_pipe(22, 40, false), -- Row 2 pipe 3
         })
 

Diff for: tests/table_spec.lua

@@ -14,16 +14,16 @@ async_tests.describe('table.md', function()
             util.table_border(2, 'above', { 11, 24 }),
             util.table_pipe(2, 12, true), -- Heading pipe 2
             util.inline_code(2, 14, 25), -- Inline code in heading
-            util.table_padding(2, 37, 2), -- Heading padding 2
+            util.table_padding(2, 36, 2), -- Heading padding 2
             util.table_pipe(2, 37, true), -- Heading pipe 3
             util.table_border(3, 'delimiter', { 11, 24 }),
             util.table_pipe(4, 0, false), -- Row pipe 1
             util.table_border(4, 'below', { 11, 24 }),
             util.inline_code(4, 2, 12), -- Row inline code
-            util.table_padding(4, 13, 2), -- Row padding 1
+            util.table_padding(4, 12, 2), -- Row padding 1
             util.table_pipe(4, 13, false), -- Row pipe 2
             util.link(4, 15, 38, false), -- Row link
-            util.table_padding(4, 39, 16), -- Row padding 2
+            util.table_padding(4, 38, 16), -- Row padding 2
             util.table_pipe(4, 39, false), -- Row pipe 3
         })