Add support for overlaying checkbox icons

# Details

Pulls in the checkbox replacement logic from PR:
#13

Updates documentation and demo. Slight change to agg font selection.

Co-Authored-By: Dmitriy <dmitriy@shabaev.com>

Author: MeanderingProgrammer

README.md

@@ -14,6 +14,7 @@ Plugin to improve viewing Markdown files in Neovim
 - Updates horizontal breaks with full-width lines
 - Highlights code blocks and inline code to better stand out
 - Replaces bullet points with provided character based on level
+- Replaces checkboxes with provided characters based on whether they are checked
 - Replaces block quote leading `>` with provided character
 - Updates table borders with better border characters, does NOT automatically align
 - Basic support for `LaTeX` if `pylatexenc` is installed on system
@@ -69,6 +70,9 @@ require('render-markdown').setup({
             (list_marker_star)
         ] @list_marker
 
+        (task_list_marker_unchecked) @checkbox_unchecked
+        (task_list_marker_checked) @checkbox_checked
+
         (block_quote (block_quote_marker) @quote_marker)
         (block_quote (paragraph (inline (block_continuation) @quote_marker)))
 
@@ -92,6 +96,12 @@ require('render-markdown').setup({
     dash = '—',
     -- Character to use for the bullet points in lists
     bullets = { '●', '○', '◆', '◇' },
+    checkbox = {
+        -- Character that will replace the [ ] in unchecked checkboxes
+        unchecked = '󰄱 ',
+        -- Character that will replace the [x] in checked checkboxes
+        checked = ' ',
+    },
     -- Character that will replace the > at the start of block quotes
     quote = '┃',
     -- See :h 'conceallevel' for more information about meaning of values
@@ -124,6 +134,12 @@ require('render-markdown').setup({
         code = 'ColorColumn',
         -- Bullet points in list
         bullet = 'Normal',
+        checkbox = {
+            -- Unchecked checkboxes
+            unchecked = '@markup.list.unchecked',
+            -- Checked checkboxes
+            checked = '@markup.heading',
+        },
         table = {
             -- Header of a markdown table
             head = '@markup.heading',

demo/demo.gif

@@ -33,6 +33,9 @@ if __name__ == "__main__":
 2. Item 2
 3. Item 3
 
+- [ ] Unchecked Checkbox
+- [x] Checked Checkbox
+
 ---
 
   > Quote line 1

demo/sample.md

@@ -1,4 +1,4 @@
-*render-markdown.txt*           For 0.9.5           Last change: 2024 April 11
+*render-markdown.txt*           For 0.9.5           Last change: 2024 April 13
 
 ==============================================================================
 Table of Contents                          *render-markdown-table-of-contents*
@@ -34,6 +34,7 @@ Plugin to improve viewing Markdown files in Neovim
 - Updates horizontal breaks with full-width lines
 - Highlights code blocks and inline code to better stand out
 - Replaces bullet points with provided character based on level
+- Replaces checkboxes with provided characters based on whether they are checked
 - Replaces block quote leading `>` with provided character
 - Updates table borders with better border characters, does NOT automatically align
 - Basic support for `LaTeX` if `pylatexenc` is installed on system
@@ -96,6 +97,9 @@ modified by the user.
                 (list_marker_star)
             ] @list_marker
 
+            (task_list_marker_unchecked) @checkbox_unchecked
+            (task_list_marker_checked) @checkbox_checked
+    
             (block_quote (block_quote_marker) @quote_marker)
             (block_quote (paragraph (inline (block_continuation) @quote_marker)))
 
@@ -119,6 +123,12 @@ modified by the user.
         dash = '—',
         -- Character to use for the bullet points in lists
         bullets = { '●', '○', '◆', '◇' },
+        checkbox = {
+            -- Character that will replace the [ ] in unchecked checkboxes
+            unchecked = '󰄱 ',
+            -- Character that will replace the [x] in checked checkboxes
+            checked = ' ',
+        },
         -- Character that will replace the > at the start of block quotes
         quote = '┃',
         -- See :h 'conceallevel' for more information about meaning of values
@@ -151,6 +161,12 @@ modified by the user.
             code = 'ColorColumn',
             -- Bullet points in list
             bullet = 'Normal',
+            checkbox = {
+                -- Unchecked checkboxes
+                unchecked = '@markup.list.unchecked',
+                -- Checked checkboxes
+                checked = '@markup.heading',
+            },
             table = {
                 -- Header of a markdown table
                 head = '@markup.heading',

doc/render-markdown.txt

@@ -1,4 +1,4 @@
-default_zoom := '3'
+default_zoom := '2'
 
 demo zoom=default_zoom:
     rm -f demo/demo.gif
@@ -8,7 +8,7 @@ demo zoom=default_zoom:
       --cast demo.cast
     # https://docs.asciinema.org/manual/agg/usage/
     agg demo.cast demo/demo.gif \
-      --font-family "JetBrainsMono NFM" \
+      --font-family "Monaspace Neon,Hack Nerd Font" \
       --last-frame-duration 1
     rm demo.cast
 

justfile

@@ -70,6 +70,24 @@ M.render = function(namespace, root)
                 virt_text = { virt_text },
                 virt_text_pos = 'overlay',
             })
+        elseif vim.tbl_contains({ 'checkbox_unchecked', 'checkbox_checked' }, capture) then
+            local checkbox = state.config.checkbox.unchecked
+            local highlight = highlights.checkbox.unchecked
+            if capture == 'checkbox_checked' then
+                checkbox = state.config.checkbox.checked
+                highlight = highlights.checkbox.checked
+            end
+            local padding = vim.fn.strdisplaywidth(value) - vim.fn.strdisplaywidth(checkbox)
+
+            if padding >= 0 then
+                local virt_text = { string.rep(' ', padding) .. checkbox, highlight }
+                vim.api.nvim_buf_set_extmark(0, namespace, start_row, start_col, {
+                    end_row = end_row,
+                    end_col = end_col,
+                    virt_text = { virt_text },
+                    virt_text_pos = 'overlay',
+                })
+            end
         elseif capture == 'table' then
             if state.config.fat_tables then
                 local lines = vim.api.nvim_buf_get_lines(0, start_row, end_row, false)

lua/render-markdown/handler/markdown.lua

@@ -7,6 +7,10 @@ local M = {}
 ---@field public head? string
 ---@field public row? string
 
+---@class UserCheckboxHighlights
+---@field public unchecked? string
+---@field public checked? string
+
 ---@class UserHeadingHighlights
 ---@field public backgrounds? string[]
 ---@field public foregrounds? string[]
@@ -16,6 +20,7 @@ local M = {}
 ---@field public dash? string
 ---@field public code? string
 ---@field public bullet? string
+---@field public checkbox? UserCheckboxHighlights
 ---@field public table? UserTableHighlights
 ---@field public latex? string
 ---@field public quote? string
@@ -24,6 +29,10 @@ local M = {}
 ---@field public default? integer
 ---@field public rendered? integer
 
+---@class UserCheckbox
+---@field public unchecked? string
+---@field public checked? string
+
 ---@class UserConfig
 ---@field public markdown_query? string
 ---@field public inline_query? string
@@ -32,6 +41,7 @@ local M = {}
 ---@field public headings? string[]
 ---@field public dash? string
 ---@field public bullets? string[]
+---@field public checkbox? UserCheckbox
 ---@field public quote? string
 ---@field public conceal? UserConceal
 ---@field public fat_tables? boolean
@@ -61,6 +71,9 @@ function M.setup(opts)
                 (list_marker_star)
             ] @list_marker
 
+            (task_list_marker_unchecked) @checkbox_unchecked
+            (task_list_marker_checked) @checkbox_checked
+
             (block_quote (block_quote_marker) @quote_marker)
             (block_quote (paragraph (inline (block_continuation) @quote_marker)))
 
@@ -77,6 +90,10 @@ function M.setup(opts)
         headings = { '󰲡 ', '󰲣 ', '󰲥 ', '󰲧 ', '󰲩 ', '󰲫 ' },
         dash = '—',
         bullets = { '●', '○', '◆', '◇' },
+        checkbox = {
+            unchecked = '󰄱 ',
+            checked = ' ',
+        },
         quote = '┃',
         conceal = {
             default = vim.opt.conceallevel:get(),
@@ -98,6 +115,10 @@ function M.setup(opts)
             dash = 'LineNr',
             code = 'ColorColumn',
             bullet = 'Normal',
+            checkbox = {
+                unchecked = '@markup.list.unchecked',
+                checked = '@markup.heading',
+            },
             table = {
                 head = '@markup.heading',
                 row = 'Normal',

lua/render-markdown/init.lua

@@ -2,6 +2,10 @@
 ---@field public head string
 ---@field public row string
 
+---@class CheckboxHighlights
+---@field public unchecked string
+---@field public checked string
+
 ---@class HeadingHighlights
 ---@field public backgrounds string[]
 ---@field public foregrounds string[]
@@ -11,6 +15,7 @@
 ---@field public dash string
 ---@field public code string
 ---@field public bullet string
+---@field public checkbox CheckboxHighlights
 ---@field public table TableHighlights
 ---@field public latex string
 ---@field public quote string
@@ -19,6 +24,10 @@
 ---@field public default integer
 ---@field public rendered integer
 
+---@class Checkbox
+---@field public unchecked string
+---@field public checked string
+
 ---@class Config
 ---@field public markdown_query string
 ---@field public inline_query string
@@ -27,6 +36,7 @@
 ---@field public headings string[]
 ---@field public dash string
 ---@field public bullets string[]
+---@field public checkbox Checkbox
 ---@field public quote string
 ---@field public conceal Conceal
 ---@field public fat_tables boolean