Book Publishing

Why LuaLaTeX: Native Unicode support (XeLaTeX works but LuaLaTeX handles emoji processing more reliably with Lua filters).

Emoji Handling (Critical)

The ZWJ Problem

Zero Width Joiner (ZWJ) sequences combine multiple emoji into one glyph. Sort order is critical:

CRITICAL RULE: The emoji replacement map MUST be sorted by length descending (longest sequences first). If you process 👨 before 👨‍👩‍👧‍👦, the family emoji gets partially replaced and corrupts the output.

Emoji Map File

Create an explicit emoji-map.json that controls all replacements:

{
  "metadata": {
    "version": "1.0",
    "source": "Twemoji",
    "sortOrder": "length-descending"
  },
  "emojis": [
    {
      "sequence": "👨‍👩‍👧‍👦",
      "codepoints": "1f468-200d-1f469-200d-1f467-200d-1f466",
      "image": "1f468-200d-1f469-200d-1f467-200d-1f466.png",
      "length": 7
    }
  ]
}

Rule: Never rely on automatic emoji detection. Use an explicit map file that you control and sort.

Twemoji Base64 Embedding

Embed Twemoji images directly as base64 in the LaTeX output to avoid external file dependencies:

-- Pandoc Lua filter for emoji replacement
function Str(elem)
  -- Process emoji map (length-descending order)
  for _, entry in ipairs(emoji_map) do
    if elem.text:find(entry.sequence) then
      local img = pandoc.Image("", entry.base64_data_uri)
      -- Set size to match surrounding text
      img.attributes.height = "1em"
      return img
    end
  end
end

Windows Emoji Limitation

Windows cannot natively render flag emoji (🇺🇸, 🇬🇧, etc.) in many contexts. Solutions:

Rule: Always preview emoji-heavy content in the PDF output, not in the editor.

Dual PDF Configuration

Print Edition

# pandoc-print.yaml
pdf-engine: lualatex