Markdown to PDF (CJK)

Convert Markdown files to well-formatted PDF with full CJK (Chinese/Japanese/Korean) support, code blocks, and tables.

Toolchain

• Rendering engine: WeasyPrint (pre-installed, /usr/local/bin/weasyprint)
• Fonts: Noto Sans CJK SC / Noto Serif CJK SC (system-installed)
• Pipeline: Markdown → HTML (emoji replacement) → WeasyPrint → PDF

Steps

1. Emoji Processing

WeasyPrint does not render emoji characters. Replace them with text labels:

emoji_map = {
    '🦞': '[Lobster]', '🌅': '[Morning]', '🌙': '[Moon]', '🏛': '[Architecture]',
    '🔧': '[Tool]', '🔄': '[Restart]', '📰': '[Report]', '💪': '[Strong]',
    '⚡': '[Lightning]', '⏰': '[Alarm]', '👆': '[Up]', '⬆️': '[Up]',
    '🌟': '[Star]', '👇': '[Down]', '✅': '[Done]', '📊': '[Chart]',
    '🎯': '[Target]', '💡': '[Idea]', '🧰': '[Toolbox]', '🤖': '[AI]',
    '🏗️': '[Build]', '📅': '[Calendar]', '🧘': '[Meditation]', '📖': '[Read]',
    '📝': '[Note]', '🏃': '[Run]', '⭐': '[Fav]', '📬': '[Mail]',
    '🌐': '[Web]', '🐙': '[GitHub]', '💬': '[Chat]', '▪': '·',
    '❌': '[X]', '⚠️': '[!]', '📌': '[PIN]', '🔔': '[Bell]',
    '🤔': '[Think]', '😂': '[Laugh]', '🔒': '[Lock]', '📁': '[Folder]',
    '💰': '[Money]', '👨‍👧‍👦': '[Family]', '😴': '[Sleep]', '👶': '[Baby]',
    '1️⃣': '1.', '2️⃣': '2.', '3️⃣': '3.', '4️⃣': '4.', '5️⃣': '5.',
}

For emoji not in the map, strip variant selectors (\ufe0f) and replace with [?]. Preserve CJK punctuation marks (·…——''""etc.).

2. Markdown → HTML Conversion

Lightweight conversion using Python regex (no extra dependencies):

import re
html = md_content
html = re.sub(r'^# (.+)$', r'\x3Ch1>\1\x3C/h1>', html, flags=re.MULTILINE)
html = re.sub(r'^## (.+)$', r'\x3Ch2>\1\x3C/h2>', html, flags=re.MULTILINE)
html = re.sub(r'^### (.+)$', r'\x3Ch3>\1\x3C/h3>', html, flags=re.MULTILINE)
html = re.sub(r'\*\*(.+?)\*\*', r'\x3Cstrong>\1\x3C/strong>', html)
html = re.sub(r'\*(.+?)\*', r'\x3Cem>\1\x3C/em>', html)
html = re.sub(r'^> (.+)$', r'\x3Cblockquote>\1\x3C/blockquote>', html, flags=re.MULTILINE)
html = re.sub(r'^---$', r'\x3Chr/>', html, flags=re.MULTILINE)
html = re.sub(r'^- (.+)$', r'\x3Cli>\1\x3C/li>', html, flags=re.MULTILINE)
html = re.sub(r'`([^`]+)`', r'\x3Ccode>\1\x3C/code>', html)
html = re.sub(r'```(\w*)\
(.*?)```', r'\x3Cpre>\x3Ccode>\2\x3C/code>\x3C/pre>', html, flags=re.DOTALL)
# Paragraphs
html = re.sub(r'\
\
', r'\x3C/p>\x3Cp>', html)
html = '\x3Cp>' + html + '\x3C/p>'
# Clean empty tags
html = re.sub(r'\x3Cp>\s*\x3C/p>', '', html)
html = re.sub(r'\x3Cp>\s*(\x3Ch[123]>.*?\x3C/h[123]>)\s*\x3C/p>', r'\1', html, flags=re.DOTALL)
html = re.sub(r'\x3Cp>\s*(\x3Chr/>)\s*\x3C/p>', r'\1', html)
html = re.sub(r'\x3Cp>\s*(\x3Cblockquote>.*?\x3C/blockquote>)\s*\x3C/p>', r'\1', html, flags=re.DOTALL)

3. HTML Template

\x3C!DOCTYPE html>
\x3Chtml>
\x3Chead>
\x3Cmeta charset="utf-8">
\x3Cstyle>
@page { size: A4; margin: 2cm 2.5cm 2cm 2.5cm; }
body {
    font-family: "Noto Sans CJK SC", "Noto Serif CJK SC", sans-serif;
    font-size: 11pt; line-height: 1.8; color: #333;
    max-width: 100%; word-wrap: break-word;
}
h1 { font-size: 20pt; color: #d32f2f; border-bottom: 2px solid #d32f2f; padding-bottom: 8px; margin-top: 30px; }
h2 { font-size: 15pt; color: #333; margin-top: 25px; border-left: 4px solid #d32f2f; padding-left: 10px; }
h3 { font-size: 13pt; color: #555; margin-top: 20px; }
blockquote { border-left: 3px solid #ccc; padding-left: 15px; color: #666; margin: 15px 0; font-style: italic; }
code { background: #f5f5f5; padding: 2px 6px; border-radius: 3px; font-size: 10pt; }
pre { background: #f8f8f8; padding: 12px; border-radius: 5px; font-size: 9.5pt; line-height: 1.6; }
pre code { background: none; padding: 0; }
strong { color: #d32f2f; }
hr { border: none; border-top: 1px solid #ddd; margin: 25px 0; }
li { margin: 5px 0; }
table { border-collapse: collapse; width: 100%; margin: 15px 0; }
th, td { border: 1px solid #ddd; padding: 8px 12px; text-align: left; }
th { background: #f5f5f5; font-weight: bold; }
\x3C/style>
\x3C/head>
\x3Cbody>{{HTML_CONTENT}}\x3C/body>
\x3C/html>

4. Generate PDF

weasyprint /tmp/input.html /tmp/output.pdf

One-line Script

All steps are wrapped into a single script:

#!/bin/bash
# Usage: md2pdf.sh input.md [output.pdf]
# Markdown → PDF (weasyprint + CJK + emoji replacement)
INPUT="${1:-/dev/stdin}"
OUTPUT="${2:-/tmp/output.pdf}"
python3 /path/to/md2pdf.py "$INPUT" "$OUTPUT"

Important Notes

• Do NOT use pandoc + xelatex: Emoji renders as blank, and compilation is slow
• Do NOT use pandoc + wkhtmltopdf: Not installed by default
• Always use WeasyPrint: The only solution that supports CJK + emoji replacement
• Output path: Always use absolute paths under /tmp/
• Pre-send check: Verify PDF file exists and is > 10KB before sending