Professional PDF Book Exporter: Export Hugo Markdown Books to PDF

In the field of content creation, especially for technical documentation and eBooks, Hugo has become a top choice for many technical writers due to its speed and powerful features. However, exporting Hugo book content to high-quality PDF files has always been a challenge. In this article, I share my experience developing PDF Book Exporter, a tool that converts Hugo book content into professional-grade PDF documents.

Note

The PDF export tool is open source. Visit GitHub for more information.

Recently, I updated my Kubernetes Handbook and exported it to PDF using this tool. The results are impressive. You can download Kubernetes Handbook v2025.08.04 PDF from the release page.

Screenshot of Kubernetes Handbook PDF exported with PDF Book Exporter

The main purpose of developing this tool was to quickly generate PDF documents and to facilitate book archiving on my website.

Why Do You Need a Professional PDF Export Tool?

While Hugo excels at generating web content, converting it to PDF format presents many challenges:

Complex Layouts: Web layouts differ fundamentally from print layouts
Multilingual Support: Proper rendering of CJK characters (Chinese, Japanese, Korean)
Emoji Rendering: Displaying colorful emoji in PDFs
Math Formulas: Correct handling of LaTeX math formulas
Code Highlighting: Syntax highlighting for programming languages
Table of Contents: Preserving Hugo book chapter structure and order
Image Processing: Supporting various image formats and optimization
Cover Design: Professional cover and back cover support

Simple web-to-PDF tools (like Chrome print or CSS-based renderers) often fall short for these complex needs. Markdown editors like Typora or web-based tools also lack advanced style control. That’s why I developed this Python, Pandoc, and LuaLaTeX-based PDF export tool.

PDF Book Exporter Overview

PDF Book Exporter is designed specifically for Hugo books, featuring:

📚 Hugo Book Structure Support - Automatically processes _index.md and index.md, sorts chapters by weight
🌍 Multilingual Support - Handles CJK characters, auto-detects system fonts
🎉 Emoji Rendering - Full Unicode emoji support with color font rendering
💻 Code Highlighting - 20+ languages supported via Pygments
📊 Table Optimization - Smart line wrapping and formatting
🖼️ Image Processing - Handles SVG, WebP, remote images, and more
🎨 Custom Styles - Customizable cover, back cover, color themes, and fonts
⚡ Smart Caching - Image processing cache for faster repeated exports

Technical Implementation

Core Architecture

PDF Book Exporter’s workflow:

Directory Scanning: Recursively scans Hugo book structure
Metadata Parsing: Reads front matter from each chapter
Content Merging: Merges chapters by weight order
Image Processing: Downloads and converts remote images
Pandoc Conversion: Processes content with Lua filter chain
LaTeX Compilation: Generates the final PDF

Lua Filter System

A series of Lua filters process content:

ansi-cleanup.lua: Cleans ANSI escape codes
fix-lstinline.lua: Fixes inline code styles
emoji-passthrough.lua: Handles emoji characters
minted-filter.lua: Syntax highlighting
cleanup-filter.lua: Cleans formatting issues
symbol-fallback-filter.lua: Symbol fallback
table-wrap.lua: Table wrapping optimization

Fonts and Emoji Handling

To support multilingual and emoji rendering:

Font Auto-Detection: Prefers high-quality CJK fonts (e.g., Source Han Sans SC, Noto Sans CJK SC)
Emoji Font Chain: Uses Apple Color Emoji or Noto Color Emoji for colorful emoji
LuaLaTeX Engine: Better Unicode and font chain support than XeLaTeX

Usage

Install Dependencies

# Install Pandoc
brew install pandoc

# Install LaTeX distribution (MacTeX)
brew install --cask mactex

# Install Pygments (code highlighting)
pip install Pygments

Basic Usage

# Export PDF
python cli.py content/zh/book/example -o output.pdf

# Enable emoji support
python cli.py content/zh/book/example -o output.pdf --emoji

# Generate summary
python cli.py content/zh/book/example --generate-summary

# Example directory
python cli.py tools/pdf-book-exporter/example -o example-book.pdf --emoji

Advanced Configuration

Configure the following in your book’s _index.md:

---
title: "My Professional Book"
book:
  title: "Full Book Title"
  author: "Author Name"
  date: "2025-08-05"
  description: "Book description"
  language: "en"
  cover: "cover.jpg"
  website: "https://example.com"
  subject: "Technical Documentation"
  keywords: "Hugo, PDF, Export"
---

Image Processing Details

PDF Book Exporter offers powerful image processing, automatically handling various formats.

Supported Image Formats

SVG: Automatically converted to PNG
WebP: Automatically converted to PNG
GIF: First frame extracted
Remote Images: Downloaded and cached

Image Processing Workflow

def process_images_in_content(content, book_dir, temp_dir, temp_pngs, current_file_path, cache_dir=None):
    # 1. Find image files
    abs_path = find_image_file_recursive(book_dir, img_path, current_file_path)
    
    # 2. Check cache
    if cache_dir:
        cached_path = get_cached_image(source_path, cache_dir, target_extension)
    
    # 3. Format conversion
    if ext == '.svg':
        convert_svg_to_png(source_path, output_dir, cache_dir)
    elif ext == '.webp':
        convert_webp_to_png(source_path, output_dir, cache_dir)

SVG to PNG Conversion

SVG is a vector format and may not render well in PDFs, so it’s converted to PNG using headless Chrome:

# Convert SVG to PNG with headless Chrome on macOS
/Applications/Google\ Chrome.app/Contents/MacOS/Google\ Chrome --headless --disable-gpu --screenshot=output.png input.svg

WebP to PNG Conversion

WebP is modern but unsupported by LaTeX, so it’s converted to PNG:

# Convert WebP to PNG with ImageMagick
magick input.webp output.png

Remote Image Handling

The tool automatically downloads and caches remote images:

Download to temp directory
Convert format if needed
Save to cache for reuse

Cover and Back Cover Settings

PDF Book Exporter supports highly customizable cover and back cover designs.

Cover Configuration

Configure cover parameters in _index.md:

---
title: "My Professional Book"
book:
  # Cover image
  cover: "cover.jpg"
  
  # Cover text
  cover_title_text: "PDF Export Feature Test"
  cover_author_text: "Author Name"
  cover_subtitle_text: "Book Subtitle"
  
  # Cover colors
  cover_title_color: "#FFFFFF"
  cover_author_color: "#E0E0E0"
  cover_subtitle_color: "#C0C0C0"
  
  # Font sizes
  cover_title_font_size: 42
  cover_author_font_size: 28
  cover_subtitle_font_size: 20
  
  # Text positions
  cover_title_position: "center"
  cover_author_position: "bottom"
  
  # Visual effects
  cover_overlay_enabled: true
  cover_text_shadow: false
---

Back Cover Configuration

Configure back cover in _index.md:

book:
  # Back cover image
  backcover_image: "back-cover.jpg"
  
  # Back cover text
  backcover_text: "WeChat Official Account: Jimmy Song"
  backcover_link_text: "Read online at jimmysong.io"
  backcover_link_url: "https://jimmysong.io/book/kubernetes-handbook/"
  
  # Back cover colors
  backcover_text_color: "#FFFFFF"
  backcover_link_color: "#1d09d8"

Cover Design Tips

Image Size: Use 16:9 or 4:3 ratio images
Text Contrast: Ensure sufficient contrast between text and background
Font Choice: Tool auto-selects system CJK fonts
Visual Hierarchy: Arrange title, author, and subtitle logically

Advanced Options

Color Themes

Customize document color themes:

book:
  body_color: "#333333"
  heading_color: "#2C3E50"
  link_color: "#3498DB"
  code_color: "#E74C3C"
  quote_color: "#7F8C8D"
  caption_color: "#95A5A6"

Predefined Themes

The tool supports several themes:

Professional Theme: For technical docs
Academic Theme: For academic papers
Warm Theme: For creative books

Key Technical Challenges & Solutions

1. Chinese Font Support

Problem: LaTeX doesn’t support CJK fonts by default, causing garbled text.

Solution: Use xeCJK package and auto-detect system CJK fonts, preferring high-quality fonts.

2. Emoji Rendering

Problem: Traditional LaTeX has poor emoji support, often showing boxes or question marks.

Solution: Use LuaLaTeX engine with emoji package and system emoji fonts for color rendering.

3. Image Processing

Problem: Remote images and some formats aren’t supported by LaTeX.

Solution: Auto-download remote images, convert WebP/SVG to PNG, and implement smart caching.

4. Table Optimization

Problem: Complex tables may overflow or break formatting in PDFs.

Solution: Use tabularx and longtable packages, auto-calculate column widths, and support multi-page tables.

Performance Optimization

Image Caching System

The tool uses file hash-based smart caching to avoid redundant image processing:

def get_cached_image(source_path, cache_dir, target_extension):
    """Check if image is cached"""
    file_hash = hashlib.md5(open(source_path, 'rb').read()).hexdigest()
    cached_path = os.path.join(cache_dir, f"{file_hash}.{target_extension}")
    
    if os.path.exists(cached_path):
        return cached_path
    return None

Error Handling & Retry Mechanism

Robust error handling and retry logic ensure successful exports despite network issues:

def run_with_retry(command, max_retries=3):
    """Run command with retries"""
    for attempt in range(max_retries):
        try:
            result = subprocess.run(command, check=True, capture_output=True)
            return result
        except subprocess.CalledProcessError as e:
            if attempt < max_retries - 1:
                time.sleep(2 ** attempt)  # Exponential backoff
                continue
            raise e

Best Practices

Content Organization

Use Weights: Set appropriate weight in front matter for chapter order
Clear Headings: Use semantic heading levels (H1-H4)
Image Optimization: Use WebP for smaller file sizes

Performance Tips

Clean Cache Regularly: Use --clean-cache to remove expired cache
Incremental Export: For large books, use --generate-summary to preview structure
Choose the Right Engine: Use --engine lualatex for emoji-rich content

Conclusion

PDF Book Exporter combines Hugo’s flexibility, Pandoc’s conversion power, and LaTeX’s professional typesetting to provide a robust PDF export solution for Hugo books. It solves complex rendering scenarios for multilingual content, emoji, math formulas, image processing, and cover design, while offering high customization—ideal for technical books, tutorials, and eBooks.

If you’re looking for a professional PDF export tool for Hugo books, try PDF Book Exporter. Contributions and suggestions are welcome!

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