ironpress

Pure Rust HTML/CSS/Markdown to PDF converter. No browser, no system dependencies.

Other Rust PDF crates shell out to headless Chrome or wkhtmltopdf. ironpress does it natively with a built-in layout engine. No C libraries, no binaries to install, just cargo add ironpress.

Table of Contents

• Quick Start
• API Reference
• Markdown to PDF
• HTML Elements
• CSS Support
• Images
• Tables
• Fonts
• Security
• How It Works
• Roadmap
• License

Quick Start

use ironpress::html_to_pdf;

let pdf_bytes = html_to_pdf("<h1>Hello</h1><p>World</p>").unwrap();
std::fs::write("output.pdf", pdf_bytes).unwrap();

API Reference

One-liner functions

// HTML string to PDF bytes
let pdf = ironpress::html_to_pdf("<h1>Title</h1><p>Content</p>").unwrap();

// Markdown string to PDF bytes
let pdf = ironpress::markdown_to_pdf("# Title\n\nContent").unwrap();

// HTML file to PDF file
ironpress::convert_file("input.html", "output.pdf").unwrap();

// Markdown file to PDF file
ironpress::convert_markdown_file("input.md", "output.pdf").unwrap();

Builder API

use ironpress::{HtmlConverter, PageSize, Margin};

let pdf = HtmlConverter::new()
    .page_size(PageSize::LETTER)        // default: A4
    .margin(Margin::uniform(54.0))      // default: 72pt (1 inch)
    .sanitize(false)                    // default: true
    .convert("<h1>Custom page</h1>")
    .unwrap();

Page sizes

use ironpress::PageSize;

PageSize::A4         // 595.28 x 841.89 pt (default)
PageSize::LETTER     // 612.0 x 792.0 pt
PageSize::LEGAL      // 612.0 x 1008.0 pt
PageSize::new(width_pt, height_pt)  // custom

Margins

use ironpress::Margin;

Margin::default()                    // 72pt on all sides (1 inch)
Margin::uniform(54.0)               // same value on all sides
Margin::new(top, right, bottom, left)  // individual values in pt

Markdown to PDF

Built-in Markdown parser with zero external dependencies.

let pdf = ironpress::markdown_to_pdf(r#"
# Project Title

Some **bold** and *italic* text with `inline code`.

## Features

- Item one
- Item two
- Item three

1. First
2. Second

> A wise quote

---

fn main() { println!("hello"); }

[Link text](https://example.com)
"#).unwrap();

Supported Markdown syntax: headings (# to ######), bold (**), italic (*), bold+italic (***), inline code, fenced code blocks, links, images, unordered lists (-, *, +), ordered lists, blockquotes, and horizontal rules.

HTML Elements

CSS Support

Properties

All properties support shorthand notation. Margin and padding accept 1, 2, 3, or 4 values. Border accepts width style color shorthand.

<style> blocks

<style>
  p { color: navy; font-size: 14pt }
  .highlight { background-color: yellow; font-weight: bold }
  #title { font-size: 24pt }
  h1, h2 { color: darkblue }

  @media print {
    .screen-only { display: none }
  }
</style>

Selectors

Values

Media queries

@media print rules are applied (since PDF is print output). @media screen rules are ignored.

Images

JPEG and PNG images are supported via data URIs and local file paths.

<!-- Data URI -->
<img src="data:image/jpeg;base64,/9j/4AAQ..." width="200" height="150">

<!-- Local file -->
<img src="photo.jpg" width="300" height="200">

Images are embedded directly in the PDF. JPEG uses DCTDecode, PNG uses FlateDecode with PNG predictors. Width and height attributes are converted from px to pt.

Tables

Full table support with sections, spanning, and styling.

<table>
  <thead>
    <tr><th>Name</th><th>Role</th><th>Status</th></tr>
  </thead>
  <tbody>
    <tr>
      <td rowspan="2">Alice</td>
      <td>Engineer</td>
      <td>Active</td>
    </tr>
    <tr>
      <td colspan="2">On project X</td>
    </tr>
    <tr>
      <td>Bob</td>
      <td>Designer</td>
      <td>Active</td>
    </tr>
  </tbody>
</table>

Features: <thead>, <tbody>, <tfoot> sections, colspan and rowspan attributes, bold headers in <th>, cell borders, background colors, and padding.

Fonts

ironpress uses the 14 standard PDF fonts (no font embedding required). CSS font-family values are mapped to the closest match:

Each family includes regular, bold, italic, and bold-italic variants (12 fonts total). Unknown font names default to Helvetica.

Security

HTML is sanitized by default before conversion:

• <script>, <iframe>, <object>, <embed>, <form> tags are stripped
• <style> tags are preserved but dangerous CSS (@import, external url(), expression()) is removed
• Event handlers (onclick, onload, etc.) are removed
• javascript: URLs are neutralized
• Input size (10 MB) and nesting depth (100 levels) are limited

Sanitization can be disabled with .sanitize(false) if you trust the input.

How It Works

Input --> Sanitize --> Parse (html5ever) --> Extract <style> --> Style cascade --> Layout engine --> PDF

1. Sanitize the input HTML to remove dangerous elements
2. Parse HTML into a DOM tree using html5ever, extracting <style> blocks
3. Resolve styles by cascading: tag defaults, then @media print rules, then stylesheet rules, then inline CSS
4. Layout elements with text wrapping, page breaks, tables, lists, images, and the CSS box model
5. Render to PDF 1.4 with text, graphics, link annotations, and embedded images

For Markdown input, a built-in parser converts Markdown to HTML first (no external dependencies).

Roadmap

v0.5 -- New input formats

• Plain text (TXT) to PDF
• CSV to PDF (auto-formatted tables)
• PNG/JPEG to PDF (full-page image conversion)
• XML to PDF

v0.6 -- Vector graphics and e-books

• SVG rendering (paths, shapes, text, basic CSS)
• EPUB to PDF

v0.7 -- Office documents

• DOCX to PDF
• XLSX to PDF (spreadsheet tables)

Planned improvements

• Remote image loading via URL (behind a feature flag)
• TrueType/OpenType font embedding
• CSS float and position properties
• Advanced CSS selectors (descendant, child, attribute)
• Table auto-sizing based on content width
• Hyphenation and text justification

License

MIT