How to Easily Generate PDF from HTML with HexaPDF

Setting Up HexaPDF in Ruby on Rails

Getting started with HexaPDF is straightforward and can be integrated seamlessly within Ruby on Rails applications.

Installing HexaPDF Gem

First, ensure that Ruby (version 2.6 or above, ideally 3.0+) is installed on your system. Then, add HexaPDF to your Rails project by including it in the Gemfile:

# Gemfile
gem 'hexapdf', '~> 1.0.0'

Install the gem by running:

To confirm that HexaPDF is correctly installed, execute the following command:

hexapdf version

Converting HTML to PDF Using HexaPDF

While HexaPDF does not support direct HTML-to-PDF conversion, it provides a powerful Canvas API to help you design PDFs with precision. This approach requires structuring the document layout programmatically, enabling you to create complex documents with fine-tuned control over every element.

Creating a Complete Invoice Layout Using the Canvas API

To demonstrate HexaPDF’s layout capabilities, let’s build a simple invoice PDF layout.

require 'hexapdf'

doc = HexaPDF::Document.new
page = doc.pages.add
canvas = page.canvas
canvas.font('Helvetica', size: 12).fill_color(0, 0, 0)
canvas.text("Invoice", at: [100, 750])
canvas.text("Invoice #: 12345", at: [100, 730])
canvas.text("Date: #{Time.now.strftime("%Y-%m-%d")}", at: [100, 710])
canvas.text("Client: Jane Doe", at: [100, 690])
canvas.text("Amount Due: $500.00", at: [100, 670])
doc.write("invoice.pdf"

In this example, we create a PDF that includes basic text and layout elements. The Canvas API enables custom text placement, color control, and font selection, allowing for a high level of customization. This approach can be scaled to more intricate layouts and formatting styles as needed.

Main Features of HexaPDF

HexaPDF includes a rich array of features, ideal for both simple and complex document creation:

• Pure Ruby Implementation: HexaPDF is written entirely in Ruby, with minimal dependencies, ensuring easy integration and consistent behavior across environments.

• Document Layout Engine: Supports automatic content layout with capabilities such as text wrapping, page breaks, multi-column layouts, and more. The layout system is designed to flow text around images and other elements.

• Comprehensive Canvas API: Direct access to low-level PDF operations enables developers to perform tasks such as drawing paths, shapes, and curves, as well as embedding images and working with TrueType fonts.

• Form Handling and Annotations: Supports PDF forms (AcroForm) and annotations, enabling interactive elements within documents.

• Document Security: Provides encryption, including AES256 for PDF 2.0, and supports digital signatures, making it suitable for handling sensitive information.

• File Optimization: Offers built-in tools for file size reduction without compromising quality, ideal for web applications where file size is a concern.

• Command-line Tool: The hexapdf CLI offers utility commands for tasks such as merging, encrypting, or optimizing PDFs.

These features make HexaPDF a well-rounded PDF solution that balances low-level control with high-level convenience.

How to Use a PDF API to Automate PDF Creation at Scale

For SaaS platforms, automating PDF generation at scale might require offloading the heavy lifting to a PDF API.

It's also an option to integrate with third-party APIs like pdforge you can handle high-volume PDF generation, complex formatting, and post-processing, all from a single backend call.

Here’s an example of how to integrate pdforge in Rails to convert HTML content into a PDF via an API call:

require 'net/http'
require 'json'
require 'uri'

class PdfApiService
  def self.generate_pdf(html_content)
    uri = URI("https://api.pdforge.com/v1/pdf/sync")
    http = Net::HTTP.new(uri.host, uri.port)
    http.use_ssl = true
    request = Net::HTTP::Post.new(uri.path, {
      'Content-Type' => 'application/json',
      'Authorization' => "Bearer your-api-key"
    })
    request.body = {
      templateId: 'your-template',
      data: { html: html_content }
    }.to_json
    response = http.request(request)
    response.body if response.is_a?(Net::HTTPSuccess)
  end
end

This code sends a POST request to the pdforge API, receives the generated PDF, and saves it locally.

Conclusion

HexaPDF is a powerful option for developers who need a lightweight yet feature-rich PDF solution in Ruby. Its design focuses on layout precision, security, and document flexibility, making it ideal for applications requiring advanced PDF handling.

For straightforward HTML-to-PDF conversion with minimal configuration, tools like WickedPDF may still be effective.

However, when handling high PDF volumes or distributing load across services, using an external PDF API such as pdforge provides a robust and scalable solution. Choose the right tool based on your project’s requirements, workload, and infrastructure to achieve the best results.